What Can a Nineteenth Century Chemistry Textbook Teach Twentieth Century Chemists? M. Elizabeth Derrick Valdosta State College, Valdosta. GA 31698 In 1805 in London, Jane Marcet published anonymously a chemistry textbook entitled "Conversations on Chemistry." Two American editions of this textbook. one oublished in 1809 and the other in 1833, came into my possession several vears ago. As I orepared a historical manuscriot (1) about the anchor, I became interested in the textbook itself. I t occurred to me that although this early textbook had little to say to 20th century chemists about chemistry, i t did have something of value to say to 20th century chemists about how they teach chemistry. As its title suggests, "Conversations on Chemistry" is written in the form of a dialog. In the preface, Jane Marcet explicitly stated that she was writing the hook to provide women with a method of educating themselves in chemistry and that she had chosen the dialog style because she herself had learned chemistrv throueh conversations with a friend ( 2 ) .Although ~ a r c e t ' swriting would indicate that she was an intelligent, educated woman, she had no formal education in chemistry. She did attend lectures at the Royal Institution in London and there became acquainted with Sir Humphrey Davy. The hook was used as a textbook in England and America throughout the 19th century (3). I t was frequently revised, appearing in some 16 London editions and a t least 15 American editions as well as two French translations. "Conversations on Chemistry" was the first of a numher of "Conversations" textbooks on a variety of subjects that Marcet published (4). The textbook is delightfully readable. There are three characters: Mrs. B., the teacher, and Caroline and Emily, hoth students. The three characters have personalities and quickly become real people to the reader. Mrs. B. firmlv . . directs the conversations, asking questions, carrying out ex~~eriments, skillfully leading the students to make observations and reach conclusions~She allows the students to lead her momentarily on tangents, but rarely digresses far from the point of the lesson. She admits when she has reached the limits of her expertise. Mrs. B. is imperturbable, as illustrated by this passage (5),which follows some experiments with sulfuric acid. Caroline. I have very unintentionally repeated the experiment on my gown, by letting a drop of the acid fall upon it, and it has will never wash out. made a stain, which, I supmse, .. Mrs. B. No, certainly; for, before you can put it into water, the spot will become a hole, as the acid has literally burnt the muslin. Caroline. So it has indeed! Well, I will fasten the stopper and put the bottle away, for it is a dangerous substance-Oh, now I have done worse still, for I have spilt some on my hand! Mrs. B. It is then burned, as well as your gown, for you know that oxygen destroys animal as well as vegetable matter: and as far as the decomposition of the skin of your finger is affected, there is no remedy; hut, by washing it immediately in water, you will dilute the acid, and prevent any further injury. Caroline and Emily have different personalities. Emily is a model student. She can be relied upon to ask the right Presenred at the Eighth Biennial Conference on Chemical Education. University of Connecticut, August 1984
questions and give correct answers. Caroline, on the other hand, is more spontaneous and imaginative. She is more likely to steer the lesson off course. Some idea of the students' personalities can he gleaned from the following passage (6): Em,/,. l'hrre is a poison called wrdigris, which formson brass
and roppw whm nor kept very clean; and this. I have heard, is an
ohjectron ro rhesa metnls being made into kitchen utmsils. Is this poison likewise occasioned by. oxwen? .. Mrs. B. It is produced by the intervention of oxygen; for verdigris is a compound salt formed by the union of vinegar and copper; it is of a beautiful green color, and much used in painting. Emily. But, I believe, verdigris is often formed on copper when no vinegar has been in contact with it. Mrs. B. Not real verdigris, but compound salts, somewhat resembling it, may he produced by the action of any acid on capper. (The 1833 edition has been changed here to read "other acids.") There is a heautiful green salt produced by the combination of cohalt with muriatic acid, which has the singular property of forming what is called sympathetic ink. Characters written with the solution are invisible when cold, hut when gentle heat is applied, they assume a fine blueish green colour. Caroline. I think one might draw very curious landscapes with the assistance of this ink; I would first make a water colour drawine of a winter scene. in which the trees shall he leafless and the grass smrrrly grrrn; 1 would then trace all the verdure wirh the ink, nnd whrnrvrr 1 chow to create sprmg, I should hold ~nvrzrhl~ it before the fire, and its warmth would cover the landscape witha rich verdure. ~
