June 2, 1892] 



NATURE 



99 



" can hardly be other than those which so effectually 

 describe the relations of organic to organic and of organic 

 to inorganic phenomena in the earlier phases of their 

 development." A curious assertion, surely, for one to 

 make who objects to Newton's laws of motion because 

 they don't include imaginable but still unknown types 

 of corpuscular motion. The particular value, however, 

 of this confession of faith is that it enables the confessor 

 to convict of scientific heresy Prof. Robertson Smith 

 and all others who cannot regard it as other than an as- 

 sumption. To believe as Prof. Pearson believes is to 

 believe scientifically ; all other belief is rotten. As the 

 " auld licht " dame said when telling over the number of 

 the elect, "Ay, there's jist me and John ; and whiles I'm 

 no that sure o' John." C. G. K, 



THE TEACHING OF THE PRINCIPLES OF 

 CHEMISTRY. 



Laboratory Practice : A Series of Experiments on the 

 Fundamental Principles of Chemistry. A Companion 

 Volume to "The New Chemistry." By Josiah Parsons 

 Cooke, LL.D., Erving Professor, and Director of the 

 Chemical Laboratory, Harvard University. Pp. 192. 

 (London : Kegan Paul, Trench, Trubner, and Co., 

 1892.) 



THIS little book represents another attempt to teach 

 the theory of chemistry upon the basis of a narrowly 

 restricted experience of facts and phenomena. Whether 

 this is possible is a question debatable, and still, in fact, 

 debated among teachers. That it is possible to make 

 the study of chemistry by young people, as a form of in- 

 tellectual exercise, more useful than has usually been the 

 case there can be no doubt, and that much instruction 

 could be got out of a course such as this which is in- 

 dicated in Prof. Cooke's little work is certain. The 

 book appears to be intended as a guide for the teacher 

 as much as for the pupil, and much would depend upon 

 the qualifications of the former for the work of demon- 

 stration and exposition. It contains directions for the 

 performance of a system of experiments ; and to do 

 justice to the system the teacher ought carefully to study 

 the instructions given in the introduction, and to act upon 

 them. And to those who know anything of the manner 

 in which chemistry is too often taught in the schools of 

 this country, either by the visiting "science teacher," 

 who knows little, or by the mathematical master, who 

 usually knows nothing at all about the subject, such 

 remarks as the following, taken from the introduction, 

 will seem particularly welcome and appropriate. 

 The author says : 



" Experiments are only of value as parts of a course 

 of instruction logically followed out from beginning to 

 end. In such a course there must be necessarily a great 

 deal to be filled out by the teacher, and this can vastly 

 better be taught from his lips, with such illustrations as 

 he can command, than from any books." 



And again, 



"The best apparatus will be of no use unless the 

 teacher stands before it and speaks to his pupils out of 

 the fulness of his own knowledge. This is an essential 



condition of success, and without it the experimental 

 method should never be attempted." 



But after these things have all been duly noted and 

 acted upon, a glance at the table of contents is apt to 

 raise a doubt whether after all the erection of so large a 

 superstructure is justifiable or practicable upon founda- 

 tions so slender. The book begins at p. 13, and thence 

 to p. 52, with the exception of three or four pages about 

 water, the whole is devoted to the physical properties of 

 liquids and solids represented by water and air. Then 

 we come to oxygen, hydrogen, sulphur and its oxides, 

 chlorine, carbon and the oxides of carbon, ethylene, 

 nitrogen, nitric acid, ammonia, magnesium, zinc, sodium, 

 copper, and iron, all of which are included in the fifty 

 pages following. Then comes a chapter on general prin- 

 ciples, a third on molecules and atoms, followed by 

 chapters on symbols and nomenclature, molecular struc- 

 ture, and thermal relations. 



This is not the first book which has appeared with 

 similar objects. In this country there have been Prof. 

 Ramsay's little book on " Chemical Theory," Muir and 

 Carnegie's " Practical Chemistry," Shenstone's " Practical 

 Introduction to Chemistry," and probably others, which 

 seem to aim at dealing with chemistry in the same kind 

 of way, which is intended to be a way of pleasantness 

 and a short cut to rather exalted territory. The road, 

 however, is bordered by precipices unseen by the young 

 traveller. 



The advocates of this kind of system, which consists 

 in passing from one or two rough experiments, or obser- 

 vations, direct to great generalizations, anticipate great 

 things from its general adoption. All the rising generation 

 who come under its influence are to possess greatly de- 

 veloped powers of observation and reasoning. Some of 

 those who have been accustomed to old-fashioned ways 

 of getting a good grip of facts, and some stock of ex- 

 perience before proceeding to difficult investigation, are 

 not convinced, and are inclined to doubt whether school 

 boys and girls can be made to reason out for themselves 

 problems which have cost for their elucidation the work of 

 generations of men. And the logic of the process is 

 often more than questionable. Here is an example (p. 1 10). 

 The law of the conservation of mass is supposed to be 

 established by a single experiment, which consists in 

 burning a bit of phosphorus in a jar, and showing that 

 there is no loss of weight. 



" Hence it must be that. The sum of the weights of the 

 products of a chemical change is exactly equal to the sum 

 of the weights of the factors. We may conceive of any 

 chemical process as taking place in an hermetically 

 sealed space — indeed the earth is essentially such a space 

 — and hence this law must be universally true." 



Here the process of induction is reduced to collecting 

 a single instance, which is itself imperfect. Surely this is 

 not to stand as an example of the methods of physical 

 science. 



One would not wish to be hard upon Prof. Cooke's 

 little book, but with many meritorious features it does 

 not seem to represent a great improvement upon the 

 books referred to above. The naive statement at the end 

 of the introduction, that the directions can in many cases 

 be improved, cannot be held to excuse the rough and 



NO. 1 1 79, VOL. 46] 



