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Replicating the Fontana-Ingenhousz Eudiometer: Incorporating Historical Experiments in Undergraduate Chemistry Education

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Title: Replicating the Fontana-Ingenhousz Eudiometer: Incorporating Historical Experiments in Undergraduate Chemistry Education
Language: English
Authors: Pieter T. L. Beck (ORCID 0000-0003-4788-4715), Ruby Cornand, Wannes De Turck, Mieke Adriaens
Source: Science & Education. 2025 34(3):1703-1729.
Availability: Springer. Available from: Springer Nature. One New York Plaza, Suite 4600, New York, NY 10004. Tel: 800-777-4643; Tel: 212-460-1500; Fax: 212-460-1700; e-mail: customerservice@springernature.com; Web site: https://link.springer.com/
Peer Reviewed: Y
Page Count: 27
Publication Date: 2025
Document Type: Journal Articles
Reports - Descriptive
Education Level: Higher Education
Postsecondary Education
Descriptors: Undergraduate Students, College Science, Science Education, Chemistry, Measurement Equipment, Laboratory Procedures, Science Experiments, Science History, Creative Thinking, Critical Thinking, Scientific Principles
DOI: 10.1007/s11191-024-00533-z
ISSN: 0926-7220
1573-1901
Abstract: In this article, we discuss the replication of a forgotten chemical instrument in the context of undergraduate chemistry education. Together with students, we have attempted to replicate an eighteenth century "eudiometrical" procedure. Eudiometry was the practice of measuring the "goodness" of the air by looking at the volume reduction of a sample of air when it reacts with specific substances. Our replication of a eudiometer can be seen as an example of what Hasok Chang calls "complementary experiments," a specific type of historical experiments with several benefits for science education. We show how the replication work helped students develop their creative and critical thinking skills, and also facilitated NOS teaching. Moreover, we were able to use the replication work to teach the students contemporary experimental and analytical techniques. Based on our experience, we believe there are benefits to be found in teaching contemporary techniques in the context of complementary experimentation.
Abstractor: As Provided
Entry Date: 2025
Accession Number: EJ1474252
Database: ERIC
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  Value: <anid>AN0185990916;nmo01jun.25;2025Jun19.03:01;v2.2.500</anid> <title id="AN0185990916-1">Replicating the Fontana-Ingenhousz Eudiometer </title> <p>In this article, we discuss the replication of a forgotten chemical instrument in the context of undergraduate chemistry education. Together with students, we have attempted to replicate an eighteenth century "eudiometrical" procedure. Eudiometry was the practice of measuring the "goodness" of the air by looking at the volume reduction of a sample of air when it reacts with specific substances. Our replication of a eudiometer can be seen as an example of what Hasok Chang calls "complementary experiments," a specific type of historical experiments with several benefits for science education. We show how the replication work helped students develop their creative and critical thinking skills, and also facilitated NOS teaching. Moreover, we were able to use the replication work to teach the students contemporary experimental and analytical techniques. Based on our experience, we believe there are benefits to be found in teaching contemporary techniques in the context of complementary experimentation.</p> <p>Keywords: Education Curriculum and Pedagogy Specialist Studies In Education</p> <p>Copyright comment Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.</p> <hd id="AN0185990916-2">Introduction</hd> <p>In science education, the incorporation of historical replications in science teaching has been preached and practiced more and more the last few decades. Exemplary work in this context has been (and is being) performed by (among others) Peter Heering and Elizabeth Cavicchi (see, for example, Heering ([<reflink idref="bib18" id="ref1">18</reflink>]) and Cavicchi ([<reflink idref="bib5" id="ref2">5</reflink>])). Hasok Chang has also tirelessly advocated the incorporation of historical replications in science education and has provided inspiring examples of such work ([<reflink idref="bib6" id="ref3">6</reflink>], [<reflink idref="bib7" id="ref4">7</reflink>], [<reflink idref="bib9" id="ref5">9</reflink>]). Chang sees the replication of historical experiments as part of a more general program of history and philosophy of science (HPS) as "complementary science." That is, the aim is not merely to interpret scientific practice, but to contribute to knowledge generation in the sciences (Chang, [<reflink idref="bib7" id="ref6">7</reflink>], p. 323). Chang agrees with Peter Heering that in this context replicating "forgotten experiments" might even be more instructive than replicating well-known textbook experiments ([<reflink idref="bib7" id="ref7">7</reflink>], p. 323).</p> <p>In this article, we discuss the replication of a forgotten chemical instrument in the context of undergraduate chemistry education. Together with students, we have attempted to replicate an eighteenth century "eudiometrical" procedure. Eudiometry was the eighteenth century practice of measuring the "goodness" of the air by looking at the volume reduction of a sample of air when it reacts with specific kinds of substances. The more volume reduction there occurred, the better the air was considered to be. The first eudiometers used "nitrous air" or nitrogen monoxide (NO), but soon other substances were used such as phosphor, alkaline sulfides, or hydrogen (Grapí, [<reflink idref="bib16" id="ref8">16</reflink>]). Eudiometery was extremely popular in the late eighteenth century, due to the hope that it could be used in the context of public health reforms (Schaffer, [<reflink idref="bib33" id="ref9">33</reflink>]; Golinski, [<reflink idref="bib15" id="ref10">15</reflink>], pp. 105–128; Beretta, [<reflink idref="bib1" id="ref11">1</reflink>]; Boantza, [<reflink idref="bib3" id="ref12">3</reflink>]). When it became clear however that the eudiometer only gave an indication of the oxygen content of a sample of an air sample and that the amount of oxygen in atmospheric air was relatively constant, interest in eudiometry waned (Grapí, [<reflink idref="bib16" id="ref13">16</reflink>]).</p> <p>Together with BA and MA chemistry students, we have attempted to replicate the eudiometric procedure developed by Jan (John) Ingenhousz (1730–1799). Our aims were twofold. On the one hand, we wanted to use the replications to gain a better understanding of the procedures and results published by Ingenhousz. The reason for specifically focusing on Ingenhousz's procedure will be discussed in Section 3.1. Our second aim was to have undergraduate chemistry students actively participating in these replications, not only as a way to learn about the history of chemistry, but also to further develop their experimental and research skills.</p> <p>The article is structured as follows. In Section 2, we provide the necessary historical background to understand the historical replications that we performed. We discuss the development of the "nitrous air test" by Joseph Priestley and then introduce and contextualize the Fontana-Ingenhousz eudiometric procedure developed by Ingenhousz. In Section 3, we give a detailed discussion of the instruments used by Ingenhousz and the specific procedure that he followed for his eudiometric tests. In Section 4, we discuss the replication procedure itself. We first describe the educational context in which these replications were performed. We then provide a discussion of the procedure that we followed and the results that we have obtained. In Section 5, we give a short overview of the relevant literature on the benefits of incorporating replications of historical experiments in science education and compare the points made in the literature with our own findings. Aside from the benefits of incorporating "forgotten experiments" mentioned by Chang, we discuss further benefits that are specific to the work with the eudiometer. It provides a context to teach students specific NOS insights, related to problems with naïve falsificationism and the phenomenon of underdetermination. Finally, we were able to use the replication work as a concrete context to teach the students contemporary experimental and analytical techniques in a way that enhanced their learning.</p> <hd id="AN0185990916-3">Eudiometry: The Historical Background</hd> <p></p> <hd id="AN0185990916-4">Priestley and the "Nitrous Air" Test</hd> <p>As mentioned in the introduction, the practice of "eudiometry" consisted of the assessment of the quality of a sample of air by looking at the way its volume was reduced by reacting with different kinds of substances, such as nitrogen monoxide, hydrogen, and phosphor. The term "eudiometer" was coined by the Italian Marsilio Landriani (1751–1815) (Levere, [<reflink idref="bib25" id="ref14">25</reflink>], p. 112). In 1775, both he and his compatriot Felice Fontana (1730–1805) independently of each other published a tract in which they provided an outline for (a) specific design(s) of a eudiometer (Boantza, [<reflink idref="bib3" id="ref15">3</reflink>], p. 385; Levere, [<reflink idref="bib25" id="ref16">25</reflink>], pp. 111–116).</p> <p>Although the term was only coined later, the development of the first eudiometric procedure should be credited to Joseph Priestley (1733–1804). His 1772 article "Observations on different kinds of air," published in the Royal Society's <emph>Philosophical Transactions</emph>, includes an account of his discovery of a new kind of "air." The gas he had discovered was produced by dissolving metals such as copper and mercury in nitric acid. Because he used nitric acid (<emph>spirit of nitre</emph>) to produce the gas, Priestley decided to give the name "nitrous air" to this new gas (Priestley, [<reflink idref="bib30" id="ref17">30</reflink>], pp. 210–211).[<reflink idref="bib1" id="ref18">1</reflink>] Priestley was especially fascinated by the volume reduction that could be observed when the gas was mixed with atmospheric air. This was done using the experimental set-up depicted in Fig. 1. Glass cylinders were filled with water and in turn put upside down in a tub of water. Gases could then be collected and mixed in these cylinders. The reactions between these gases could also be observed in this way.