510 Dr. Redtenbacher on a Class of Organic Acids. 



and cenanthylic acids. Before I make any further observa- 

 tions in connection with these acids, I will refer to a non-vo- 

 latile body, which is also obtained by the oxidation of the 

 oily acids, and which appears as a middle member that first 

 originates from oily acids and then changes, on the one hand, 

 into suberic and pimelic acids, and, on the other, by the 

 presence of water into the volatile fatty acids. If the oxida- 

 tion is not carried so far that the last trace of the fatty stra- 

 tum in the retort does not disappear, there floats on the sur- 

 face of the water on cooling an oily stratum of an unguent 

 consistency, which, after washing with water, possesses a 

 strong odour of sweat. This unctuous body is heavier than 

 water, easily soluble in alcohol and aether, but not capable of 

 being distilled over. If heated to above 100° C, a kind of 

 combustion takes place of its elements, giving out an odour 

 of cinnamon and nitrous acid ; volatile fatty acids distil over, 

 and the remainder becomes quite black and tough ; suberic 

 acid may be detected in it ; when acted upon by an alkali it 

 is dissolved with a blood-red colour, and can be again sepa- 

 rated unchanged by an acid. When boiled with water in a 

 retort it undergoes decomposition, and volatile fatty acids 

 distil over into the receiver ; suberic and pimelic acid re- 

 main dissolved in the water in the retort, and the first acid 

 may be crystallized out. These bodies therefore appear to 

 consist of that portion of the atom of the oily acids combined 

 with nitrous acid which produce suberic and pimelic acids, 

 (CH) w 4 . 



As it was not possible to obtain it free from mixture, I did 

 not submit it to any further examination. The common ori- 

 gin of the volatile fatty acids from the oily acids clearly ac- 

 counts for the wide-spread occurrence of these with the oily 

 acids in all fat. 



As before stated, I have for many years examined, partly 

 myself and partly by means of others, the volatile aeids con- 

 tained in animal fat, namely, the fat of fowls, of geese, snakes, 

 badgers, hares, particularly human fat, and several others, 

 and in every one, without exception, I have discovered small 

 portions of volatile fatty acids. The most common appear 

 to be the caprylic, caproic and valerianic acids. 



Human fat, which M. Lerch very carefully examined, and 

 in large quantities, gave, with the known margaric and oleic 

 acids, a considerable quantity of volatile fatty acids besides 

 caprylic acid, so that the barytic salt of the latter could be 

 clearly established. As before stated, the weakened odour of 

 caprylic acid brings to my mind the ordinary odour of the 

 perspiration of a healthy man j and it is therefore probable 



