HAP. IV.] 



CHOLALIC ACID. 



305 



of in separating it from the higher members of the fatty acid series. 

 The lead and silver salts are insoluble in water but soluble in hot 

 alcohol. 



Mylius's iodine Cholalic acid forms with iodine a remarkable corn- 

 compound. pound, which furnishes us with a reaction by which we 

 can distinguish it from the conjugated bile acids, as well as from 

 other acids closely connected with cholalic acids, as choleic acid and 

 hyocholalic acid. 



0*02 grm. of crystallised cholalic acid dissolved in 0'5 grm. of 

 alcohol is treated with one-tenth of a c.c. of decinormal solution of 

 iodine, and water is then very gradually added to the solution. 

 The liquid, which was at first brown, becomes pervaded by a magma 

 of microscopic needles which by reflected light exhibit a metallic 

 lustre, and by transmitted light appear of a blue colour. This 

 compound, like the compound of starch with iodine, is dissociated 

 with remarkable facility by heat, and the addition of water suffices 

 to break it up into iodine and cholalic acid. 



Considerable difference of opinion has existed as to 

 the empirical formula of cholalic acid. Latschinoff 1 

 maintained that the formula of the acid should be 

 C^H^Og instead of C 24 H 40 O 5 , the formula based on Strecker's 

 researches. Mylius 2 , however, from his own very elaborate and 

 conclusive researches, as well as from the analyses of cholalic acid 

 made by Strecker and by Schotten 3 conclusively establishes that the 

 empirical formula C 24 H 40 O 5 agrees much better with experimental 

 facts than the formula proposed by Latschinoff. 



Action of cer- i. Dehydrocholalic acid, C 24 H 40 5 . By the action 

 of a 10 P er cent - solution of chromic acid on a 10 

 1^ P tC< s l u tion of cholalic acid in glacial acetic acid, 

 at ordinary temperatures, Hammarsten 4 obtained the 

 acid to which he assigned the name dehydrocholalic acid ; this acid 

 crystallises from alcohol in the form of needles. It does not give 

 Pettenkofer's reaction. Its alkaline salts dissolved in alcohol are 

 precipitated by the addition of ether and furnish a crystallisation 

 resembling Plattner's crystallised bile. 



The sodium salt in aqueous solution has a specific rotation 



Empirical 

 formula of 

 cholalic acid. 



laiic acid 



1 P. Latschinoff, ' Ueber die Gallensauren.' Ber. d. d. chem. Gcsellsch., Vol. xx. 

 (1887), 10431053; 'Ueber die empirische Formel der Cholsaure.' Ibid. Vol. xx. p. 

 3274. 



2 F. Mylius, ' Ueber die Cholsaure.' Ibid. Vol. xx. 1968 et seq. 



3 C. Schotten, ' Zur Kenntniss der Gallensauren.' Zeitschrift f. physiol. Chemie, 

 Vol. x. (1886), pp. 175217. Refer to ' II. Taurocholsaure,' pp. 190 and 191. 



4 0. Hammarsten, ' Ueber Dehydrocholalsaure ein neues Oxydationsproduct der 

 Cholalsaure.' Nova A eta Reg. Soc. Scient. Upsal., Serie in. 1881. A full abstract of 

 the paper by its author appeared in Maly's Jahresbericht, Vol. xi. (1882), pp. 313 315. 



G. 20 



