xviii THE ELEMENTS AND LIFE 365 



" It would seem that carbon has properties which are altogether 

 special ; the influence which it exerts upon other elements in 

 depriving them of their activity is so remarkable." 



We see, therefore, that carbon is perhaps the most unique, 

 in its physical and chemical properties, of the whole series 

 of the elements, and so far as the evidence points, it seems 

 to exist for the one purpose of rendering the development of 

 organised life a possibility. It further appears that its 

 unique chemical properties, in combination with those of 

 the other elements which constitute protoplasm, have enabled 

 the various forms of life to produce that almost infinite 

 variety of substances adapted for man's use and enjoyment, 

 and especially to serve the purposes of his ever-advancing 

 research into the secrets of the universe. 



Water : its Relations to Life and to Man 



The compound water is as essential for building up 

 living organisms as is carbon, and it exhibits peculiarities 

 almost as striking as those of that element. Its more 

 obvious qualities are singularly unlike those of its com- 

 ponents, oxygen and hydrogen : oxygen supports combustion, 

 water checks or destroys it ; hydrogen burns readily, water 

 is incombustible. Water is wonderfully stable at ordinary 

 temperatures, hence it is the most innocuous of fluids ; it is 

 also an almost universal solvent, hence its great value in 

 cookery, in the arts, and for cleansing purposes. Besides 

 being absolutely essential for vegetable and animal life it has 

 qualities which render it serviceable to civilised man, both 

 in his pleasures and his scientific discoveries. Absolutely 

 pure water is a non-conductor of electricity ; but as all 

 natural waters contain gases or salts in solution, it then 

 becomes a conductor, and is partly decomposed, or becomes 

 an electrolyte. The various curious facts connected with 

 water are so puzzling, that in April 1910 the Faraday Society 

 held a general discussion in order to arrive at some solution 

 of what is termed in the Electrical Review " the most 

 complex of problems." One of the facts that seem to be 

 now generally accepted is, that water is not the simple 

 compound, H 2 0, it is usually held to be, but is really a 

 compound of three hydrols, H 2 being gaseous water, 



