Dr. Redtenbacher on a Class of Organic Acids. 503 



oxidizable products arising from the action of nitric acid 

 upon oleic acid, but not with the view of repeating or con- 

 trolling the experiments of Laurent and Bromeis : I have not 

 occupied myself with the products which these two chemists 

 have obtained, but only examined the volatile substances 

 given off on oxidation by the action of nitric acid ; I have 

 discovered the before-mentioned series of acids volatile under 

 300° Centigrade. The oleic acid which served for my expe- 

 riments was obtained from the stearine factory of this place ; 

 it is exclusively obtained from the fat of oxen. It contained 

 some tallow and margaric acid, which did not essentially in- 

 terfere with the following experiments. When pure stearine 

 is acted upon by soda, and the solution very much concen- 

 trated, the decomposition, which is subsequently effected by 

 an acid, gives off" the smell of butyric acid ; the separated 

 oleic acid melts under 70° C, so that there remains no doubt 

 that even the fixed acids by oxidation give off acids volatile 

 at 300° C, (CH) n 4 . 



I made use of a very spacious tubulated retort to effect the 

 oxidation of about 10 gallons contents, the neck of which 

 was furnished with a cooling apparatus. 5 lbs. of the strong- 

 est brown fuming acid were poured in, and a funnel provided, 

 whose lower opening dipped into the nitric acid. The acid 

 was slightly warmed, and the oil carefully introduced in small 

 portions at a time. Upon each addition of oil a violent action 

 took place ; it was necessary to wait until the previous action 

 had subsided before any fresh addition of oil was made. The 

 thick brown fumes condensed partly in the water of the re- 

 ceiver through which it passed. Sometimes drops of oil ap- 

 peared on it, and the passing nitrous gas smelt strongly of 

 volatile fatty acids. After 2 or 3 lbs. of oleic acid had been 

 added, the further oxidation was assisted by heat. When, 

 after long heating, a quantity of oil remains on the surface, 

 a fresh portion of nitric acid may be added, using the same 

 precautions as when the oil was added. In this way I have 

 digested 3 or 4 lbs. of oleic acid for several days with nitric 

 acid. At last I obtained, by the addition of water and redi- 

 stillation, all the volatile products contained in the retort. The 

 products of the distillation were partly saturated with potash 

 and subjected to a fresh distillation. In the retort there re- 

 mained nitrate of potash ; strata of volatile fatty acids floated 

 upon the surface of the colourless distilled product, and 

 the easily soluble acids were dissolved in the water. The oily 

 portion was drawn off by a siphon and neutralized by baryta 

 water, the different acids separated by crystallization. It con- 

 tained all the acids, from the valerianic to the capric. The 