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The textbook is interesting in a historical sense. While the experimental observations are sound. the intemretations. as is gpparent from the previous quotations, ar; not those of the 20th century. The textbook discusses heat in terms of caloric; physicaland chemical changes are spoken of in terms of attraction of cohesion and attraction of comoosition. respectively; the list of elementary substances in the 1809 edition includes, along with a number of elements, caloric and several compounds. The 1833 edition contains a revised listing of simple bodies divided into several classes, all of rr,hich are elements except for the irnptmderahlr agents calw ric, light, and rlerrricity. There are many other examples of early 19th century chemical theory. This textbook, however, is interesting in quite another sense. Through her teacher. Mrs. B.. and her textbook. Jane Marcet accomplished in theearly 19th century much of what we, in the 20th centurv, .. sav . we ought to be doing as teachers and as writers. Perhaps we can learn something from her example. In recent years chemical educators have discussed the implications modern learning theories hold for teaching and teaching materials. piagetian theory has been of partrcular interest (7-9). In a recent paper, "What Can Science Educators Teach Chemists About Teaching Chemistry," Herron (10) has discussed two learning theories. In Learning Theory A the learners are given what they must learn. Mastery of content and practice are the primary goals of this approach. In Learning Theory B "the learners create for themselves what is learned" (10). Mastery of content as well as underVolume 62
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standing are primary goals. Herron suggests that while we philosophically adhere to Theory B we, in fact, use materials and often teach according to Theory A. In another recent paper Herron discusses the implications of learning theory for textbooks (111. A belief in Theory B has led some chemical educators to discuss the use of learning cycles, the need to take students, by means of concrete examples, from where they are in their present understanding to new experiences and ultimately to help them reach a new and perhaps more abstract understanding of the subject. Demonstrations, laboratory experiments, and the use of everyday and industrial examples of chemistry have been discussed as important in the facilitation of these learning cycles. A skillful and imaginative teacher is needed if the goal is to guide students to learn for themselves, as opposed to telling students what they need t o
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Jane Marcet accomplished these goals in her textbook without t h e advantage of modern learning theories. Throughout the book the conversations (chapters) are of moderate length designed to develop a particular topic. They often end with an admonition to the students to review a particular concept before the next session and a comment about the topic of the next conversation. There is considerable interaction between Mrs. B. and the students. She often introduces topics using something familiar to the two girls, eliciting responses from them, then introducing new ideas, followed by experiments using unfamiliar materials, and finally helping them to make comparisons and draw conclusions. She often concludes a conversation with an interesting practical application of something that has heen discussed. example ofthis approach can be seen in the first conver. sation where the ideas of elementary substances and chemical change are introduced. After a general introduction to the study of chemistry the following exchange occurs (12): Mrs. B. . .., hut you must observe, that the various bodies in nature are composed of certain elementary principles, which are not very numerous. Carolme. Yes; I know that all bodies are composed of fire, air, earth, and water; I learnt that many years ago. Mrs. B. But you must endeavor to forget it. I have already informed you what a great change chemistry has undergone since it became a regular science.. . . Far an elementatybody is one that cannot be decomposed, that is separated into other substances; and fire, air, earth, and water, are all of them susceptible of decomposition. Emdy. I thought that decomposing a hody was dividing it into its minutest pa& And if so, I do notunderstand why an elementary substance is not capable of being decomposed, as well as any other. Mrs. B. You have misconceived the idea of Decomposition; it is verv differentfrom mere division: the lattersimolv . .reduces a bodv into parts, but the former separates it into the various ingredients, or materials of which it is composed. If we were to take a loaf of bread, and separate the several ingredients of which it is made, the flour, the yeast, the salt, and the water, it would be very different from cutting the loaf into pieces, or crumbling it into
.
Emily. I understand you now very well.. . Caroline. But flour, water, and the other materials of bread,
according to your definition, are not elementary substances? Mrs. B. No my dear; I mentioned bread rather as a familiar comparison,to illustrate the idea, than as an example. The conversation continues as the students are introduced to some additional terminology including physical and chemical changes. Bread is used again as a n example. Shortly, Mrs. B. further illustrates this conversation with a n experiment. This and other experiments are described in such a way that the reader experiences the experiment. There are, in fact, numerous illustrations in the hook of equipment used (13).
