Uhap. I. J CONSTITUTION OF MATTER. 



consequence tte organic substance of the gastric juice achiev( 

 in these alimentary substances an isomeric modification, whic 

 renders them liquid, absorbable, in short, transforms them ini 

 albuminose. In the same way, under the influence of sulphur 

 acid diluted, cane-sugar, cellulose, gums, and f ecules are metamo 

 phosed first of all into dextrine, and then into glycose, or grap 

 sugar. 



These are isomeric catalyses. 



The hippuric acid of the urines of herbivorous anima 

 unfolds itself, under the influence of the mucous elemen 

 modified by the air, into hippuric acid and sugar of gelatine i 

 glycocoU. 



That is an unfolded catalysis. 



In sum, the universe must be regarded as a whole composi 

 of atoms dissijnilar, and variously grouped according to the 

 affinities. These active atoms are the foundation, the substanc 

 the cause of all things : to use the expression of Tyndall, thi 

 are giants travestied. 



The various aspects of bodies result from the various mod 

 of aggregation of the constituent elements. 



" All the changes accomplished on the surface of the globe a 

 due to combinations which are made or -to combinations whi( 

 are unmade." ^ 



All chemical phenomena are consequently the expression 

 atomic combinations, and can be included in four gener 

 types: 



1. Simple change of molecular structure, or isomeria. 



2. Unfolding of compound molecules. 



3. Adjunction, addition of atoms, or of molecules not y 

 saturated, or, inversely, subtraction of atoms. 



4. Substitution of certain atoms, certain molecules for othe 

 in a compound body. 



These general characteristics manifestly exclude all lil 

 mate, all radical difference between living organised bodies ai 



1 Dumas, Traiti de Chimie, t. viii. 



