62 THE BUTYRIC ACID GROUP. 



vice or in the chyle ; we know not what becomes of the other ele- 

 ments which are eliminated during the conversion of starch into 

 butyric acid ; and finally, chemically considered, butyric acid has 

 no greater claim to the name of a fatty acid, than acetic or formic 

 acid. We do not think that the conclusion can be justly deduced, 

 that starch must be converted into butyric acid in order to be 

 transformed into fat, simply because it accidentally happens that 

 butyric acid was first prepared from a (very rarely occurring) fat, 

 for we know that it may just as easily be obtained from albumi- 

 nous bodies, and in far larger quantities from gelatin. 



There is much stronger evidence in favour of the view which 

 regards the butyric acid found in the blood, sweat, and urine, as a 

 product of decomposition, arising from the disintegration of nitro- 

 genous animal matters, effected by the oxygen dissolved in 

 the juices, (in the same way as the acid is formed from these 

 substances by artificial means,) or as probably resulting from a 

 gradual oxidation of some of the carbo-hydrogens of the fats. This 

 latter view is, however, only an hypothesis ; but it is supported 

 by the simplest induction. The fats are almost all combinations 

 of fatty acids with a haloid base, glycerin or oxide of lipyl; these 

 acids are, however, so similarly constituted to those of this group, 

 that they have the same general formula=C n H n _ 1 O 3 . HO, with 

 only this difference, that the carbo-hydrogens pertaining to them 

 are expressed by higher atomic numbers (thus, for instance, mar- 

 garic acid=zC 34 H 33 O 3 .HO). In the complicated apparatus of 

 oxidation which we recognise in the animal organism, the fats do 

 not burn like the oil in the wick of a lamp, but they undergo an 

 extremely gradual oxidation, as we learn from direct experiments, 

 which have given us a knowledge of a very large number of fatty 

 acids, with the most varied polymeric carbo-hydrogens, or, if we 

 please so to express it, in the lowest stages of oxidation. From 

 experiments instituted on this group of acids, we may assume that 

 in the gradual oxidation, C 2 H 2 is always abstracted from the radical 

 of n.argaric acid, and that this gradual abstraction may proceed 

 with various degrees of rapidity, so that, in our investigations, we 

 meet with carbo-hydrogen compounds of a lower order, which then 

 progressively pass into the carbo-hydrogens of the acids of this group. 

 As the radical C 4 H 5 of ethyloxalic acid passes into methyloxalic 

 acid, we are justified in believing that the radical of margaric acid 

 passes into cetylic acid. A gradual decarbonisation of the fats 

 must occur in the animal organism ; and there are at present no 

 scientific reasons for assuming that it takes place in any other 

 way than that which has been described. We regard butyric acid, 



