July 31, 1896.] 



SCIENCE. 



133 



have no conception. They are chemically 

 helpless if they cannot have pencil and 

 paper and are not allowed to express them- 

 selves in the form of chemical equations. 

 It must be confessed that the teachers are 

 more responsible for this state of affairs 

 than the pupils, because in many text-books 

 and laboratory manuals we find, possibly 

 for the sake of a mistaken idea of saving 

 printer's ink and paper, directions, para- 

 graph and chapter headings given in the 

 shape of chemical formulae to a beginner in 

 the science. The current language was 

 constructed for chemists as well as for other 

 mortals, and I see no reason why we should 

 not express ourselves in its terms. The 

 pupil should be able to tell us what he 

 knows, and he should not be wedded to his 

 writing materials. 



One phase of chemical investigation has 

 made such enormous strides of late years 

 that it can no longer be ignored even by 

 beginners in the science. I refer to so- 

 called physical chemistry. From the start 

 the teacher and pupil must recognize that 

 there are two enduring things in the uni- 

 verse — matter and energy— and that but 

 half of the tale has been told, when in study- 

 ing a chemical change, only the former has 

 been considered. Of course, it is not possi- 

 ble in all cases to consider the latter; none 

 of us are as yet able to do that, no matter 

 how great our experience or how much we 

 have worked in this line ; but in the simple 

 reactions which are encountered at the be- 

 ginning of the course the question of energy 

 changes can be dwelt upon as clearly as the 

 others. Such a line of work requires a cer- 

 tain knowledge of physics, and " as chemis- 

 try is a branch of the study of the relations 

 of matter and energy it should be preceded 

 by the more general aspect of this subject 

 which is undertaken by physics. Obviously, 

 owing to the close connection between chem- 

 istry and physics it will frequently be re- 

 quired to more clearly outline physical topics 



in chemical work, and to enable the teacher 

 to make such outlines, a preliminary gen- 

 eral knowledge of physics is necessary."* 

 Another topic in physics which must neces- 

 sarily be introduced before the atomic hy- 

 pothesis is taken up, is the kinetic gas theory, 

 for a comprehension of which some knowl- 

 edge of elementary energetics is necessary. 

 It is very easy to make the pupil learn the 

 dogmatic statement that ' in equal volumes 

 of gases, under like conditions of tempera- 

 ture and pressure, there are equal numbers 

 of molecules,' but to make him understand 

 why this fundamental theory is accepted 

 by the scientific world, and what is its 

 bearing on our present system of atomic 

 weights, requires careful reasoning and con- 

 scientious teaching, without which the 

 dogma becomes as useless as any other em- 

 pirical utterance. In short, I would have 

 the pupil's preliminary work, both physical 

 and chemical, so centered around observed 

 facts that he will approach his theoretical 

 conclusions with a mind free from bias, and 

 so logically trained in the successive steps 

 that he may enter upon his more difiicult 

 task in a condition to comprehend its full 

 meaning and significance. It is desirable 

 that he should feel the need of some such 

 theory as the atomic theory, before the 

 teacher shows him the way for its develop- 

 ment. 



Double decomposition and phenomena 

 attendant upon it have lately come to be 

 among the most important topics in physi- 

 cal chemistry. This subject must be intro- 

 duced in an elementary course, but the 

 present state of the science forbids that it 

 shall be treated from an empirical stand- 

 point in which the most important fact is 

 the obtaining of a precipitate which can be 

 made to serve the purpose of identifying 



^Extract from a report made by a committee con- 

 sisting of Messrs. Noyes, A. Smith and Freer at the 

 conference of chemists of the Northwest at Chicago, 

 January 2, 1896. 



