32 THE MECHANISM OF LIFE 



tion of pure water is but small. Water is, however, the most 

 important of all the various agents in the chemical reactions 

 of life, since a large number of organic substances are de- 

 composed by water by a process of hydrolysis, and a vast 

 number of organic substances are but combinations of carbon 



with the ions II and OH, their diversity being due to variations 

 in the relative proportions and grouping. 



The Chemical, Therapeutic, and Toxic Actions of Ions. — The 

 chemical, therapeutic, antiseptic, and toxic actions of electro- 

 lvtic solutions are almost exclusively due to ionization. Take, 

 for instance, a solution of nitrate of silver in which the addition 

 of chlorine produces a white precipitate of chloride of silver. 

 This precipitate occurs only when the solution added is one 



such as NaCl, where the chlorine is present as the free ion C'l. 

 No such precipitate is produced in a solution of chlorate of 

 potassium or chloracetic acid, where the chlorine is entangled 

 in the complex ion C10 3 or C 2 H 3 C10 2 . 



Since, then, the toxic and pharmacological properties of an 

 electrolvte depend entirely on the ionic grouping, it behoves 

 the physician and the biologist to study the structure and 

 grouping of the ions in a molecule, rather than that of the 

 atoms. Consider for a moment the totally different properties 

 of the phosphides and the phosphates. The former are ex- 

 tremely toxic, while the latter are perfectly harmless. There 

 is not the slightest analogy between their actions on the 

 living organism. On the other hand, all the phosphides pro- 

 duce the same toxic and therapeutic effects, whatever the 

 cation with which they are united. Their toxic properties 



ai - e derived from the presence of the free phosphorus ion P. 

 The phosphates contain phosphorus in the same proportion 

 as the phosphides, but this phosphorus is harmlessly entangled 



in the complex ion P0 4 , whose properties are absolutely 



different from those of the ion P. 



The above considerations apply equally to the chlorides 

 and chlorates, the iodides and iodates, the sulphides and 

 sulphates, and in general to all chemical salts. 



