8 BIOLOGY. [BOOK i. 



Let a third atom of carbon then unite itself to this molecule, 

 we have an octovalent molecule : 



I l I 



c c c 



Finally, the adjunction of a fourth atom of carbon gives a 

 decavalent compound : 



c c c c 



This notion of autosaturation has enabled us to systematise a 

 quantity of facts of organic chemistry, to create rationally new 

 compounds, to classify and to seriate groups. We ow T e to it the 

 theory of alcohols, and that of hydrocarburets. 1 



The preceding pages contain the principal notions of general 

 chemistry, which as we proceed we propose to apply. We must, 

 however, before ending this chapter say a few words on what 

 have been called catalyses. Certain bodies brought into contact 

 with other bodies determine by their presence alone, and without 

 taking any other part in the reactions, either combinations or 

 metamorphoses or unfoldings. It seems as if in these cases the 

 body, intervening, by its presence alone, brings into play an attrac- 

 tive force sufficient to disturb the atomicity of the body which it 

 influences, without, however, being able to enter into combination 

 with that body. For instance, platina determines, by its presence 

 alone, the combination of oxygen and hydrogen, the formation 

 of water; it transforms also alcohol into acetic acid by deter- 

 mining its oxidation. 



These are catalyses of combination. 



The albuminoidal substances introduced into the stomach 

 impregnate themselves there with gastric juice, expand, and in 



1 Consult for further details, Wurtz, Philosophie Chimique, Chimie nouvdlc, 

 etc. Haquet, article, Atomique (Theorie) in the Encyclopedic Generate. 



