SOME CONSEQUENCES OF GRAHAM'S WORK 609 



movement and that of invisible dissolved molecules, besides 

 simple kinetic forces there are not also oscillatory forces at work 

 which have their origin in chemical changes within the liquid. 



It is impossible to think of the dissolution of a solid substance 

 by water as a merely mechanical process in which a solid mass 

 is resolved into its constituent molecules and these are distributed 

 among the water molecules. Dissolution, as Graham indeed 

 implies, must be regarded as conditioned by the existence of a 

 definite affinity between the dissolved substance and the solution 

 and as maintained, when once effected, in virtue of the continued 

 operation of such affinity. 



Unfortunately, having once learnt to regard water as a 

 compound of the two elements hydrogen and oxygen and to 

 represent its molecular composition by the simple formula H 2 0, 

 chemists have insensibly come to regard water as a simple 

 substance. The habit of speaking of water as existing in three 

 different physical states has so grown upon us, that we have 

 failed to recognise that it is different physically in its three states 

 because these differ chemically. If a chemical change be defined 

 as any alteration in molecular composition or configuration, 

 most cases of so-called physical change, in my opinion, are cases 

 of chemical change. I submit that we are as much obliged to 

 regard the passage of water from solid to liquid or from liquid 

 to gas as a case of chemical change as we are that of red to 

 yellow phosphorus — to suppose, that is to say, that the 

 changes of state are either depolymerisation or polymerisation 

 phenomena. 



I have proposed the name Hydrone for water in its simplest 

 molecular form — that of steam, to which alone the formula H 2 

 is applicable. Liquid water may be supposed to be a mixture of 

 various " polyhydrones " with more or less hydrone, the amount 

 of this latter being greater the higher the temperature. 1 



We have no means of determining the composition of the 

 polyhydrones present in water and ice; we can only consider 

 possibilities and probabilities. The argument from analogy 

 justifies us in believing that a series of complex molecules may 

 exist. On the present occasion I will merely call attention to 

 the following formulae representing compounds of the hydrone 

 molecule which are conceivably present in water : 



1 The subject is more fully discussed in articles published in SCIENCE PROGRESS 

 in January and April 1909. 



