CHAPTER XVIII 



THE ELEMENTS AND WATER, IN RELATION TO THE LIFE-WORLD 



I HAVE already (in Chapter XVI.) given the statements of 

 two continental physiologists as to great chemical complexity 

 of the proteid molecule, involving as it does, in certain cases 

 already studied, a combination of about two thousand chemical 

 atoms. A more recent authority (Mr. W. Bate Hardy) is of 

 opinion that this molecule really contains about thirty thou- 

 sand atoms, while the most complex molecule known to the 

 organic chemist is said to contain less than a hundred. One 

 of the results of this extreme complexity is that almost all the 

 products of the vegetable and animal kingdoms are what are 

 termed hydro-carbons, that is, they consist of compounds of 

 carbon, with hydrogen, oxygen, or nitrogen, or any or all of 

 them, combined in an almost infinite variety of ways. Yet 

 the compounds of these four elements already known are more 

 numerous than those produced by all the other elements, more 

 than seventy in number. 



This abundance is largely due to the fact that the very same 

 combination of carbon with the three gaseous constituents of 

 the carbon-compounds often produces several substances very 

 different in appearance and properties. Thus dextrine (or 

 British gum), starch, and cellulose (the constituents of the 

 fibres of plants) all consist of six atoms of carbon, ton of 

 hydrogen, and five of oxygen ; yet they have very different 

 properties, cellulose being insoluble in water, alcohol, or ether ; 

 dextrine soluble in water but not in alcohol ; while starch is only 

 soluble in Avarm water. These differences are supposed to be 

 due to the different arrangement of the atoms, and to their being 

 combined and recombinod in dift'orent ways; and as the more 

 atoms are used, the possible complexity of these arrangements 



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