</p> <p>Graph: Fig. 1 Plate providing an image of the instruments used by Priestley. He makes use of a large tub, filled with water, and a set of cylindrical glass jars (marked with the letter c), which were filled with water and put in the tub. Gases could then be collected and combined in these cylinders. Note that a mouse is depicted as part of the standard equipment (under a jar in front of the trough). Plate from Priestley ([<reflink idref="bib31" id="ref19">31</reflink>])</p> <p>Based on further observations, Priestley concluded that it is mainly the volume of the common air in the mixture that was reduced. By repeating the process over mercury, he also noticed that the volume reduction was less outspoken than when it was performed over water. Water therefore also played a role in the process (Boantza, [<reflink idref="bib2" id="ref20">2</reflink>], pp. 512–516). The most important finding of Priestley was that the volume reduction of the sample of air seemed to correlate to its "fitness for respiration." The latter had been tested independently by putting a mouse in a sealed glass jar filled with the air to be tested. The longer the mouse survived, the better the air was. The longer a sample of air kept a mouse alive, the greater its volume reduction when combined with nitrous air. The amount of reduction also varied significantly, which opened the possibility to develop a measurement scale (Priestley, [<reflink idref="bib30" id="ref21">30</reflink>], 214–215). Since then, Priestley used this "nitrous air test," as he called it, as a standard test for the breathability of the air. It was discussed as such two years later in the first volume of his <emph>Experiments and Observations of Different Kinds of Air</emph> (Priestley, [<reflink idref="bib31" id="ref22">31</reflink>], p. 20).</p> <p>Priestley's understanding of his "nitrous air test" was based on the then current phlogiston theory. This theory goes back to the work of the German chemist Georg Ernst Stahl (1659–1734). Phlogiston is the principle of combustibility. Substances that contain phlogiston are combustible and combustion itself is understood as a process in which phlogiston is released from these combustible substances. Charcoal, for example, is rich in phlogiston and therefore burns easily. Once it is burnt, non-combustible ashes are left because all the phlogiston has been released from the charcoal. The calcination (oxidation) of metals was seen as a process analogous to combustion: metals are rich in phlogiston and when they lose this phlogiston, they turn into calxes (metal oxides). Priestley connected this framework with his pioneering experimental work on "airs," using the concept of phlogiston to understand the nature of different gases and the changes undergone by atmospheric air under the influence of chemical processes. According to Priestley, the phlogiston that was released in combustion was taken up by the ambient air. It was known that a body at some point stops burning when combustion occurs under a closed vessel. Priestley thought that this happened because the air became saturated with phlogiston and could no longer take up phlogiston from the burning body. Combustion could only occur when there was air around capable of taking up the released phlogiston. The uptake of the phlogiston also changed the nature of the air. Not only was it no longer able to support combustion, it also decreased in volume. According to Priestley, this was because it had lost some of its elasticity due to its saturation with phlogiston. To distinguish this air from atmospheric air, Priestley called it "phlogisticated air (N<subs>2</subs>)." This also suggested that air that contained less phlogiston could more readily take it up and should therefore be more apt to support combustion. Priestley discovered that when mercury calx (HgO) was heated in a closed vessel, it turned into mercury. The air in the vessel turned out to support combustion more than common air: when a candle was lit in the vessel, it burned more brightly. According to Priestley, the phlogiston from the air had been removed because the calx had absorbed it when it turned into a metal. He therefore called this air "dephlogisticated air (O<subs>2</subs>)." Priestley also saw a connection between the process of breathing and the process of combustion, and therefore also between the "breathability" of the air and its degree of "phlogistication." He saw breathing as the process by which the body excretes superfluous phlogiston. Therefore, the less phlogiston the air contains, the better it supports breathing (Chang, [<reflink idref="bib8" id="ref23">8</reflink>], pp. 2–5; Conant, [<reflink idref="bib10" id="ref24">10</reflink>], pp. 13–16).</p> <p>Priestley also understood the working of the "nitrous air test" in terms of the phlogiston theory. According to him, "it is the phlogiston that is the test" ([<reflink idref="bib32" id="ref25">32</reflink>], p. 359). When a metal dissolves in an acid, it loses its phlogiston. This phlogiston combines with the nitrous acid to form "nitrous air." Because it is saturated with phlogiston, the nitrous air does not have the typical color of "fumes of spirit of nitre" (Priestley, [<reflink idref="bib32" id="ref26">32</reflink>], p. 360). Once it loses its phlogiston to the air however, it regains this typical red color. The more "dephlogisticated" a sample of air is, the more it is able to take over phlogiston from the nitrous air, the more red fumes are produced (Priestley, [<reflink idref="bib32" id="ref27">32</reflink>], pp. 359–360). Because the air takes up the phlogiston from the "nitrous air," it becomes more phlogisticated and is reduced in volume (Boantza, [<reflink idref="bib2" id="ref28">2</reflink>], pp. 512–516).</p> <p>The contemporary explanation for the working of the nitrous air eudiometer is somewhat different. The main principle behind it rests on the fact that NO combines with oxygen (O<subs>2</subs>) to form NO<subs>2</subs>:</p> <p>NO is not readily soluble in water, while NO<subs>2</subs> is. When the test is performed over water, the NO<subs>2</subs> produced by the reaction between NO and O<subs>2</subs> will thus dissolve, lowering the volume of gas and making the water level in the jar rise. The more O<subs>2</subs> in the sample of air tested, the more NO<subs>2</subs> will be produced and the more the water level will rise. The"nitrous air" eudiometers that were developed after Priestley were based on the same basic principle. Later methods differed with regard to the amount of nitrous air used, the manner of combining the nitrous air and the air sample, the design and manipulation of the test tube, the timing, etc. (Grapí, [<reflink idref="bib16" id="ref29">16</reflink>], p. 12; Boantza, [<reflink idref="bib3" id="ref30">3</reflink>], p. 383). One such method is that of Jan Ingenhousz, to which we will now turn.</p> <hd id="AN0185990916-5">The Fontana-Ingenhousz Eudiometer</hd> <p></p> <hd id="AN0185990916-6">Introduction</hd> <p>The Dutch-born British Jan (John) Ingenhousz (1730–1799) is best known for his work on the process that would later be called photosynthesis. He showed that plants produced oxygen ("dephlogisticated air") in the sun and carbon dioxide ("fixed air") in the dark. The eudiometer played an important role in these investigations as a means to test the air produced by plants. In his work, Ingenhousz presented a revised version of the eudiometer designed by Felice Fontana (Magiels, [<reflink idref="bib26" id="ref31">26</reflink>]). Although the Fontana-Ingenhousz eudiometric procedure was criticized by Priestley and his followers (Boantza, [<reflink idref="bib3" id="ref32">3</reflink>]; Grapí, [<reflink idref="bib16" id="ref33">16</reflink>], pp. 79–88), it was one of the most important and popular "nitrous air" eudiometers, and according to Grapí, it was "reasonably standardized" ([<reflink idref="bib16" id="ref34">16</reflink>], p. 118). In an article describing a newly developed eudiometer, Henry Cavendish mentions the Fontana eudiometer as "the most accurate of any hitherto published" (Cavendish, [<reflink idref="bib4" id="ref35">4</reflink>], p. 3). Ingenhousz was extremely preoccupied with standardizing his procedure, so that even non-skilled operators could perform the measurement and obtain reliable results. For this, he gave an extremely detailed account of the procedure to be followed and listed all possible sources of error (Boantza, [<reflink idref="bib3" id="ref36">3</reflink>], pp. 389–391; Grapí, [<reflink idref="bib16" id="ref37">16</reflink>], pp. 108–113). Taking into account these remarks on the accuracy and consistency of the Fontana-Ingenhousz eudiometer and the availability of detailed accounts of the procedure in the primary literature, we decided that the Fontana-Ingenhousz eudiometer was a perfect candidate for a replication. Before discussing our replication process, we will give an outline of the description of the apparatus and the procedure as found in the primary sources.</p> <hd id="AN0185990916-7">Description of the Apparatus</hd> <p>The apparatus used by Ingenhousz consisted of several parts. The two main parts are the so-called great measure (CCCC on Fig. 2) and small measure (Fig. II on Fig. 2), i.e., two cylindrical glass cylinders which are closed off at one end. The "great measure" is a glass cylindrical tube of about 487.3–541.4 mm long.[<reflink idref="bib2" id="ref38">2</reflink>] Its diameter should be about 13.5 mm, "or not much less, though it may be larger" (Ingenhousz, [<reflink idref="bib19" id="ref39">19</reflink>], p. 153). In a later article on the construction and use of the eudiometer, Ingenhousz states that he thinks it is better that the diameter should not be bigger than 13.5 mm. If the diameter is wider, the column of air rises up in the cylinder too fast (Ingenhousz, [<reflink idref="bib22" id="ref40">22</reflink>], p. 347). We will see why this would pose a problem when we discuss the method of using the apparatus.</p> <p>Graph: Fig. 2 Depiction of Ingenhousz's eudiometer. Fig. I shows a brass cylinder (AAAA) filled with water, in which the "great measure" or great glass cylinder (CCCC) is suspended from two brass rings. The brass tube is represented in a transparent manner so that one can see the presence of the glass cylinder. Above the brass cylinder, a brass scale (BB) is present, subdivided in 100 parts. The scale slider is also shown in Fig. IV. A magnifier (D) allows accurate readings of the scale. Figs. II and III represent the "small measure" or small glass tube which is fixed in a brass socket. Image from (Ingenhousz, [<reflink idref="bib19" id="ref41">19</reflink>])</p> <p>The great measure is marked with division marks, 81.2 mm apart from each other (the reason for this will soon become clear). Each section is again subdivided in 100 equal parts. This is not done by adding engravings to the glass, but by using an engraved brass slider or cylinder, open at both sides, which can be moved along the length of the glass cylinder (Fig. IV or BB in Fig. 2). The use of the slider will be discussed in the section below. The glass on the inside of the cylinder should be abraded to avoid waterdrops adhering to the insides. The presence of waterdrops would invalidate the volume measurement of the column of water (Ingenhousz, [<reflink idref="bib19" id="ref42">19</reflink>], pp. 153–154).</p> <p>The "small measure" should have the same diameter as the "great measure" and has a length of 81.2 mm (thus corresponding to the length of the divisions made on the "great measure"). The inside should also be abraded. This small glass cylinder is fitted on a brass socket. When the cylinder is full of air, it can be closed by means of a slider, ensuring that an exact and constant measure of air can be used for the test (Ingenhousz, [<reflink idref="bib19" id="ref43">19</reflink>], pp. 154–155).