THE QUANTITATIVE TREND IN GENERAL CHEMISTRY LABORATORY COURSES* Numerous typz'cal general chemistry laboratory texts published during the last forty years have been examined and studied as to the proportion of the quantitative experiments found in them. A n examinetion of the results shows that there has been very little agreement in the proportion of quantitative experiments which were included in freshman work, and 'that this proportion does not vary in any simple way m'th the date of pz~blication of the laboratory manual. A recent discussion among teachers of inorganic chemistry courses prompted the query: To what extent should quantitative experiments be employed in first-year laboratory work? I n an attempt to determine how far various schools go in this direction the author undertook a review of a number of laboratory manuals. It is hoped that the results of this research might be useful to others in planning freshmen laboratory outlines. The number of books examined included twenty-seven laboratory manuals covering the period of the last forty years. The institutions a t which these texts were written are among the most representative schools in the United States, but no attempt was made to make the list all inclusive. No doubt many important texts were overlooked, but a t some future time a more exhaustive study will be attempted. In the examination of a text, experiments were deemed quantitative when in the usual sense of the term they employed quantitative or physical measurements. The following list of findings is self-explanatory: Percentage of Quantitative Experiments in First-Year Laboratory Texts
1891 1891 1895 1899 1901 1902 1907 1911 1913 1914 1917 1921 1923 1924
SMITH and KELLER COOKE BARTLETI.
HULYER CONGDON DENNISand CLAW KAHLENBWG RANSOM NORT~
NEWELL BYER~
MCPH~RSON and HENDERSON BRAYand LATIMER KENDALL
U. of Penna. Harvard Dartmouth Wisconsin Drael Cornell Wisconsin Purdue Rutgas Boston Univ. Washington Univ. Ohio State Univ. U. of California Columbia
8 34 25 6 6 5 10 20 4
10 11 12 30 8
* Presented before the Division of Chemical Education at the 80th meeting of the American Chemical Society, Cincinnati, Ohio, Sept. 8-12, 1930. 307
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FEBRUARY, 1931
Ycor of Publication
DEMING and ARENSON HOLMES HBATAand BEISLER SCRLESINGER and LINK LONG,CHAMBERLIN, and ANDERSON SNEED and K m BR-EY and KELSEY BLANCHARD
BELCHERand COLBERT
RICHARDSON and S C A R L E ~ and DAY EVANS
Nebraska
Oberlin Florida Chicago
Lehigh Minnesota Yale De Pauw
Oklahoma Dartmouth Ohio
30
7 13 12 20 9 9 8 27 12 10
An examination of these results shows that there has been very little agreement in the proportion of quantitative experiments included in freshmen work. Before starting this investigation we felt that there would be a general upward trend in the amount of quantitative work done in freshmen courses. However, a chronological plot of these results would show as bad a set of peaks and depressions as any stock market report. The general average of the proportion of quantitative experiments is fifteen per cent. This figure may be used as an approximate guide, although excellent recent texts have been written with the number of quantitative experiments varying from ten to thirty per cent of the work. It is difficult to adequately explain differences,but some opinions may be hazarded. In the first place the writer of a text is, by his own training and research background, often influenced in his selection of experiments. To be sure he should not let this dominate his teaching methods, but it will unconsciously exert an infiuence. The whole spirit of certain institutions is more largely physical and quantitative than that of other colleges. A second reason for the variation is due to the differencesin previous training of the students. To students who have had a good course of elementary chemistry before entering college, a more advanced course of quantitative experiments is usually given. Beginning students must first be introduced to the subject before they can handle advanced experiments. Most laboratory texts are written to satisfy both classes of students and the usual procedure is merely to omit or include certain experiments according to the qualifications of the class. Hence it is almost impossible in examining a text which has, say, twenty per cent of its contents covering quantitative experiments to say that the freshmen course a t that institution has that same proportion of quantitative work. One section of the class may be doing fifty per cent quantitative work, while another section would prohably do only five per cent. The stress placed on quantitative work may also be determined to some extent by the subsequent courses to be taken by a student. There
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is a trend in several institutions to offer a course in pandemic chemistry to students who do not expect to major in chemistry. I t is too early to properly evaluate the results of such courses. However, it is the opinion of some of our older and more experienced teachers, that if you lead a student through a course in beginning chemistry without showing him the exactness of the science, you have done both student and science an irreparable injury. On the other hand, it is wise to offer a note of caution on the attempt to overdo quantitative work. If a student has not acquired sufficient skill to enter the quantitative stage of chemistry you may handicap him seriously by giving him erroneous ideas which will affect his later studies in analytical and physical chemistry. Some instructors take the extreme attitude that all first-year work should follow the historical order which the science developed of first qualitative and then quantitative study. The answer to this argument is best given by Smith and Hall (1): The history of modem chemistry begins with Priestley, Lavoisier, and Camdish, but it was the quantitative part of their work which alone really deserved the designation fundamental. It is difficult to see why a pupil should he dragged through a foghank of alchemy and empiricism simply because the rest of the world lost its way and wandered in such a fog for hundreds of years.
Literature Cited ( I ) Smm and
HALL, "The Teaching of Chemistry and Physics in the Secondary School," Longmans, Green & Co., New York City, 1904, p. 121.
