CHAPTER I. 

 THE PROPERTIES OF SOLUTIONS. 



A. Colloids and Crystalloids. 



The condition of a substance in " solution " is one that 

 differs considerably with different substances ; moreover, it 

 may differ with the same substance, depending on the 

 method of preparing the solution. All "solutions" can 

 be regarded as suspensions of particles in the "solvent." 

 The size and nature of the particles cause variations in 

 the physical properties of the solution. 



There are four classes of so-called "solutions," which are 

 not, however, very sharply differentiated from one another. 

 They are 



(ELECTROLYTES. 

 \NON-ELECTROL YTES. 



COLLOIDS 



(SUSPENSOIDS. 



Probably the essential difference between colloids and 

 crystalloids is the size of the particles suspended in the 

 fluid. In the crystalloids these particles are small, con- 

 sisting of ions or single, relatively small molecules. In the 

 colloids the particles are large, either because the molecules 

 themselves are large, or because they tend to aggregate 

 and form relatively large masses. The difference 

 between emulsoids and suspensoids is probably that 

 suspensoids are two phase liquids in which the " solvent " 

 (external phase) does not combine with the " solute " 

 (internal phase), that is to say, the solute is in real 

 suspension in the so-called solvent. In emulsoids, on the 