</p> <hd id="AN0185990916-8">The Hybrid Priestley-Fontana Method (HPF)</hd> <p>In his <emph>Experiments upon Vegetables</emph> (1779), Ingenhousz describes two eudiometric methods: the one of Fontana, and an abridged version that he himself had developed to analyze common air. As we followed the latter procedure in our own replications, we will only discuss this method. The abridged procedure could be performed in one or two minutes and the results were, according to Ingenhousz, accurate ([<reflink idref="bib19" id="ref44">19</reflink>], p. 278). He clarifies that the abridged method is in fact a combination of elements of the method developed by Priestley with elements of Fontana's method. We will therefore henceforth refer to this method as the Hybrid Priestley-Fontana Method (HPF). This method consists in combining one measure of common air with one measure of nitrous air. First, a measure of common air is put in the glass tube with the small measure. Then, a measure of nitrous air is added. Ingenhousz closes the cylinder with his thumb and starts shaking it at the precise moment the two airs come into contact. He adds that he shakes the cylinder under water for exactly thirty seconds.[<reflink idref="bib3" id="ref45">3</reflink>] He then puts the glass cylinder in a vertical position in the copper cylinder (AAA in Fig. 3) and waits for a minute, meanwhile pouring water over the glass cylinder, to bring it back to the temperature of the water after it has been handled by the warm hands of the operator. He then puts the brass scale over the glass cylinder and makes sure that the zero mark of the scale corresponds with the point where the air and the water meet (Ingenhousz, [<reflink idref="bib19" id="ref46">19</reflink>], pp. 156, 279–281). The scale works as a vernier scale, allowing one to read the results in terms of measures and hundredths of measures.</p> <p>Graph: Fig. 3 Set-up used by Ingenhousz. Flask a (right hand side) is filled with copper and nitric acid to synthesize "nitrous air." The flask is positioned next to a water basin and is connected with a glass jar in such a way that the glass tube remains under water with the open end pointing upwards into an inverted jar b, full of water. Jar b rests on a shelf and collects the nitrous air. The center of the figure shows the great measure or great glass cylinder, d, with on top the brass scale. The great measure is filled with water and is being held by one hand at the bottom of the cylinder and is being positioned over hole e in the shelf. The small measure, having been filled with air and having been closed with a slider, is held with the other hand, and positioned under the hole e after which the slider is being opened and the air rushes out into the great measure. The cylinder, c, on the left-hand side is the copper or brass cylinder in which the great measure is carefully placed (without emerging from the water by tilting cylinder c). Ingenhousz does not explain how he moves the nitrous air from jar b to the small measure. Based on other passages and other texts from the period, we suspect that he either tilted the jar under water and used a funnel to direct the nitrous air into the small measure. Or he immediately filled the small measure by means of the tube connected to flask a. Detail from second plate in Ingenhousz ([<reflink idref="bib21" id="ref47">21</reflink>])</p> <p>In a later, expanded French edition of his work, Ingenhousz mentions that the average result of this procedure, when testing atmospheric air, is about 1 measure (Ingenhousz, [<reflink idref="bib23" id="ref48">23</reflink>], p. 204). This average result was also mentioned by others, such as Cavendish ([<reflink idref="bib4" id="ref49">4</reflink>], p. 3). The lowest result published by Ingenhousz for a test of atmospheric air by means of this method is 0.945 measures ([<reflink idref="bib20" id="ref50">20</reflink>], p. 367).</p> <hd id="AN0185990916-9">The Replication</hd> <p></p> <hd id="AN0185990916-10">Context of the Replications</hd> <p>The first series of replications were performed with MA students in April and May 2022.[<reflink idref="bib4" id="ref51">4</reflink>] The students were enrolled in an optional course "History of Chemistry." They had been given a small introduction on the idea behind the replication and were offered the opportunity to participate as an alternative to the mandatory paper they had to write for the course. Eleven students volunteered.[<reflink idref="bib5" id="ref52">5</reflink>] Because it was a minor course with a small amount of contact hours, there was not a lot of time to work in the lab. The main focus of the experimental work was to develop a proof of concept. We developed a procedure for producing NO (discussed in Section 4.2) and performed a first series of replication experiments, using gas syringes and glasswork available at the lab. The method followed is discussed at the beginning of Section 4.3. In February and March 2023, we performed a more elaborate series of experiments with two third-year BA students (listed as co-author). At Ghent University, in the final year of their bachelor's studies, students are expected to perform a short in-house internship and participate in the ongoing research performed at the faculty. Students can choose the research they wish to participate in. Two students chose to work on the replication. They were explicitly informed that the project was intended to be an open-ended investigation during which they could and should provide input. Because of their input, they are mentioned as co-authors. Dr. Beck worked in the lab alongside the students and continued his research on the historical sources. In Section 5, we will provide further information on the experience of the students and the role of the supervisors.</p> <p>In the replication process, decisions had to be made regarding historical accuracy. How historically correct did we want our replication of the Ingenhousz-Fontana eudiometer to be? In our work, we used the following methodology, described by Fors, Principe, and Sibum:In many cases it is more appropriate to undertake a reproduction by first abstracting what are considered to be (at least in a first approximation) the essential features of the historical process. [...] Original features which the historian considers to be irrelevant to the final outcome are initially ignored in order to simplify the reproduction. For example, one might use vessels made of modern Pyrex glass instead of early modern soft glass [...] A stripped-down or streamlined version of the process can then be carried out more easily than if a higher degree of "fidelity" were demanded from the outset. If the outcome is not successful, then previously omitted variables can be returned one at a time, and the results reassessed. Clearly this is a laborious and time-consuming process where many failures precede the first (and often limited) success, but it does allow the historian to identify the key variables, often uncovering and identifying unexpected crucial factors in the process. The sequential addition of complexities is one of things that turns the experiment into a learning experience, and sometimes yields the most important results. (Fors et al., [<reflink idref="bib14" id="ref53">14</reflink>], p. 94).</p> <p>We started with a very "anachronistic" and streamlined version of the procedure (discussed in Section 4.3) and gradually introduced variations which brought the process closer to the historical original (discussed in Sections 4.3 and 4.4). Our research was guided by the fact that the results of our first tests deviated significantly from the results mentioned by Ingenhousz. We got an average result of 1.4 measures. This result is consistent with the main reaction that is often mentioned in the secondary literature when the nitrous air eudiometer is discussed (see, e.g., Conant, [<reflink idref="bib10" id="ref54">10</reflink>], pp. 18–19):</p> <p> <ephtml> <math display="block" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mn>2</mn><mspace width="0.277778em" /><mi mathvariant="normal">NO</mi><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">g</mi></mfenced><mo>+</mo><msub><mi mathvariant="normal">O</mi><mn>2</mn></msub><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">g</mi></mfenced><mo stretchy="false">⇌</mo><mn>2</mn><mspace width="0.277778em" /><msub><mi mathvariant="normal">NO</mi><mn>2</mn></msub><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">g</mi></mfenced></mrow></math> </ephtml> </p> <p>Graph</p> <p>Assuming that atmospheric air contains about 21% oxygen, this reaction suggests a result of 1.37 measures.[<reflink idref="bib6" id="ref55">6</reflink>] One measure of atmospheric air contains 0.21 measures of oxygen. One volume of oxygen combines with two volumes of NO to form NO<subs>2</subs>, which dissolves in the water. The 0.21 measures of oxygen from the measure of atmospheric air thus combine with 0.42 measures of NO from the measure of "nitrous air." This leaves 1.37 measures to remain in the glass cylinder. However, Ingenhousz and his contemporaries consistently mentioned an average result of 1.0 measure. While searching the literature for an answer, we found a more detailed account of the reaction of NO with oxygen. Apparently, there are also some side reactions at play. In the article on their replications of Dalton's nitric oxide experiments, Usselman et al. ([<reflink idref="bib36" id="ref56">36</reflink>], p. 107) give the following reactions for the reaction of NO with oxygen at 298 K:</p> <olist> <item> <ephtml> <math display="block" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mtable><mtr><mtd><mrow><mn>2</mn><mspace width="0.277778em" /><mi mathvariant="normal">NO</mi><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">g</mi></mfenced><mo>+</mo><msub><mi mathvariant="normal">O</mi><mn>2</mn></msub><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">g</mi></mfenced><mo stretchy="false">⇌</mo><mn>2</mn><mspace width="0.277778em" /><msub><mi mathvariant="normal">NO</mi><mn>2</mn></msub><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">g</mi></mfenced></mrow></mtd><mtd><mrow><msub><mi>K</mi><mn>1</mn></msub><mo>=</mo><mn>1.5</mn><mo>×</mo><msup><mn>10</mn><mn>6</mn></msup><mspace width="0.277778em" /><msup><mrow><mi mathvariant="normal">atm</mi></mrow><mrow><mo>-</mo><mn>1</mn></mrow></msup></mrow></mtd></mtr></mtable></mrow></math> </ephtml> </item> </olist> <p>Graph</p> <p>2 <ephtml> <math display="block" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mtable><mtr><mtd><mrow><mn>2</mn><mspace width="0.277778em" /><msub><mi mathvariant="normal">NO</mi><mn>2</mn></msub><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">g</mi></mfenced><mo stretchy="false">⇌</mo><msub><mi mathvariant="normal">N</mi><mn>2</mn></msub><msub><mi mathvariant="normal">O</mi><mn>4</mn></msub><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">g</mi></mfenced></mrow></mtd><mtd><mrow><msub><mi>K</mi><mn>2</mn></msub><mo>=</mo><mn>6.57</mn><mspace width="0.277778em" /><msup><mrow><mi mathvariant="normal">atm</mi></mrow><mrow><mo>-</mo><mn>1</mn></mrow></msup></mrow></mtd></mtr></mtable></mrow></math> </ephtml></p> <p>Graph</p> <p>3 <ephtml> <math display="block" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mtable><mtr><mtd><mrow><mi mathvariant="normal">NO</mi><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">g</mi></mfenced><mo>+</mo><msub><mi mathvariant="normal">NO</mi><mn>2</mn></msub><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">g</mi></mfenced><mo stretchy="false">⇌</mo><msub><mi mathvariant="normal">N</mi><mn>2</mn></msub><msub><mi mathvariant="normal">O</mi><mn>3</mn></msub><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">g</mi></mfenced></mrow></mtd><mtd><mrow><msub><mi>K</mi><mn>3</mn></msub><mo>=</mo><mn>0.52</mn><mspace