Oct. 6, 1887] 



NATURE 



537 



I 



ments on these occurrences, it classifies and generalizes, 

 and tries to ascend from empirical generalizations to 

 natural laws. The business of the teacher of chemistry 

 I take to be to make his pupil understand the methods of 

 chemistry ; to select typical facts and put these before the 

 learner so that he may to some extent see their relative 

 importance in the general scheme of well-built knowledge ; 

 to show the student how complex are the phenomena 

 chemistry investigates, and how she simplifies that she 

 may explain ; to imbue him with some of that fine enthu- 

 siasm without which no great work is possible, by pre- 

 senting to him glimpses of the greatness of the subject he 

 is studying, and the importance of the prosecution of the 

 study ; and thus to build up in the student a scientific 

 spirit, until at last the teacher and the learner are merged 

 in their common investigation of nature. 



In teaching chemistry the all-important things appear 

 to me to be chiefly four : (i) to teach so that the student 

 shall acquire real knowledge ; (2) to carefully select both 

 the facts and the reasoning to be set before the student ; 



(3) to impress the learner with the importance and value 

 of what he is learning as a part of that orderly and 

 methodized study of nature which we call science ; 



(4) to teach without fear of the examiner. 



Real knowledge of chemistry can only be acquired by 

 connecting the experimental work in the laboratory with 

 chemical reasoning and with the principles of the science. 

 This is rarely done in our chemical schools. The student 

 generally hears lectures on chemistry, or at least on the 

 materials from which chemical science is constructed ; he 

 sees experiments performed that have some connexion 

 with what the lecturer teaches ; then he goes into the 

 laboratory and day after day performs qualitative analyses, 

 for the most part by rule of thumb. The learner, espe- 

 cially the beginner, cannot connect what he is taught in 

 lectures, and told to read in books, with what he does in 

 the laboratory. The introduction of a well-arranged and 

 properly graduated system of practical chemistry, is, in 

 my opinion, one of the things which will do much to 

 hasten the advance of chemistry among us. The work 

 done in the laboratory must be directly connected with 

 the lecture-work and the reading of the student ; it must 

 be progressive, beginning with easy experiments and lead- 

 ing the student onwards until he is al)le to investigate 

 chemical occurrences for himself; and it must be arranged 

 so that as the experimental work becomes more difficult 

 the reasoning on the results becomes more close and 

 accurate. 



Such a course of practical chemistry can be arranged 

 without any complicated laboratory appliances. (I may 

 say parenthetically that in my opinion the building of 

 luxuriously fitted laboratories has not been an unmixed 

 gain to chemical science.) 



In the course of laboratory work which seems to me to 

 be called for, the student would begin with easy experi- 

 ments on chemical and physical change, on the distinction 

 between elements and not-elements (this would involve 

 quantitative measurements), and on the classification of 

 not-elements into mixtures and compounds. He would 

 then proceed to classify compounds into acids, bases, and 

 salts, working through well-chosen examples of each 

 class. He would learn by his own experiments what is 

 meant by " the replaceable hydrogen of acids," and by 

 the classification of acids in accordance with their 

 " basicity." He would study classes of elements, and so 

 get a real grasp of the reasons for placing certain ele- 

 ments in one class, and of the principles of chemical 

 classification. After hearing in the lecture-room about 

 the properties of the members of a class of elements— say 

 the iron class— he would at once go into the laboratory 

 and himself prepare typical similar compounds of these 

 elements. He would then turn to the conditions of 

 chemical action ; he would practically learn what an 

 ordinary chemical equation teaches, and he would be im- 



pressed, by the results of his own experiments, with the 

 importance of determining the conditions under which 

 chemical changes occur, and with the many and varied 

 facts regarding even every-day chemical changes which 

 are not expressed in our chemical notation. The study 

 of the conditions of chemical change would lead on 

 to the study of affinity, of dissociation, and of allied 

 subjects. 



Turning again to the study of composition, the student 

 would make determinations of the equivalent weights of 

 a series of similar compounds, and also of several ele- 

 ments ; he would determine the molecular weights of a 

 few gaseous bodies, and the atomic weights of one or two 

 elements. He would then proceed to study experimentally 

 some of the methods whereby light is thrown on the con- 

 stitutions of compounds. For instance, he would deter- 

 mine the specific volumes of a series of carbon compounds, 

 the rates of etherification of a series of alcohols, and the 

 nature of the products of the reaction of such a compound 

 as phosphorus pentachloride with carbon compounds 

 belonging to different classes but showing similarities of 

 composition. Thus the molecular and atomic theory 

 would become a reality to him. Finally, he would be 

 required to repeat an investigation before undertaking 

 himself to advance into tlTe realm of the unknown. 



In such a course as this the student would study a series 

 of carefully selected facts ; his reading and laboratory 

 work would go hand in hand, each would react upon the 

 other, and so he would be saved from the danger of 

 attempting to draw a distinction between two things 

 which are truly one — chemistry and chemical philosophy. 



In selecting the facts and reasoning to be placed before 

 the student of chemistry I think we should now finally 

 abandon the method of treating the elements individually, 

 and rather consider them in groups or classes. If this is 

 done the student soon acquires a fair knowledge of 

 chemical facts ; he learns the compositions and properties 

 of groups of similar compounds, he traces some of the 

 connexions between changes of composition and of pro- 

 perties in analogous compounds. By considering the 

 elements in groups the artificial difference between rare 

 and common elements disappears, and this, I think, is a 

 decided gain. The learner also begins to recognize that 

 there are reasons for classing certain elements and com- 

 pounds together ; he sees that order and law pervade 

 the vast domain of chemistry ; he connects the constant 

 atomic weight with the position of each element in the 

 scheme of classification ; and so he gains a basis on which 

 he may rest the superstructure of facts as they are pre- 

 sented to him. This method of treatment inspires the 

 learner with the hope that it is possible to get a firm hold 

 of the subject he is studying. The method is progressive : 

 principles are seen to arise out of the classes of facts 

 considered ; each event examined appears as at once the 

 cause and the consequence of other events ; generalizing 

 on facts accompanies the acquisition of the facts them- 

 selves. 



But if the student is expected to learn the pro- 

 perties of each element and its compounds, proceeding 

 from element to element, he generally completely fails to 

 grasp the connexion between similar elements ; indeed, 

 he usually and not unnaturally inquires why he should 

 be burdened by these details, which seem to him onlyun- 

 nieaning facts : if he knows and can repeat the proper- 

 ties of half-a-dozen elements, what the better is he for 

 knowing and being able to repeat the properties of a 

 dozen more .? The additional facts do not seem to help 

 him to a knowledge of chemistry. And so he either 

 despairs of finding any guiding light in the maze of facts, 

 or he falls into the error of supposing that the maze in 

 which he is wandering without a clue is chemistry. It is 

 the old school method again, which teaches the useless- 

 ness of knowledge. When we look back on our school 

 days do we not regret the hours wasted on learning rules 



