ORGANIC PEmCIPLES. 73 



ciples, out of the body, is putrefaction. In contact with 

 the air, at a moderate temperature, they undergo decompo- 

 sition into carbonic, lactic, and butyric acids, and ammonia. 

 When this change has once commenced, it has been found 

 by "Wurtz to continue in a vacuum. 1 Putrefaction is a 

 process peculiar to organic substances. By it they are 

 transformed into substances which are used in the nutrition 

 of vegetables ; and as vegetables are eventually consumed by 

 animals, the animal matter is not lost, but returns again 

 through this channel, so that the two kingdoms are continu- 

 ally interchanging elements. Organic matters in putrefac- 

 tion are capable of setting up the same process in other 

 articles of this class by simple contact, neither giving up nor 

 taking away any chemical elements. They are then called 

 ferments, and this action is said to be catalytic. As before 

 remarked, this constitutes one of the most important charac- 

 teristics of organic matters ; one, indeed, which enables us 

 to recognize them when they exist in quantities too minute for 

 chemical analysis, as in exhalations from the pulmonary and 

 cutaneous surfaces. 



Proteine. In 1838, just after the promulgation of the 

 theory of vegetable organic radicals by Liebig and Dumas, 

 Mulder attempted to show that the organic animal substan- 

 ces were all compounds of a radical which he called Prote- 

 ine. This theory was pretty generally received, and gave to 

 organic matters the name of Proteine Compounds, by which 

 they are sometimes known. He treated albumen, fibrin, and 

 caseine with alcohol and ether to remove the fats, and with 

 hydrochloric acid to remove inorganic salts ; dissolved them, 

 thus purified, in a solution of potash, and precipitated with 

 acetic acid a substance said to possess always the same char- 

 acters, which he called proteine ; and which, by union with a 

 certain quantity of sulphur and phosphorus, w^as capable 

 of forming fibrin, albumen, and caseine. But the analyses 



1 Cited by ROBIN and VERDEIL, op. cit., tome in., p. 142. 