width="0.277778em" /><msup><mrow><mi mathvariant="normal">atm</mi></mrow><mrow><mo>-</mo><mn>1</mn></mrow></msup></mrow></mtd></mtr></mtable></mrow></math> </ephtml></p> <p>Graph</p> <p>4 <ephtml> <math display="block" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi mathvariant="normal">N</mi><mn>2</mn></msub><msub><mi mathvariant="normal">O</mi><mn>4</mn></msub><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">g</mi></mfenced><mo>+</mo><msub><mi mathvariant="normal">H</mi><mn>2</mn></msub><mi mathvariant="normal">O</mi><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">I</mi></mfenced><mo stretchy="false">→</mo><msub><mi mathvariant="normal">HNO</mi><mn>3</mn></msub><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">aq</mi></mfenced><mo>+</mo><msub><mi mathvariant="normal">HNO</mi><mn>2</mn></msub><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">aq</mi></mfenced></mrow></math> </ephtml></p> <p>Graph</p> <p>5 <ephtml> <math display="block" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi mathvariant="normal">N</mi><mn>2</mn></msub><msub><mi mathvariant="normal">O</mi><mn>3</mn></msub><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">g</mi></mfenced><mo>+</mo><msub><mi mathvariant="normal">H</mi><mn>2</mn></msub><mi mathvariant="normal">O</mi><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">I</mi></mfenced><mo stretchy="false">→</mo><mn>2</mn><mspace width="0.277778em" /><msub><mi mathvariant="normal">HNO</mi><mn>2</mn></msub><mspace width="0.277778em" /><mfenced close=")" open="("><mi mathvariant="normal">aq</mi></mfenced></mrow></math> </ephtml></p> <p>Graph</p> <p>As we have discussed above, if we only take into account reaction (<reflink idref="bib1" id="ref57">1</reflink>), we expect 1.37 volumes of gases remaining in the cylinder after the reaction. This remaining sample consists of 0.58 volume of NO and 0.79 volume of N<subs>2</subs>. Reaction (<reflink idref="bib3" id="ref58">3</reflink>) shows that even when all the O<subs>2</subs> has been reacted away, there is still the possibility of the volume of NO being reduced further through a reaction with the NO<subs>2</subs> that had been formed by reaction (<reflink idref="bib1" id="ref59">1</reflink>). If we take this into account, the least possible amount of gases remaining in the cylinder after combining one volume of NO and one volume of atmospheric air over water is 0.95 volumes. In this case, all the NO<subs>2</subs> formed in reaction (<reflink idref="bib1" id="ref60">1</reflink>) would have to combine with the remaining NO in the cylinder, in the way described by reaction (<reflink idref="bib3" id="ref61">3</reflink>). This maximum limit of volume reduction seemed consistent with fact that Ingenhousz's results did not go below 0.945. It thus seemed to be that Ingenhousz's procedure favored the occurrence of side reaction (<reflink idref="bib3" id="ref62">3</reflink>). We found no immediate explanation why this is the case, but decided to pursue the matter experimentally and see whether we could obtain a result of around one measure remaining volume by approximating Ingenhousz's method. The details of this process will be discussed in the following sections.</p> <hd id="AN0185990916-11">Producing NO</hd> <p>As mentioned above, "nitrous air" was produced by dissolving certain metals in nitric acid. Ingenhousz preferred to use copper wire and provided the following description of his procedure:I coil strong copper wire, neeled [i.e. annealed] so as to be flexible, up in small curls, and fill the phial with them. Thus the nitrous acid, diluted with five or six times the quantity poured in [...] yields in a short time a large quantity of nitrous air very constant in quality. (Ingenhousz, [<reflink idref="bib19" id="ref63">19</reflink>], pp. 170-171)</p> <p>In our replication of Ingenhousz's procedure for generating NO (see Fig. 3), we used the set-up depicted in Fig. 4. Despite the simplicity of the set-up, complexities already arose during this part of the replication. During our first trials, we observed that the "nitrous air" that we produced did not seem to react with samples of atmospheric air. After going over and checking the different components of the set-up, we realized that we had put the end of the plastic tube under the glass jar too soon and had thus also collected the atmospheric nitrogen still present in the flask and tube. The question of course is how long one should wait before one starts to collect the gas coming out of the tube. In our replications, we assessed the proper moment visually by looking at the color change inside the flask and the tube. We waited until the flask and the tube had been filled completely with the orange-brown NO<subs>2</subs> and took this as a sign that the nitrogen and trace gases had been flushed out.</p> <p>Graph: Fig. 4 Replication of Ingenhousz's procedure for generating NO. Coiled-up copper wire is put in a Büchner flask. Water and nitric acid are added. The flask is closed off with a stopper and sealed using parafilm®</p> <p>Another practical issue we encountered was that the reaction between the copper and nitric acid had to produce enough pressure in order to push the gases out of the flask and into the tube. In the same citation, Ingenhousz says that he used nitric acid diluted with five or six times the amount of water. Unfortunately, we do not know how concentrated the nitric acid used by Ingenhousz would have been. When using water and nitric acid (65% concentration) in the aforementioned proportion, we only got a very slow reaction and not enough pressure. In the French edition, Ingenhousz leaves it at the discretion of the reader to decide how strong the nitric acid should be. He first says that the nitric acid should be of a medium strength (<emph>d'une force mediocre</emph>), or as strong as the <emph>eau-forte</emph> that is commonly sold in stores. Nitric acid which is too strong gives a too violent reaction, according to him, whereas acid which is too weak does not produce enough gas in a short amount of time. He concludes that "a little experience will be enough to soon see the quality of <emph>eau-forte</emph> one needs to obtain one's goal" (Ingenhousz, [<reflink idref="bib23" id="ref64">23</reflink>], p. 216). After some trials, we opted for using a ratio of equal amounts of nitric acid and water. If the reaction was not strong enough, we added some more acid. Since Ingenhousz gave no specifications as to the amount of copper that should be used, we did not weigh the copper or used a specified amount of copper. After a while, we were able to intuitively assess how much copper and acid we should use to obtain the desired amount of NO.</p> <hd id="AN0185990916-12">Replication of the Eudiometric Procedure Using Modern Glasswork</hd> <p>For the preliminary replications using modern glasswork, we worked with graduated cylinders of different sizes (see Figs. 5, 6). These were filled with water and put upside down in water, as shown in Fig. 5. Unless mentioned otherwise, we used tap water at room temperature. The temperature of the water ranged between 15 and 17 °C. To mix the atmospheric air with the NO, we first used gas syringes as shown in Fig. 5. The use of syringes allowed us to introduce exact volumes of the gases into the cylinders. It also provided a safe way of taking a sample of NO from under the glass jar and moving it to the cylinder, without the risk of leaks. Following the procedure outlined by Ingenhousz, we first introduced one measure of atmospheric air and then added an equal measure of NO. We then waited exactly one minute before reading the result. For the first series of experiments, we deviated from Ingenhousz's method by not shaking the cylinder, as to have a baseline which would allow us to assess the effect of shaking on the results.</p> <p>Graph: Fig. 5 Inverted graduated cylinder. A gas syringe is used to transfer the gases into the cylinder</p> <p>Graph: Fig. 6 The graduated cylinders used in the experiments. Left, one sees the small bottles used to insert the NO, analogous to Ingenhousz's use of a "small measure." A plastic card (seen lying on the second bottle) was used to close the bottle</p> <p>In the experiments just mentioned, we used a syringe to add the NO to the atmospheric air (Table 1). The NO was added slowly into the cylinder, in the form of small gas bubbles. This deviates from Ingenhousz's method, in which a "measure" of nitrous air was added at once. In our first experiments, we also did not shake the cylinder. Ingenhousz repeatedly emphasizes the importance of shaking the glass cylinder and puts even more emphasis on the timing of the shaking. This should be done at the moment the gases meet, or preferably even sooner (Ingenhousz, [<reflink idref="bib19" id="ref65">19</reflink>], p. 156; [<reflink idref="bib23" id="ref66">23</reflink>], p. 326).</p> <p>Table 1 Results of first series of experiments in which the NO was added to a sample of air in an inverted graduated cylinder by slowly adding it in bubbles. The cylinders were not shaken. All measurements were performed three times for each type of cylinder. In each case the results were identical</p> <p> <ephtml> <table frame="hsides" rules="groups"><thead><tr><th align="left"><p>Volume of cylinder (mL)</p></th><th align="left"><p>Volume of measure (mL)</p></th><th align="left"><p>Result (mL)</p></th><th align="left"><p>Result in measures</p></th></tr></thead><tbody><tr><td align="left"><p>10.0</p></td><td align="left"><p>4.0</p></td><td align="left"><p>5.8</p></td><td char="." align="char"><p>1.5</p></td></tr><tr><td align="left"><p>10.0</p></td><td align="left"><p>5.0</p></td><td align="left"><p>7.4</p></td><td char="." align="char"><p>1.5</p></td></tr><tr><td align="left"><p>25.0</p></td><td align="left"><p>5.0</p></td><td align="left"><p>6.5</p></td><td char="." align="char"><p>1.3</p></td></tr><tr><td align="left"><p>25.0</p></td><td align="left"><p>6.0</p></td><td align="left"><p>8.0</p></td><td char="." align="char"><p>1.3</p></td></tr><tr><td align="left"><p>100</p></td><td align="left"><p>10</p></td><td align="left"><p>13</p></td><td char="." align="char"><p>1.3</p></td></tr><tr><td align="left"><p>100</p></td><td align="left"><p>20</p></td><td align="left"><p>26</p></td><td char="." align="char"><p>1.3</p></td></tr><tr><td align="left" /><td align="left" /><td align="left"><p><bold>Average:</bold></p></td><td char="." align="char"><p>1.4</p></td></tr></tbody></table> </ephtml> </p> <p>In the description of the HPF method, Ingenhousz states that he "begin[s] to shake forcibly this tube in the water trough exactly 30 s (beginning the motion precisely at the moment the two airs come into contact)" ([<reflink idref="bib19" id="ref67">19</reflink>], p. 280). In a later article, Ingenhousz would state that experience has shown him that twelve to fifteen seconds of shaking suffice ([<reflink idref="bib22" id="ref68">22</reflink>], p. 355). In this same article, Ingenhousz explicitly links the recommended dimension of the glass cylinder with the necessity of precisely timing the moment at which one starts shaking the cylinder. If the diameter of the cylinder is larger than recommended, the nitrous air goes up too fast and one cannot possibly start shaking the cylinder in time ([<reflink idref="bib22" id="ref69">22</reflink>], p. 347).