CHEMICAL BASIS OF THE ANIMAL BODY. 127 



This acid has not yet been prepared synthetically and is only known 

 as occurring characteristically in muscles l to which it gives their acid re- 

 action 2 , and in blood 3 . In the latter it is found more particularly, as 

 might be expected, after the muscles have been in a state of contracting 

 activity 4 . It is also found in urine, very markedly in cases of phosphorus 

 poisoning and in the same excretion after violent muscular exertion 5 , 

 or artificial stimulation of groups of muscles 6 , and very strikingly after 

 extirpation of the liver in birds 7 , arid frogs 8 . It is also stated to be 

 formed in variable and slight amount during the lactic fermentation of 

 dextrose 9 . Lactic acid has also been frequently described as a consti- 

 tuent of various pathological fluids ; in these cases it is probable that 

 the acid is often the sarcolactic acid 10 . 



As occurring characteristically in muscles it is hence found in large 

 quantities in Liebig's ' extract of meat ' which is the most convenient 

 source for its preparation 11 . 



Liebig's extract is dissolved in four parts of warm water. To this solution two 

 volumes of 90 p.c. alcohol are added and the precipitate is removed by nitration. 

 The filtrate, after concentration, is again precipitated with four volumes of alcohol. 

 The filtrate from this second precipitate is finally concentrated, acidulated with 

 sulphuric acid and extracted with excess of ether which dissolves out the sarcolactic 

 acid. On evaporating off the ether and dissolving the residue in water, the pure 

 acid may be obtained by forming its zinc salt, which is purified by crystallisation 

 and decomposed by sulphuretted hydrogen. 



For the method of detecting and separating this acid from urine see Salkowski 

 and Leube 12 . 



The zinc and calcium salts of sarcolactic acid are much more soluble 

 both in water and alcohol than are those of ethylidene-lactic acid. 



Zinc sarcolactate. Zn (C 3 H 5 O 3 ) 2 + 2H 2 0. Soluble in 17'5 parts of 

 water at 15 or 964 parts of boiling 98 p.c. alcohol. 



Calcium sarcolactate. Ca (C 3 H 5 O 3 ) 2 + 4H 2 [? 4J H 2 0]. Soluble in 

 12-4 parts of cold water, soluble in all proportions in boiling water 

 or alcohol. 



1 Wislicenus, Ann. d. Chem. u. Pharm. Bd. CLXVII. (1873), S. 302. 



2 Liebig, Ann. d. Chem. u. Pharm. Bd. LXII. (1847), S. 326. 



3 Gaglio, Arch. f. Physiol. Jahrg. 1886, S. 400. 



4 Spiro, Zt. f. physiol. Chem. Bd. i. (1877), S. 111. Of. Von Frey, Arch. f. 

 Physiol. Jahrg. 1885, S. 557. Also Marcuse, loc. cit. below. 



5 Colasanti and Moscatelli. See ref. in Maly's Bericht. 1887, S. 212. 



6 Marcuse, Pfliiger's Arch. Bd. xxxix. (1886), S. 425. 



7 Minkowski, Centralb. f. d. med. Wiss. 1885, No. 2. Arch. f. exp. Path. u. Phar- 

 makol. Bd. xxi. (1886), S. 40. 



8 Marcuse, loc. cit. But see Nebelthau, Zt. f. Biol. Bd. xxv. (1889), S. 123. 



9 Maly, Ber. d. d. diem. Gesell. Jahrg. 1874, S. 1567. 



10 Cf. Maly. Abst. in Maly's Jahresb. 1871, S. 333. Fluid from ovarial cyst. 



11 See Gamgee, Physiol. Chemistry, Vol. i. 1880, p. 361. 



12 Die Lehre vom Earn, 1882, S. 125. 