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Mrs. B. . . . If, for instance, I pour on the piece of copper, contained in this glass, some of this liquid (which is called nitric acid) for which it has a strong attraction, every particle of the copper will combine witha particle of acid, and together they will form a new hody, totally different from either the copper or the acid. Do you notice the internal commotion that already begins to take place?. . . Emily. The acid . .. appears to be very rapidly dissolving the canner. r r - - ~ ~
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Mrs. B. By this means it reduces the copper into more minute parts, than could possibly he done hy any mechanical power. But as the acid can act only on the surface of the metal, it will be some time before the union of these two bodies will he completed. You may, however, already see bow totally different this compound is from either of its ingredients. It is neither eolourless like the acid, nor hard, heavy, and yellow like the copper, If you tasted it, you would no longer oerceive the sourness of the acid. It has at present the appear&; of a blue liquid; but when the union is completed, and the water with which the acid is diluted is evaporated, it will assume the form of regular ehrystals, of a fine blue colour and perfectly transparent. Of these I can shew you a specimen, as I have prepared some for that purpose. Caroline. How very beautiful they are, in colour, form and transparency. Emily. Nothing can be more striking than this example of chemical attraction.
Although Mrs. B. performed this experiment herself, the students are mnetimes encouraged by her to carry out the experiments. Throughout the textbook the reader is referred back to earlier examples as Mrs. B. reminds the students of previous experiments. In the conversation on hydrogen the following Occurs (14): Emily. Water then, I suppose, when it evaporites and incorporates with the atmosphere, is decomoosed and converted into hydrogen and oxygen gasses? Mrs. B. Nomy dear; there you are quite mistaken; the decomposition of water is totally different from its evaporation; for in the latter ease (as you should recollect) water is only in astate of very minute division: and is merelv in the atmomhere. - susoended . . . without anv chemical combination.and without anv senaration of
fluid, as vapour, or under the solid form of ice. In our experiments on latent heat, you may recollect that we caused water successively to pass through these forms, merely by an increase or diminution of caloric,without employingany power of attraction, or effecting-any. decomoosition. As might be expected in a good textbook, advice is given to the students on studying the subject. When Emily expresses some fear that she may forget the new ideas she is being introduced to. Mrs. B. states (151, I would advise you to take notes, or, what would answer better still, to write down, after every lesson, as much of it as you can recollect. And, in order to give you a Little assistance, I shall lend you the heads or index, which I occasionallyconsult for the sake of preserving some method and arrangement in these conversations. Unless you follow some such plan, you cannot expe'ct to retain nearly all that you learn, how great soever be the impression it may make on you at first. Mrs. B. also chides Caroline when she expresses disinterest in a particular topic (16): You must not, however, he discouraged when you meet with some parts of a study less amusingthan others; it would answer no good purpose to select the most pleasing parts, since, if we did not proceed with some method, in order to acquire a general idea of the whole, wecould scarcelyexpect to takeinterest inany partieular subjects. Marcet did not shrink from including in her textbook references to the societal implications of science. At one point Emily asks why a new invention they have been dis-
cussing has not been more readily accepted. Mrs. B. responds (17): I b~lieve,my dear, that there are as many novelties attempted to h~ introd~aed,the adoption of which would he prejudicial to S I K I P ~ IIS ~ , there are of those whish would be beneficial tu it. The well informed, though by no means exempt from error, have an unquestionable advantage over the illiterate, in judging what is likely or not to prove serviceable; and therefore we find the former more ready to adopt such discoveries as promise to be really advantageous, than the latter, who, having no other test of the value of a noveltv but time and exoerience. at first moose . . its introduction. The well informed are, however, frequently diaappointed in their rnost sanyuineexpectationr,andthr preludiceruf thevulgar though they ottcn retard thepropressut knuulcdgc, yet sometimes, it must be admitted, prevent the propagation of error.
Jane Marcet's "Conversations on Chemistry" is a wellwritten, compelling, and interesting book. The reader becomes a participant in a classroom with two bright young women and a skillful teacher. Through this active participation the reader becomes a learner of chemistry. It seems that most chemistry textbooks tend to follow Learning Theory A.
Jane Marcet's textbook is a very early example of one that incorporates the philosophy of Learning Theory B. There are few modern examples. Literature Cited E., The Ho%n#on, 76, 38 11985). Also see Armstrong, E.V., J. CHew. 5.53l1988l. /,"conversationaonChemistry."Sidney's Pr*ufor Ineressecooke & co..
161 R e t 12).pp. 149-150. 171 Herron, J. D.,J. CHEM. EDUC., 52,146 (1975). 181 Beistol, D.W..J. CHEM. EDUC., 52,L5111975) 191 Herron, J. D.,J. CHEM. EDUC.55.165 (1978). (10)Herr0n.J. D.,J.CHEM. EDUC.,60,947(19831. (1,) Herron.J.D.,J.CHEM. EDUC..60.888l1983l. 1121 Ref lZl.o.4
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