</p> <p>We used the following procedure using modern glassware in order to approximate Ingenhousz's method as closely as possible. As in the previous experiments, a graduated cylinder was filled with water and put upside down in a tub of water. Again, the sample of common air was introduced into the cylinder by using a syringe. No syringe was used however to add the NO. Instead, we looked for a way to mimic Ingenhousz's "small measure." To do this, we used two small glass bottles (left in Fig. 6). These were submerged under water until they were completely filled with water and then turned upside down with their opening facing downwards. We then used a syringe to put a specific amount of NO in the small bottle. As an analogue to the slider Ingenhousz used to close his "small measure," we used a small card of hard plastic (seen lying on one of the small bottles in Fig. 6).</p> <p>Following Ingenhousz's instructions, we tried to start shaking the cylinder as soon as possible after introducing the NO with the small bottle. Given the dimensions of our cylinder, the NO rose quite rapidly. It was therefore necessary to perform the manipulations with two persons: one person introducing the NO, and the other person putting the stopper on the cylinder and shaking it afterwards.</p> <p>In order to make sure that the differences in the results were not due to the use of the bottle to move the NO into the cylinder, we first made a series of measurements without shaking the cylinder (Table 2). In the case of the 100-mL cylinder, the results were identical; in the case of the 25-mL cylinder, the results were even a bit higher.</p> <p>Table 2 Results obtained by adding the NO all at once with a bottle, instead of using gas syringes. The cylinders were not shaken. All measurements were performed three times for each type of cylinder. In each case the results were identical</p> <p> <ephtml> <table frame="hsides" rules="groups"><thead><tr><th align="left"><p>Volume of cylinder (mL)</p></th><th align="left"><p>Volume of measure (mL)</p></th><th align="left"><p>Result (mL)</p></th><th align="left"><p>Result in measures</p></th></tr></thead><tbody><tr><td align="left"><p>25.0</p></td><td align="left"><p>6.0</p></td><td align="left"><p>8.5</p></td><td char="." align="char"><p>1.4</p></td></tr><tr><td align="left"><p>100</p></td><td align="left"><p>10</p></td><td align="left"><p>13</p></td><td char="." align="char"><p>1.3</p></td></tr><tr><td align="left" /><td align="left" /><td align="left"><p><bold>Average:</bold></p></td><td char="." align="char"><p>1.4</p></td></tr></tbody></table> </ephtml> </p> <p>The following results were obtained when the cylinder was shaken after inserting the NO (Table 3).</p> <p>Table 3 Results obtained by adding the NO all at once with a bottle and shaking the cylinders immediately afterwards. All measurements were performed three times for each type of cylinder. In each case, the results were identical, with the exception of the measurements with the 100 mL cylinder, which twice gave a result of 22.5 mL and one time gave a result of 25 mL</p> <p> <ephtml> <table frame="hsides" rules="groups"><thead><tr><th align="left"><p>Volume of cylinder (mL)</p></th><th align="left"><p>Volume of measure (mL)</p></th><th align="left"><p>Result (mL)</p></th><th align="left"><p>Result in measures</p></th></tr></thead><tbody><tr><td align="left"><p>25.0</p></td><td align="left"><p>6.0</p></td><td align="left"><p>7.0</p></td><td char="." align="char"><p>1.2</p></td></tr><tr><td align="left"><p>100</p></td><td align="left"><p>10</p></td><td align="left"><p>11</p></td><td char="." align="char"><p>1.1</p></td></tr><tr><td align="left"><p>100</p></td><td align="left"><p>20</p></td><td align="left"><p>22.5</p></td><td char="." align="char"><p>1.1</p></td></tr><tr><td align="left"><p>100</p></td><td align="left"><p>20</p></td><td align="left"><p>25</p></td><td char="." align="char"><p>1.3</p></td></tr><tr><td align="left" /><td align="left" /><td align="left"><p><bold>Average:</bold></p></td><td char="." align="char"><p>1.2</p></td></tr></tbody></table> </ephtml> </p> <p>The resulting volumes were indeed lower and started to approach the result of one measure. However, performing these measurements was not straightforward. A lot of measurements failed, either due to the NO escaping out of the bottle or due to waiting too long before shaking the cylinder. Performing the measurement with two persons required a delicate coordination. It was only after a long series of repetitions that we were able to obtain consistent results. Given these operational difficulties and the fact that we were still not able to reproduce a result of 1.0 measure, we decided to order custom made glassware that resembled Ingenhousz's instrument more closely.</p> <hd id="AN0185990916-13">Replications Using Reconstruction of Ingenhousz-Fontana Eudiometer</hd> <p>To avoid confusion, in what follows we will remain using the term "small measure," but will use the term "cylinder" to refer to our "great measure" in order to differentiate it from Ingenhousz's "great measure" when it is mentioned.</p> <p>To procure custom-made glasswork, we contacted Thibault Martre and Tim Gijs from the Central Technical-Scientific Workshop at Ghent University. At this point, we had to make some decisions on how precise and historically exact we wanted our replication to be. From our reading of the primary sources and the experiments that we had performed, it had become clear that the dimensions of the glass cylinder and the timing of the shaking were the most important. We therefore decided to focus on having a cylinder and small measure with the proper dimensions. For the small measure, we also wanted to have a slider mechanism similar to the one used by Ingenhousz, in order for the manipulations to be made with more ease and the timing to be more optimal. We would have liked to have a cylinder with a diameter of 13.5 mm, corresponding to the diameter suggested by Ingenhousz. In the workplace however, only glass cylinders with standard diameters were present. We therefore opted for the cylinders in stock, but ordered two cylinders with a different diameter. One was a bit smaller, having a diameter of 10.3 mm, the other a bit wider, having a diameter of 15.0 mm. Both cylinders were 500.0 mm long; the small measures were 100.0 mm long. The mouth of both cylinders was made a bit wider, as depicted on the illustration of the instrument provided by Ingenhousz (see CCCC in Fig. 2); this is to ensure that no gas escapes when the content of the small measure is put in the cylinder. The glass cylinder and the small measure were made of borosilicate glass. A polyoxymethylene (POM) socket was made in which the small measure glass could be fitted at one side and the cylinder at the other. PTFE (Polytetrafluoroethylene) was used for the slider, which closed of the content of the small measure glass in a similar way as Ingenhousz's brass slider (Figs. 7, 8).</p> <p>Graph: Fig. 7 (Left) Replica of the Ingenhousz-Fontana eudiometer. Two pairs of glass cylinders, analogous to Ingenhousz's "small measure" and "great measure." The "small measure" is disassembled: to the left is the slider which can be used to open and close the small measure when it is fitted in the socket. The large cylinders are 500.0 mm long, the small cylinders 100.0 mm. The first pair of cylinders has a diameter of 10.3 mm, the second a diameter of 15.0 mm</p> <p>Graph: Fig. 8 3D drawing of the assembled replication. The glass cylinders are fitted in the socket; the PTFE slider can be used to open and close the small cylinder to trap and release the gases. Image produced by Thibault Martre from the Central Technical-Scientific Workshop of Ghent University</p> <p>The glasswork was not graduated, so it was necessary to calibrate the instrument ourselves. This was done in the following way. Both the small measure and cylinder were first rinsed with a 2% solution of RBS 25 detergent. The great measure was then filled with water, positioned with its opening in a basin of water and fixed with a clamp. A level was used to ensure that the cylinder was exactly positioned perpendicularly. One measure of atmospheric air was inserted, using the small measure. A first (preliminary) mark was made on the cylinder corresponding to the point in the cylinder where the gas and the water met. This was done by rolling down a small rubber band. A second measure of atmospheric air was added in the same way. A second mark was made on the cylinder, again by using a rubber band. The place of this rubber band was also marked with a permanent marker. The distance between the two upper rubber bands was then measured. This distance was taken as the actual distance that there should be between marks on the cylinder representing measures. Before moving the cylinder out of the water, a third rubber band was used to mark the place where the cylinder entered the water, to ensure that the mouth of the cylinder was always at the same depth in the water when performing the calibration and the measurements (Fig. 9). This was necessary because the depth of the mouth had an influence on the volume occupied by the gas. When the mouth was moved deeper under water, the upward pressure of the water compressed the gas. This had a small, but non-negligible result on the volume reading.[<reflink idref="bib7" id="ref70">7</reflink>] During the calibrations, it became clear that the smallest cylinder, with a diameter of 10.3 mm, was difficult to use. The gas tended to remain "stuck" in the small measure, and it was difficult to make it travel upwards into the cylinder. We therefore decided to perform the tests with the bigger cylinder (diameter 15.0 mm) first to see whether we were able to obtain the results published by Ingenhousz.</p> <p>Graph: Fig. 9 Cylinder with rubber bands. Set-up used for calibration and for reading the results of the eudiometric experiments</p> <p>Because the cylinder was narrower and higher, the gas indeed travelled upwards more slowly inside the cylinder. An individual operator has enough time after inserting the NO with the "small measure" to start shaking the cylinder before the NO and the sample of atmospheric air start mixing. The opening of the cylinder was small enough for the operator to use one's thumb to close it for shaking, so there was no need to use a stopper. This made the operation simpler to perform.</p> <p>Reading the result was done as follows. Having waited a minute after mixing the gases, the first rubber band is rolled to the position where the water and the remaining volume of gas in the cylinder meet. The second rubber band (which marks a volume of 2 measures) is held fixed. This is why the position of the band is marked with a permanent marker, as to be sure that it has not moved during the procedure. The distance between the first rubber band and the second one is measured and divided by the distance corresponding to one measure, as established during the calibration. When this number is subtracted from the two total measures, one gets the amount of remaining measures.