464 THE POPULAR SCIENCE MONTHLY. 



will be a block of ice. Nay, more ; when by such mechanical means 

 subdivision can be carried no further, we may resort to a gentle heat 

 and find these microscopic blocks crumbling into fragments finer still ; 

 for what is melting but a process of division ? In it, particles simply 

 fall apart because the ties of cohesion are sundered by the heat, and 

 the liquid is the same substance, differing from the impalpable powder 

 only in the mobility due to its finer state of division. Now touch the 

 liquid with a somewhat intenser heat. We find that the water is con- 

 verted into steam, becoming invisible, and that the water-gas occupies 

 a volume seventeen hundred times larger than did the water which it 

 represents. However remarkable this change, yet it does not touch 

 that which gives character to the substance. In all its essential prop- 

 erties it is water still. Furthermore, not the slightest addition or 

 subtraction has been made. The process, in all its ste})s, from the 

 original block of ice to the seventeen-hundred-fold volume of invisible 

 vapor, is simply a process of division. 



Now endeavor to carry the subdivision further. It may be that a 

 fiercer heat will be a keener edge to cleave the invisible particles of 

 water-gas. Thanks to Professor Chandler, who has taught us how to 

 apply the requisite heat without at the time introducing a chemical 

 attraction, so that we may be left confident that, whatever the result, 

 it is accomplished by the same agents by which our previous subdi- 

 visions have been made. 



In this experiment the steam is passed into a platinum flask, which 

 is kept red-hot. From this flask a delivery tube conveys it to a jar 

 designed to receive the products of the experiment. The invisible 

 steam enters the platinum flask ; an invisible gas also passes onward 

 to be caught in the receiver ; but afterward, on bringing a flame to 

 the mouth of this receiver, an explosion declares that its contents are 

 water-gas no longer that a mixture of hydrogen and oxygen has 

 taken its place. The steam particles are evidently broken by the heat. 

 But mark the result : the fragments are no longer particles of water. 

 The red heat has dissected the steam particles, and revealed the fact 

 that they consist of still smaller pieces of hydrogen and oxygen. 



In the form of steam, therefore, water is in its finest possible state 

 of division, for to divide it further is to compel it to cease to exist 

 as water. We are therefore entitled to declare that this substance 

 consists of ultimate particles, which can not be divided without chang- 

 ing them into other kinds of matter. These are its molecules. Next, 

 in the light of chemical synthesis, also, we may see the existence of 

 these ultimate particles. 



Hydrogen and oxygen are the inevitable constituents of water, 

 and two volumes of hydrogen to one volume of oxygen are the invari- 

 able proportions. No human agency can obtain water by combining 

 any other elements, nor by combining these in any other proportions. 



These are facts confirmed by all experience. Nevertheless, it mat- 



