THE CHEMISTRY OF THE ANIMAL BODY. 537 



probability that acetone is derived from fat renders it possible that these aeids 

 may also be derived from fat, and not from abnormal proteid decomposition, 

 as was formerly supposed. 



Acetic acid is the product of the oxidation of alcohol. This may be 

 brought about through the presence of spongy platinum, or through the action 

 of bacteria (Mycoderma aceti) on dilute alcohol (preparation of vinegar, sour- 

 ing of wine : for reaction see p. 532). Acetic acid, as well as other higher fatty 

 acids, is one of the products derived from proteid through its putrefaction, its dry 

 distillation, its fusion with potash, and its digestion with baryta water in sealed 

 tubes. Formic, acetic, and propionic acids are products of dry distillation of 

 sugar (formation of caramel). These facts are of importance in their rela- 

 tion to the question of the production of fat in the body. Acetic and the 

 higher fatty acids are, further, products of the dry distillation of wood and 

 of the fermentation of cellulose (see p. 532). Putrefaction of acetates may 

 take place in the intestines, the reaction being as follows : 



2CH 3 COONa + 2H 2 = Na 2 C0 3 + 2CH 4 + H 2 + C0 2 . 



These products are similar to those in the marsh-gas fermentation of cellulose. 

 Vinegar, whose acidity is due to acetic acid, is used as a condiment. 



Acetyl-acetic Acid, or Aceto-acetic Acid, CH 3 .CO.CH 2 .COOH. — This 

 may be considered as acetic acid in which one H atom is replaced by acetyl, 

 CH 3 CO — ; or as /9-keto-butyric acid. Treated with hydrogen it is reduced 

 to /2-oxybutyric acid (CH 3 .CHOH.CH 2 .COOH), which in turn may be oxi- 

 dized to the original substance. Aceto-acetic acid readily breaks up into acetone 

 and carbonic acid : 



CH 3 COCH 2 COOH = CH 3 COCH 3 + C0 2 . 



Aceto-acetic acid, acetone, and /3-oxybutyric acid are found in the urine sometimes singly, 

 sometimes together, and probably as the result of a metabolism of fat. In starvation and 

 in diabetes there is an increased excretion of these bodies, for there is an Increased metabo- 

 lism of fat. Feeding fat increases the acetonuria, whereas feeding sugar, which protects 

 the fat from destruction, decreases it. 1 From their chemical relations already mentioned 

 these substances may be regarded as of common origin, and in confirmation of this 

 Araki 2 has shown that on feeding /3-oxybutyric acid it is oxidized and aceto-acetic acid 

 and acetone may be detected in the urine. The production of the two aeids seems to 

 further a gradual neutralization of the blood, ultimately causing coma. 3 In the presence 

 of these substances ammonia runs high in the urine, and in amounts proportional to their 

 excretion * (compare p. 550). 



Aceto-acetic acid gives to urine in the absence of phosphates a red coloration 

 with ferric chloride (principle of the reaction of Gerhardt). 



Amido-acetic Acid, or Glycocoll, CH 2 .NH 2 .COOH, — This is a substance 

 obtained by boiling gelatin with acids or alkalies. It is found in human bile 

 and in that of other animals combined with cholic acid and called glycoeholie 

 acid. Chittenden'' has found glycocoll in the muscles of Peeten irradiam. 

 It is found in the urine combined with benzoic acid as hippuric acid after 



'Literature by Waldvogel : Zeitsehrift fur klinische Mediein, 1899, Bd. 38, S. r>06. 



2 Zeilschrift fiir physiologmhe Chemie, 1893, Bd. 18, S. 6. 



3 Miinzer and Strasser: Archiv fur exper, Pathologie und Pharmakologie, 1893, Bd. 32, S. 372. 

 * Loc. n't. 5 An»ii/rii der Chemie und Pharmakologie, 1875, Bd. 178, S. 266. 