</p> <p>Before performing the measurements using the HPF method, we first mixed the gases without shaking to have a baseline. First, a sample of atmospheric air was introduced with the small measure, then a sample of NO. Three consecutive measurements gave the same result of 1.44 measures. The same results were obtained when three consecutive measurements were made one another day. When the HPF method was followed, the average result was indeed around one measure. We performed six consecutive measurements. Four of them resulted in 1 measure. Two of them resulted in 0.95 measure. We have mentioned that the lowest result mentioned by Ingenhousz is 0.945 measures (1780, p. 367). Our replications seem to confirm that it would indeed have been possible for Ingenhousz to obtain this result. They also confirm the cited assessment of Cavendish that the test following the method of Ingenhousz generally results in one measure of gas remaining.</p> <hd id="AN0185990916-14">Discussion</hd> <p>In this section, we discuss the experience of the students and the benefits of incorporating this type of experiments in undergraduate chemistry education. We do this by connecting our experience and those of the students to the existing literature. Before doing so, we first provide more details on the way we gained information about the students' experiences, the role and didactic formation of the teachers, and the method that was followed during the replications.</p> <hd id="AN0185990916-15">Preliminary Information: Interviewing and Teaching Method</hd> <p>As discussed at the beginning of Section 4.1, two series of experiments were performed. First, a preliminary set of experiments was performed in collaboration with MA students in the context of an optional course on the history of chemistry. After finishing the series of experiments, the students had to write a small report, in which they had to answer the following questions:</p> <p></p> <ulist> <item> How would you compare the experimental work you have performed for this course with the kind of lab work you had to do in other courses? Are there differences and if so, what are they?</item> <p></p> <item> What did you find surprising?</item> <p></p> <item> What have you learned from working on the replication? If you feel you have not learned anything, what do you think could be changed in order to make this into a more informative experience?</item> <p></p> <item> Would it be valuable to make this kind of replication experiments part of the chemistry curriculum at the university? Why (not)?</item> </ulist> <p>In the year following these preliminary experiments, a more extensive series of experiments was performed in collaboration with two BA students (see Section 4.1). After finishing the experimental work, Dr. Beck did a debriefing with the two students and asked them about their experience, by posing the same questions as those that had been given to the MA students. As co-authors, the BA students read the paper before (re)submitting. They were explicitly asked to check whether the points mentioned here correctly reflected their views and experiences.</p> <p>During the entire process, the students were guided by Pieter Beck. Dr. Beck is a postdoctoral researcher working in the field of integrated history and philosophy of science (IHPS), with a focus on the history of eighteenth century chemistry, specifically its experimental side. He has a teacher's degree and co-teaches an optional history and philosophy of science course for students from the science and engineering faculties. He also co-teaches courses on epistemology and philosophy of science to philosophy students. He worked alongside the students in the lab during the replication process. Before the start of the experimental work, he provided the students with a short introduction on the historical material discussed in Sections 2 and 3 of this paper. Prof. Dr. Mieke Adriaens provided general supervision for the process and taught the students specific analytical procedures when they were necessary for the research (cf. infra). She has been a professor at Ghent University since 2001, and teaches several courses, both at BA and MA level, with a focus on analytical methods. She is also the main teacher of the aforementioned "History of Chemistry" course.</p> <p>As discussed in Section 4.1, the experimental work with the MA students was aimed primarily at developing a proof of concept. The work focused mostly on developing a method for producing NO and doing some preliminary experiments with a simplified set-up. Based on his research on the sources, Dr. Beck provided the students with a general concept for an experimental set-up. They were given the assignment to translate this concept into a workable set-up, based on the glasswork and material available in the lab. Problems already arose during the attempt to produce NO. Students were encouraged to identify the problem and find a solution themselves. This turned out to be more difficult, as 4 of the total 6 h in the lab were devoted to this. We will discuss these problems in Section 5.2.</p> <p>The two BA students participated in the experimental work as part of their bachelor's project. In their final BA year, students are expected to do an "internal" internship at the university by participating in the ongoing research of one of the research groups. They have to do two such internships, one focused on analytic chemistry and one focused on organic chemistry. The two students choose our project for their analytic chemistry internship. The bachelor's project is seen as the culmination of the BA's trajectory related to the acquisition of experimental skills. In each year of their BA, the students have a course titled "Experimentation in Chemistry," in which they are taught relevant skills, techniques, and attitudes. The bachelor's project is an addition to this and aims to provide the students with a taste of "real scientific research" and is seen as both a way to put the acquired skills to work and as a way to acquire extra specific experimental skills. As students were expected to perform two internships, this allowed us to further ask the students about the difference they perceived between the work on the replication and the experimental work performed in the other internship. This will be discussed in Section 5.2.</p> <p>The context of the bachelor's project also meant that there was more time to experimental work. In total, 46 h were spent in the lab. At the beginning of the process, Pieter Beck gave the students an introduction about eighteenth century "nitrous air" eudiometers, the general principle behind these eudiometers, and the work that had been performed by the MA students the year before.[<reflink idref="bib8" id="ref71">8</reflink>] They were explicitly informed that the project was intended to be an open-ended investigation during which they could and should provide input. After repeating the experiments performed by the MA students the previous year, it became clear that there was a discrepancy between the results obtained by that method and the results published by Ingenhousz. We agreed to make this discrepancy the starting point of our experimental research, with the aim to explain the discrepancy and to find out whether it would be possible to replicate Ingenhousz's results by changing the experimental method. Dr. Beck worked in the lab alongside the students and performed further historical research if this was necessary in the context of the replication. Finding and analyzing relevant primary sources were the responsibility of Dr. Beck, but the students had access to scans of the primary sources so that they could consult them if they wanted. Changes in the set-up and the procedure were always discussed with the students, while keeping an eye on finding a balance between practicality, reliability, historical accuracy, and of course safety. The question of finding a balance between historical accuracy and other factors provided Dr. Beck with a context to teach the students about historical details, but also to teach them several aspects related to the issue of the nature of science (NOS). This will be discussed in more detail in Section 5.2.</p> <p>Throughout the process, students were encouraged to formulate hypotheses regarding the cause(s) for the discrepancy between our results and those of Ingenhousz and to think of ways to test these hypotheses. The latter often involved using contemporary analytical techniques and thus provided an opportunity for prof. Adriaens to teach these techniques to the students.</p> <hd id="AN0185990916-16">Benefits for Science Education</hd> <p>The replication of the eudiometer can be seen as an example of what Hasok Chang calls "complementary experiments," a specific type of historical experiments with several benefits for science education. Complementary experimentation is the practical side of "complementary science," a specific way of doing history and philosophy of science (HPS) which focuses on retrieving forgotten phenomena, theories, and questions. As its name suggests, it is a practice meant to complement existing scientific practice, in which progress often means that certain questions or phenomena become forgotten or at least less central (so-called Kuhn loss) (Chang, [<reflink idref="bib7" id="ref72">7</reflink>], pp. 333–334). Chang discusses several ways in which complementary experiments help science education. The following benefits mentioned by Chang were also observed in our work: complementary experiments help students develop their creative and critical thinking skills, and they can help in NOS teaching (Chang, [<reflink idref="bib7" id="ref73">7</reflink>], 335–337). We will add two further benefits not mentioned by Chang that are specific to the work with the eudiometer. Finally, we were able to use the replication work to teach the students specific experimental and analytical techniques. Based on our experience, we believe there are benefits to using complementary experimentation as a context to teach contemporary experimental techniques.</p> <p>The first benefit that we would like to discuss is "the cultivation of original and independent thinking, and a critical and inquiring attitude in students" (Chang, [<reflink idref="bib7" id="ref74">7</reflink>], 335). In the science education literature, the use of historical experiments has often been mentioned as a useful tool for enabling inquiry-based learning. Metz and Stinner argue that in practice, inquiry-based approaches not always succeed in attaining the goals of inquiry-based education as originally formulated by Schwab ([<reflink idref="bib34" id="ref75">34</reflink>]), namely for "students to encounter phenomena, discuss possibilities, debate the feasibility and validity of different problems, consider methodologies, apportion responsibility, write reports, account for and resolve discrepancies, and then arrive at a consensus" (Metz & Stinner, [<reflink idref="bib27" id="ref76">27</reflink>], p. 615–616).</p> <p>In the first series of experiments performed with MA students, they were already confronted with a problem from the start when they noticed that the "nitrous air" that they had produced did not react with atmospheric air. We encouraged them to solve this problem themselves, by debating possible explanations for the failure and proposing changes to the set-up to test these explanations. It turned out that the problem was that they had put the plastic tube immediately under the glass jar and had thus unknowingly also collected the N<subs>2</subs> which was pushed out of the Büchner flask by the NO and NO<subs>2</subs>. Several students reported in their reflection essay that they were surprised by the initial failure to produce and collect NO and the fact that it took a while to figure out what was going wrong, even though it was so straightforward in hindsight. Many students contrasted this experience with the type of experiments they had to perform during their education. The main contrast that was explicitly mentioned by several students was that in the case of the replication, it was necessary to think about the experimental set-up itself, which otherwise was taken as a given.