502 Dr. Redtenbacher on a Class of Organic Acids. 



mode of origin has been made known by Pelouze, namely the 

 production of butyric acid by the decomposition of the hy- 

 drate of carbon, of decayed cheese, and of similar bodies ; and 

 the production of butyric acid has been detected by Marchand 

 in sour-krout and in cucumber-water ; and also by Wurz in 

 tainted meat. 



Iljenko and Laskowsky, in Liebig's laboratory, have found 

 a considerable quantity of valerianic acid in half-decayed 

 cheese. Cheese which consists of the ingredients of the milk 

 contains only fat and caseine ; the valerianic acid could only be 

 formed out of these two ingredients. Fresh butter contains 

 no valerianic acid ; Liebig has however obtained by the action 

 of caustic alkali on cheese valerianic and butyric acid. But 

 these last two modes cannot be the ordinary way in which 

 these acids exist in organic bodies. It is not especially to be 

 referred to putrefaction or to cheese. 



It is probable that nature follows a more general course in 

 producing so great a variety of the easily volatile fatty acids. 

 They are combined with the base oxide of lipyle, the constant 

 companion of all the fixed and volatile fatty bodies of the ve- 

 getable and animal kingdom. The different fatty bodies may 

 be submitted to the same process by which the volatile acids 

 are separated from butter, but in every case a very small 

 quantity of these acids is found. 



It is very possible that they proceed either from the fixed 

 acids or from the oily acids of the fat. 



The solid acids, stearic, margaric, palmitic, cocinic, myristic, 

 contain carbon and hydrogen in the same proportions ; they 

 may merely combine with oxygen in order to be converted, in 

 several equivalents, into acids volatile under 300° Centig., 

 (CH)»0 4 . 



But these solid acids are in themselves permanent, and do 

 not undergo change by exposure to the air ; on the contrary, 

 oleic acid is by the action of the oxygen of the atmosphere, 

 and also by other oxidizable agents, a body subject to changes. 

 According to the formula C 36 H^ 4 of Gottlieb, two atoms 

 of carbon must be given off in order that it may be converted 

 into the acid (CH)„ 4 . 



Laurent and Bromeis having examined the oxidizing action 

 of nitric acid on the oily acids, the one considered he had 

 found in them cenanthic acid, the other that he had found 

 butyric acid. Tilley, by the action of nitric acid on castor oil, 

 also produced an acid of this class ; and still later, Gottlieb, 

 by dry distillation, which is partly an oxidizing process, ob- 

 tained capric and caprylic acids from oleic acid. 



The foregoing considerations have induced me to study the 



