330 Repokt 8. a. a. Advancement of Science. 



were to rest on the mere ground of logical continuity, the sequence 

 " properties of matter, heat, chemical change, electricity " would be 

 preferable to "properties of matter, heat, electricit}' and chemical 

 change," and if on account of the extent of the subject some branch 

 has to be omitted, it would be better to omit electricity rather than 

 the elements of chemistry. 



There are, however, more important considerations which point 

 the same way. In the first place, the study of some chemistry gi-eatly 

 helps the teaching of physics from the psychological point of view and 

 vice versa. There is something elusive in man}'^ of the notions of 

 physics, such as force, quantity of heat, temperature, energy, etc., and 

 it is a great help to a young student, and also a decided stimulus, to 

 have his attention directed not merely to these ideas, but to the 

 material substratum to which they belong and to the changes in it 

 with which they are associated. Quantity of heat is a vague thing to 

 the oi-dinary school-boy, but the quantity of heat given out in the 

 burning of an ordinary candle weighing six to the pound is fairly 

 definite, and can be the subject of a quite performable experiment ; 

 nor does the subject lose its interest when he realises that the heat 

 evolved in this case is practically the cause of the explosion so dear to 

 his heart, when he applies a match to a mixture of h3'drogen and 

 oxygen. The fact that chemical change is so often in every-day life 

 the source of the energy whose transformation is the subject of physics 

 is a matter of great importance in its bearing on the teaching of 

 physics. Again, many foims of matter that are referred to in the 

 elementary laws of physics are unfamiliar to the boy who knows 

 nothing of chemistry. To ^ay that all gases expand equally when 

 raised at constant pressure from the freezing to the boiling point of 

 water conveys little to a student who knows only one gas — air — to 

 whom hydrogen, oxygen, carbonic acid gas, nitrogen are meaningless ; 

 and if we proceed on sound educational lines, and ask the student of 

 pure physics to find this law out for himself or even to verify it, how 

 is it to be done? If physics gains in definiteness of idea b}' being- 

 correlated with chemistry, chemistry gains enormously, especially in 

 systematic development, by being taught along with the elements of 

 physics. In fact, no chemistry course professes to be possible with- 

 out an introduction dealing with the simpler properties of matter and 

 with heat ; so that I need not labour the point further. 



The next point is that the proposed course follows more closely 

 the line of natural and historical discovery and development, and 

 lends itself more readily to an interesting training in the remaking of 

 discoveries. The ffict is that in some parts of physics, and especially 

 in experiments on heat, it is a little difficult to confine oneself to purely 

 physical changes, and the usual procedure in the physical laboratory is 

 highly artificial. Take such a case as the efiect of heat on a solid. 

 As one looks around theie is hardly anything within reach in which 

 the most obvious change pioduced by heat would not be a chemical 

 one. And in accordance with this is the fact that the subjects in their 

 earl}' stages, such as the days of the founding of the Royal Society 



