54 president's address — section b. 



universe, at least of that which appeals to our senses, as con- 

 sisting of what we arbitrarily call matter, and of its smallest 

 portion as the indivisible atom — an idea held by ancient 

 philosophers some three centuries before Christ ; the smallest 

 quantity assumed to exist freely in space under known con- 

 ditions being the molecule. From what we have seen and 

 fi'om all we know of infinitely minute particles of matter, can 

 we think or conceive that these molecules are huddled to- 

 gether like a chaotic heap of bricks? Assuredly not, — at 

 least not in a definite compound ; and the truth is borne in 

 upon us at the thought of the microscopic yet symmetrical 

 crystal. Looking about for a familiar and universally known 

 substance, we have in water an instance of a symmetrical 

 molecular system, whether under the form of solid ice, liquid 

 water, or gaseous steam, made up of three atoms. 



It will greatly assist us in our contemplation of the mole- 

 cule if for the nonce we magnify these atoms several million 

 times beyond their actual size. We should probably see a 

 small sphere rotating about an axis, and at a given distance 

 two larger spheres also rotating about their own axes, but 

 travelling in a definite orbit around the smaller sphere, the 

 three together forming a system revolving in one plane with 

 its own individual precession, the whole system capable of 

 moving at a great velocity in any possible direction. 



Calling these individual planets in the molecule by their 

 received names, we see oxygen as a central sun with two 

 large primary planets both called hydrogen, situate at equal 

 angular distances fi'om each other, but with nothing known 

 at present to distinguish either of the hydrogen planets from 

 each other. 



Suppose, now, their orbital velocity be caused to diminish 

 by friction and to finally cease, we should have each hydrogen 

 planet distant 180° from one another. Placing three such 

 systems with no orbital motion over each other so that the 

 hydrogen satellites shall be equi-distant, a straight fine 

 passing through and intersecting each of the centres of the 

 oxygen spheres will form a hexagon. 



Now, it is a fact that water in crystalhzing to snow and ice 

 assumes the form of the hexagon. May not this cessation 

 of the orbital motion determine the act of crystallization, and 

 on the other hand the widening and opening out of the 

 orbit determine the expansion, while the friction of hydrogen 

 against hydrogen satellite determines the heat caused by 

 compression. 



