80 HARRY C. JONES 



problems of gases may today be said to be solved. We know the 

 laws of gas pressure. We know the molecular weights of sub- 

 stances in the gaseous state, and this is fundamental to the deter- 

 mination of the atomic weights of the various chemical atoms. 

 We know a good deal about the inner mechanism of gases when 

 conducting heat, light and electricity, due especially to the 

 recent beautiful investigations of Sir J. J. Thomson. We can 

 deal with gases by thermodynamical methods and apply the first 

 and second principles of this, an exact mathematical science, to 

 them. All in all, we know infinitely more about matter in the 

 gaseous state than in the liquid and solid states both taken 

 together. 



We can now see why it is so important to be able to deal with 

 solutions as we can deal with gases. We are thus able to deal with 

 solutions to some extent by the rigid mathematical methods to 

 which gases conform. Since the discovery made by Van't Hoff 

 we really know something about matter in solution, but this raises 

 the further question why is it so important to deal with solutions 

 by the exact scientific method, or by any method whatsoever? 

 Why is a knowledge of solutions so fundamental not only for 

 chemistry, but for so many of the other branche^of natural science? 

 And this question brings us to the most important part of our 

 task. 



THE IMPORTANCE OF SOLUTIONS 



A moment's reflection will show the importance of solutions 

 for natural science in general. The term solution is used here 

 in the broadest aspect of the subject. We know matter in three 

 states of aggregation, solid, liquid and gas. A solution is a homo- 

 geneous mixture of matter in the given state of aggregation with 

 matter in the same or a different state of aggregation ; the compo- 

 nent parts of which cannot be separated mechanicall3^ In terms 

 of this definition we can have solid, liquid or gas acting as a 

 solvent, and every state of aggregation dissolved in its own or 

 in any other state of aggregation. We would, consequently, 

 have nine types of solution. 



Bearing in mind this broader definition of solution, the meaning 



