Mr. W. Crowder on the Fatty Acid of Cocculus indicus. 31 



from a " source " at a given temperature, when the range down 

 to the temperature of the cold part of the engine or the " refri- 

 gerator " is finite, will diifer most materially from that of Car- 

 not; since, a finite quantity of mechanical effect being now 

 obtained from a finite quantity of heat entering the engine, a 

 finite fraction of this quantity must be converted from heat into 

 mechanical effect. The investigation of this expression, with 

 numerical determinations founded on the numbers deduced from 

 Regnault^s observations on steam, which are shown in Tables I. 

 and II. of my former paper, constitutes the second part of the 

 paper at present communicated. 



[To be continued.] 



III. On the Fatty Acid of Cocculus indicus. 

 By Mr. W. Crowder, Assistant to By. Anderson of Edinburgh^. 



IN a paper published several years ago in the Annalen der 

 Chemie und Pharnjacief upon the substances obtained from 

 Cocculus indicus, Dr. Francis pointed out the existence of a fatty 

 acid which had not previously been subjected to investigation, to 

 which he gave the name of stearophanic acid ; and after analy- 

 sing it, its aether and silver salt, he gave the formula C^'^'^H^^O'' 

 as representing its constitution. The recent researches of che- 

 mists having pointed out that all the fatty acids have the same 

 general formula {C^E.^)'^0'*, and the acid under consideration 

 being evidently a member of that series, it seemed probable that 

 its true formula would be C'^H^O'', with which the results ob- 

 tained by Dr. Francis, when calcidated with the corrected atomic 

 weight of carbon, closely agree. This formula has indeed been 

 since assumed by Dr. Francis himself and by other chemists, as 

 the true expression of his results j and as the investigation of 

 the fatty acids has since the date of his experiments made great 

 strides, I thought it desirable to submit the fat of Cocculus 

 indicus to a new examination, the result of which has fully con- 

 finned the correctness of Dr. Francises numbers, and conclu- 

 sively established the formvda C^'H^''0'*, and consequently the 

 identity of the acid with the bassic acid since described by 

 Mr. Hardwicke J . My experiments were performed in the labora- 



* Communicated by tbe Author. 



+ See also Phil. Mag. for September 1842. 



X [Why, under these cireumstances, the author retains the name of bassic 

 acid we are at a loss to understand. The name stenrophanic, derived from 

 the properties of the sul)stance, is surely iircferable to either that of cnccnlo- 

 stearic su^f,'ested by Berzelius, or of bussic jjroposed by Mr. Hardwicke 

 from its occurrence in Bassia lalifolio ; especially as the recent researches of 

 Ilcintz go to prove that its occurrence is not restricted to the vegetable king- 

 dom, but that it likewise forms one of the constituents of human fat. — W. F.] 