</p> <p>In the more extended work with the BA students, the process itself centered around explaining the encountered discrepancy between the results of our first experiments and those published by Ingenhousz. The students were again encouraged to come up with possible explanations themselves, to translate these explanations into testable hypotheses, and to propose ways to test these hypotheses. Sometimes, the students disagreed about the feasibility and validity of certain proposals. Instead of resolving the difficulty for them, we took this as an opportunity for them to exercise their critical reasoning skills and asked them to try to find a consensus by making the reasons behind their disagreement more explicit, and to see whether they could find a common ground. We will provide a concrete example of a hypothesis proposed by a student and a method of testing this below, when we discuss the use of contemporary analytic techniques.</p> <p>The performance of these non-standard experiments also meant that it was sometimes necessary to improvise due to the lack of ready-made equipment. Rather than being an impediment, this was regarded by the BA students as a positive challenge. It stimulated their creative thinking, which in turn made them more confident to propose further avenues for investigation.</p> <p>The contrast between the type of experiments performed in this project and the more "ready-made" experiments encountered in other courses was also mentioned by the BA students. After finishing her second internship for the bachelor's project in another research group, one of the BA students said she missed the sense of creativity and responsibility she had felt during the work on the replication. Her description of the experimental work performed in the second internship corresponds to the description of failed inquiry-based methods mentioned by Metz and Stinner: "While the emphasis was purportedly on process, students simply followed 'recipes' from lab manuals and memorized facts and laws" ([<reflink idref="bib27" id="ref77">27</reflink>], p. 615).</p> <p>This brings us to the second benefit of this type of experimental work, namely that it gives "students an improved sense of the nature of scientific practice," which "should be taken as part of the general argument that HPS helps NOS teaching" (Chang, [<reflink idref="bib7" id="ref78">7</reflink>], 335). According to Chang, historical experiments have the benefit of "teach[ing] students (and teachers) that things are more complicated that they had been led to believe" ([<reflink idref="bib7" id="ref79">7</reflink>], p. 322). This counters the tendency of oversimplifying things in so-called normal science education (Chang, [<reflink idref="bib7" id="ref80">7</reflink>], p. 322). Above, we have shown how the work on the replication showed that the simple formula of the reaction of NO with O<subs>2</subs> to form NO<subs>2</subs> was too simple to explain what happened in the eudiometer, and that side reactions had to be taken into account. But even then, although we were able to use the side reactions to see <emph>that</emph> a result as low as 0.95 measure was theoretically possible, even at the end of our work we were not able to explain <emph>why</emph> the specific set-up used and manipulations performed by Ingenhousz enabled him to attain this result. With regard to the process of inquiry, complementary experiments teach students "that the actual process of scientific inquiry is not fully reflected in the simplifications and distortions made in normal science education for the sake of effective communication and efficient learning" (Chang, [<reflink idref="bib7" id="ref81">7</reflink>], 335; see also Niaz, [<reflink idref="bib28" id="ref82">28</reflink>]). The difficulties the MA students encountered when trying to produce NO, their surprise at their own difficulty of locating and solving the problem, and their realization that they had not been trained to reflect on the experimental set-up itself can again be mentioned as examples.</p> <p>Specifically related to NOS, we found extra benefits in our replication work which are not mentioned by Chang, but which further confirm arguments made by Mansoor Niaz. Niaz has done much work to argue for the benefits of incorporating history and philosophy of science in chemistry education, especially with regard to NOS (Niaz, [<reflink idref="bib29" id="ref83">29</reflink>]). More specifically, we argue that the replication can be used to illustrate the following aspects of NOS mentioned by Niaz: "competition among rival theories" ([<reflink idref="bib29" id="ref84">29</reflink>], p. 47), "different interpretations of the same experimental data leading to controversies" (2015, pp. 48–49), and "the role of refutation or falsification" ([<reflink idref="bib29" id="ref85">29</reflink>], pp. 50–51). We shall start with falsification. As Niaz notes, "[m]ost philosophers of science would agree that the relationship between theory and experiment is complex and a single experiment cannot falsify a theory" ([<reflink idref="bib29" id="ref86">29</reflink>], p. 50). When confronted with an anomalous result, scientists typically do not immediately see these as a refutation of their background theory, but will look for possible explanations of this anomalous result. The first place to look for an explanation will be to check whether the experimenter made any mistakes or whether there were malfunctions in components of the experimental set-up.</p> <p>In the history and philosophy of science course that dr. Beck teaches to science students, it becomes clear that the idea that falsification is essential in the definition of science is still a reference for many science students. Dr. Beck begins the course by asking the students to provide their own definition of what science is. This mostly results in a blank stare from the students, but the few brave students that do reply often reply that "science should be falsifiable." Failures encountered during the replication process (the failure to produce NO being a good case in point) provide a good, concrete instance to explain the problem with naïve falsificationism to students. The failed experiment is not seen as a falsification of the background theoretical knowledge that dissolving copper in nitric acid procures nitrogen monoxide and that nitrogen monoxide reacts with the oxygen in the air to form nitrogen dioxide. Instead, students intuitively see that it makes more sense to first check whether something has gone wrong in the experiment.</p> <p>The points regarding competition between rival theories and the fact that experimental data can be interpreted differently will be taken together under the banner of underdetermination. As we have discussed in Section 2, Priestley explained the "nitrous air test" based on the phlogiston theory. This provided us with a context to teach the students about the phlogiston theory itself, and Priestley's rivalry with Lavoisier. We could also show that observations made during the eudiometric procedure could be explained as well by the phlogiston theory as by Lavoisier's theory, providing a concrete example of underdetermination.</p> <p>The final benefit encountered during the replication process was that they provided a good context for the students to learn about procedures and operations not directly related to the nitrous air eudiometer. At the beginning of our replication process, we performed an analysis on a sample of the NO that we had produced to be sure about its purity. The students were asked to bring the sample to the colleague performing the analysis and to ask for information on how the analysis works. At one point, we were considering the role of dissolved oxygen in the water as a possible explanation for Ingenhousz's results, as this was invoked by Usselman, Leaist, and Watson to explain the deviating results of the experiments performed by Dalton (2008, p. 109). This was taken by prof. Adriaens as an opportunity to teach the students about the Winkler titration, which they subsequently performed themselves. When we had found that the side reactions taking place provided a probable explanation for the results obtained by Ingenhousz, one of the students noted that in the scenario where all the NO<subs>2</subs> reacts with NO to form N<subs>2</subs>O<subs>3</subs>, only HNO<subs>2</subs> will be found in the water. In the other cases, both HNO<subs>2</subs> and HNO<subs>3</subs> will be found. The student suggested to perform a titration with an automatic potentiometric titrator (HI931 (Hanna Instruments®)) to compare the water in the cylinder in the case of not shaking the cylinder and in the case of following the HPF method. The student was already familiar with the instrument. He was given permission to pursue this avenue and was given further information by Tine Veevaete and prof. Adriaens on the specific procedure to be followed in this case. He was then asked to demonstrate the procedure to his co-student, who was not yet familiar with using the automatic potentiometric titrator. Even though the results of these analyses did not help in explaining our results, the students did learn techniques which are relevant in a contemporary context. By learning these techniques in the context of the ongoing research on the replication, the students had a direct goal in mind as to why learning these techniques would be relevant. This added to their motivation. A final benefit of the historical experiments discussed in this article is thus that they can be combined with contemporary analytical techniques in a pedagogical setting, to provide a specific context in which these techniques can be taught and practiced.</p> <hd id="AN0185990916-17">Acknowledgements</hd> <p>During our research, we benefited from the help of several colleagues. We would firstly like to thank Tine Veevaete (Department of Chemistry) for always providing us with the necessary materials and her assistance with the automatic pH titrations. Many thanks to Pieter Surmont (Department of Organic and Macromolecular Chemistry) for analyzing our NO samples. Special thanks to Thibault Martre and Tim Gijs from the Central Technical-Scientific Workshop (Faculty of Sciences) for their incredible work on the replication of the eudiometer. Dr. Beck would like to thank the chemists with whom he collaborated, and Prof. Adriaens in particular, for being so open-minded and welcoming towards this peculiar historian/philosopher interested in performing experiments.</p> <hd id="AN0185990916-18">Author Contribution</hd> <p>This article is the result of fully collaborative work. Dr. Pieter T. L. Beck performed the necessary historical research and developed the general conception of the research and the initial experimental set-up. Prof. Dr. Adriaens provided technical and theoretical supervision during the entire process. Prof. Dr. Adriaens, Ruby Cornand, and Wannes De Turck provided crucial practical and technical input for redesigning the experimental set-up during the course of the research, as described in the article. The experimental work was performed in collaboration by all authors. The first draft of the manuscript was written by Dr. Beck. