586 THE POPULAR SCIENCE MONTHLY. 



There is, however, a danger with all laboratory manuals, which 

 must be sedulously avoided, and the danger is generally greater the 

 more precise the descriptions. They are apt to induce mechanical 

 habits which are fatal to the true spiiit of laboratory teaching. Not 

 long ago I asked a student, who was working in our elementary labo- 

 ratory, what he was doing. He answered that he was doing No. 24, 

 and immediately went for his book to see what No. 24 was. 1 fear 

 that a great deal of laboratory work is done in a way which this anec- 

 dote illustrates, and, if so, it is a mere waste of time. 



When teaching qualitative analysis it was always with me a con- 

 stant struggle to prevent just such a result, and many of the excellent 

 tables which have been prepared to facilitate analysis simply encour- 

 age the evil practice. It is an error to which college students, with 

 their exclusively literary preparation, are especially liable, and I have 

 no question that the proper conduct of our laboratories would be 

 made mucl; easier if the students came with a previous scientific 

 training. 



Thus far I have dealt solely with generalities, and my object has 

 been not so much to give definite directions as to make suggestions 

 which might lead to better systems of teaching. The details of these 

 systems may vary widely, and yet all may lead to the desired result if 

 only the true spirit of scientific teaching is preserved, and a teacher's 

 own system is generally the best system for him. This leads me to 

 exj)lain my own system of teaching chemistry — which presents some 

 novelties that may be of interest, and, although it has been worked out 

 in detail in the revised edition of the " New Chemistry," just published, 

 still a few words of explanation may be of value at this time in setting 

 forth its salient points. 



Chemistry has been usually defined as the science which treats of 

 the composition of bodies, and in most text-books the aim has been to 

 develop the scheme of the chemical elements, and to show that, by 

 combining these elements, all natural and artificial substances may be 

 prej)ared. In the larger text-books, which aim to cover the whole 

 ground and to describe all known substances, such a method is both 

 natural and necessary. But, as an educational system, this mode of 

 presenting the subject is, as a rule, profitless and uninteresting. The 

 student becomes lost amid details which he can only very imperfectly 

 grasp, and the great principles of the science, as well as their relations 

 to cognate departments of knowledge, are lost sight of. Moreover, 

 the system is unphilosophical, because it jiresents the conclusions of 

 chemistry before the observations on which they are based. Any 

 one who has attempted to teach chemistry from the ordinary element- 

 ary text-books must have experienced the truth of what I have said. 



A student learns a lesson about sodium and the various salts of this 

 metal, and, after glibly reciting the words of the text-book, how much 

 more does he know of the real relations of these bodies than he did 