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.</p> <hd id="AN0185990916-19">Data Availability</hd> <p>The authors declare that the chemical data supporting the findings of this study are available within the paper. Should any raw data files be needed they are available from the corresponding author upon reasonable request. The reports of the MA students mentioned in section 5 are kept in a local repository and cannot be disclosed due to privacy reasons. They are available from the corresponding author upon reasonable request and depending on the permission of the authors of the report.</p> <hd id="AN0185990916-20">Declarations</hd> <p></p> <hd id="AN0185990916-21">Conflict of Interest</hd> <p>The authors declare that they have no conflict of interest.</p> <hd id="AN0185990916-22">Publisher's Note</hd> <p>Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.</p> <ref id="AN0185990916-23"> <title> References </title> <blist> <bibl id="bib1" idref="ref11" type="bt">1</bibl> <bibtext> Beretta, M. (2000). Pneumatics vs. "aerial medicine": Salubrity and respirability of air at the end of the eighteenth century. In F. & L. F. Bevilacqua & L. Fregonese (Red.), Nuova Voltiana: Studies on Volta and his times (pp. 49–71). U. Hoepli.</bibtext> </blist> <blist> <bibl id="bib2" idref="ref20" type="bt">2</bibl> <bibtext> Boantza VD. 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American Journal of Physics. 2010; 78; 1: 5-6. 10.1119/1.3238470</bibtext> </blist> <blist> <bibtext> Niaz M. Chemistry education and contributions from history and philosophy of science. 2015; Springer</bibtext> </blist> <blist> <bibtext> Priestley, J. (1772). Observations on different kinds of air. Philosophical Transactions of the Royal Society of London, 62, 147–264.</bibtext> </blist> <blist> <bibtext> Priestley, J. (1774). Experiments and observations on different kinds of airs. J. Johnson.</bibtext> </blist> <blist> <bibtext> Priestley, J. (1790). Experiments and observations on different kinds of airs (1–3). Printed by Thomas Pearson.</bibtext> </blist> <blist> <bibtext> Schaffer, S. (1990). Measuring virtue: Eudiometry, enlightenment and pneumatic medicine. In A. Cunningham & R. French (Red.), The Medical Enlightenment of the Eighteenth Century (pp. 281–318). Cambridge University Press.</bibtext> </blist> <blist> <bibtext> Schwab JJ. The teaching of science as inquiry. 1962; Harvard University Press</bibtext> </blist> <blist> <bibtext> Settle TB. An experiment in the history of science. Science. 1961; 133; 3445: 19-23. 10.1126/science.133.3445.19</bibtext> </blist> <blist> <bibtext> Usselman, M. C, Leaist, D. G, & Watson, K. D. (2008). Dalton's disputed nitric oxide experiments and the origins of his atomic theory. ChemPhysChem, 9(1), 1. https://doi.org/10.1002/cphc.200700707</bibtext> </blist> </ref> <ref id="AN0185990916-24"> <title> Footnotes </title> <blist> <bibtext> The development of the concept "gas" was long and difficult. Up until the first half of the eighteenth century, the term "air" was mostly used to refer to gases. In writings from this period, it is often not clear whether these "airs" were seen as specific substances or whether they were seen as modifications of atmospheric air. For a discussion and overview of the development of the concept of "gas," see Crosland ([12]). In what follows, we will use the terms "air(s)" and "gas(ses)" interchangeably. The distinction between nitrous acid (HNO<subs>2</subs>) and nitric acid (HNO<subs>3</subs>) was not yet made at this time. In what follows, when we cite or refer to primary source material, the term "nitrous acid" should be understood as referring to nitric acid in the present sense of the word (see Eklund, [13], p. 33).</bibtext> </blist> <blist> <bibtext> Ingenhousz writes that the tube is 18–20 Paris inches long. According to Gyllenbok's <emph>Encyclopaedia</emph><emph>of Historical Metrology, Weights and Measures</emph>, in the period from 1668 to 1793, one Paris inch (<emph>pouce</emph>) is equal to 27.0699526 mm in the metric system (Gyllenbok, [17], p. 1092). Thus, 18–20 Paris inches correspond to 487.3–541.4 mm. In what follows, we will use Gyllenbok's values to transpose the Paris inches to contemporary measures.</bibtext> </blist> <blist> <bibtext> In a later publication, he would state that shaking the tube for twelve to fifteen seconds suffices and that shaking it longer does not make a difference (Ingenhousz, [22], pp. 354–355).</bibtext> </blist> <blist> <bibtext> In line with the Bologna reforms, which aimed to streamline national educational systems in Europe (Kehm & Teichler, [24]), Flemish universities have adopted a BA-MA structure, in which students first follow a 3 years Bachelor program (BA), followed by a 1 or 2 years Master program (MA). At Ghent University, the Master program is 2 years. The MA students involved in the replication took up the optional "History of Chemistry" course in the first year of their MA studies.</bibtext> </blist> <blist> <bibtext> The students were: Baldwin Bontinck, Bram Daelman, Jana Floreal, Ward Flyps, Lieselot Nerinckx, Pauline Rooms, Tom Sleeckx, Mark Smet, Febe Van Broeck, Johannes Van Overmeire, Marthe Vermeulen.</bibtext> </blist> <blist> <bibtext> According to <emph>Allen's Astrophysical Quantities</emph>, the percentage of oxygen in the atmosphere is 20.95% (Cox, [11], p. 258).</bibtext> </blist> <blist> <bibtext> Such an effect was not observed when we used the graduated cylinders. We therefore did not take this precaution in those experiments. In Ingenhousz's procedure, this was taken into account by putting the great measure into the bigger cylinder filled with water. Ingenhousz mentioned to his reader that when taking the reading, it was always necessary to make sure that the water inside the great measure was level with the water outside (Ingenhousz, [19], p. 277).</bibtext> </blist> <blist> <bibtext> In this aspect, the project resembles Hasok Chang's work with undergraduate students on the history of chlorine. Chang used a method he called a "method of inheritance" or "inherited research work" in which students build on the work that other students had performed the previous year (Chang [6], 418–419).</bibtext> </blist> </ref> <aug> <p>By Pieter T. L. Beck; Ruby Cornand; Wannes De Turck and Mieke Adriaens</p> <p>Reported by Author; Author; Author; Author</p> </aug> <nolink nlid="nl1" bibid="bib18" firstref="ref1"></nolink> <nolink nlid="nl2" bibid="bib16" firstref="ref8"></nolink> <nolink nlid="nl3" bibid="bib33" firstref="ref9"></nolink> <nolink nlid="nl4" bibid="bib15" firstref="ref10"></nolink> <nolink nlid="nl5" bibid="bib25" firstref="ref14"></nolink> <nolink nlid="nl6" bibid="bib30" firstref="ref17"></nolink> <nolink nlid="nl7" bibid="bib31" firstref="ref19"></nolink> <nolink nlid="nl8" bibid="bib10" firstref="ref24"></nolink> <nolink nlid="nl9" bibid="bib32" firstref="ref25"></nolink> <nolink nlid="nl10" bibid="bib26" firstref="ref31"></nolink> <nolink nlid="nl11" bibid="bib19" firstref="ref39"></nolink> <nolink nlid="nl12" bibid="bib22" firstref="ref40"></nolink> <nolink nlid="nl13" bibid="bib21" firstref="ref47"></nolink> <nolink nlid="nl14" bibid="bib23" firstref="ref48"></nolink> <nolink nlid="nl15" bibid="bib20" firstref="ref50"></nolink> <nolink nlid="nl16" bibid="bib14" firstref="ref53"></nolink> <nolink nlid="nl17" bibid="bib36" firstref="ref56"></nolink> <nolink nlid="nl18" bibid="bib34" firstref="ref75"></nolink> <nolink nlid="nl19" bibid="bib27" firstref="ref76"></nolink> <nolink nlid="nl20" bibid="bib28" firstref="ref82"></nolink> <nolink nlid="nl21" bibid="bib29" firstref="ref83"></nolink>
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  Data: Replicating the Fontana-Ingenhousz Eudiometer: Incorporating Historical Experiments in Undergraduate Chemistry Education
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  Data: <searchLink fieldCode="AR" term="%22Pieter+T%2E+L%2E+Beck%22">Pieter T. L. Beck</searchLink> (ORCID <externalLink term="http://orcid.org/0000-0003-4788-4715">0000-0003-4788-4715</externalLink>)<br /><searchLink fieldCode="AR" term="%22Ruby+Cornand%22">Ruby Cornand</searchLink><br /><searchLink fieldCode="AR" term="%22Wannes+De+Turck%22">Wannes De Turck</searchLink><br /><searchLink fieldCode="AR" term="%22Mieke+Adriaens%22">Mieke Adriaens</searchLink>
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  Data: <searchLink fieldCode="SO" term="%22Science+%26+Education%22"><i>Science & Education</i></searchLink>. 2025 34(3):1703-1729.
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  Data: Springer. Available from: Springer Nature. One New York Plaza, Suite 4600, New York, NY 10004. Tel: 800-777-4643; Tel: 212-460-1500; Fax: 212-460-1700; e-mail: customerservice@springernature.com; Web site: https://link.springer.com/
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  Data: 27
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  Data: <searchLink fieldCode="DE" term="%22Undergraduate+Students%22">Undergraduate Students</searchLink><br /><searchLink fieldCode="DE" term="%22College+Science%22">College Science</searchLink><br /><searchLink fieldCode="DE" term="%22Science+Education%22">Science Education</searchLink><br /><searchLink fieldCode="DE" term="%22Chemistry%22">Chemistry</searchLink><br /><searchLink fieldCode="DE" term="%22Measurement+Equipment%22">Measurement Equipment</searchLink><br /><searchLink fieldCode="DE" term="%22Laboratory+Procedures%22">Laboratory Procedures</searchLink><br /><searchLink fieldCode="DE" term="%22Science+Experiments%22">Science Experiments</searchLink><br /><searchLink fieldCode="DE" term="%22Science+History%22">Science History</searchLink><br /><searchLink fieldCode="DE" term="%22Creative+Thinking%22">Creative Thinking</searchLink><br /><searchLink fieldCode="DE" term="%22Critical+Thinking%22">Critical Thinking</searchLink><br /><searchLink fieldCode="DE" term="%22Scientific+Principles%22">Scientific Principles</searchLink>
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  Data: 10.1007/s11191-024-00533-z
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  Data: 0926-7220<br />1573-1901
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  Data: In this article, we discuss the replication of a forgotten chemical instrument in the context of undergraduate chemistry education. Together with students, we have attempted to replicate an eighteenth century "eudiometrical" procedure. Eudiometry was the practice of measuring the "goodness" of the air by looking at the volume reduction of a sample of air when it reacts with specific substances. Our replication of a eudiometer can be seen as an example of what Hasok Chang calls "complementary experiments," a specific type of historical experiments with several benefits for science education. We show how the replication work helped students develop their creative and critical thinking skills, and also facilitated NOS teaching. Moreover, we were able to use the replication work to teach the students contemporary experimental and analytical techniques. Based on our experience, we believe there are benefits to be found in teaching contemporary techniques in the context of complementary experimentation.
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