430 PARA-OXYPHENYL-ACETIC ACID. [BOOK II. 



Para-oxyphenyl-acetic acid, C 8 H 8 3 (HO . C 6 H 4 . CH 2 . CO . OH). 



This acid was obtained by E. and H. Salkowski 1 as a product of 

 the putrefaction of wool and of albuminous bodies, and by Baumann 

 from tyrosin by a process of putrefaction initiated by decomposing 

 pancreas 2 , besides being found by him in the urine, after injection of 

 tyrosin, in phosphorus poisoning, &c. 



Physical and Para-oxyphenyl-acetic acid crystallises from water in 



lemicai pro- ^ Q form of prismatic transparent prisms which are 



readily soluble in water, alcohol, and ether, but soluble 



with difficulty in benzol. It melts at 148 C. and when more strongly 



heated is partly decomposed and partly volatilises unchanged. The 



sulphates of copper, zinc and cadmium precipitate aqueous solutions 



of its ammoniacal salt. 



Acetate of lead does not precipitate dilute solutions of the acid 

 but when added to concentrated solutions occasions a crystalline 

 precipitate, soluble in excess of the precipitant but which sub- 

 sequently slowly separates out again. Under the influence of putre- 

 faction, this acid decomposes, yielding, as products, parakresol and 

 carbon dioxide. 



Re ti ns With solution of iron chloride it gives a pale grey- 



violet, which soon changes to a dirty grey-green colour- 

 ation. 



It exhibits the red reaction when boiled with Millon's reagent. 



Behaviour in This acid, which, as has been said, is found in the 



the organism. urine after tyros i n h as been given with the food, is 

 excreted partly in the pure condition and partly in combination with 

 sulphuric acid 3 . 



Phenyl-acetic acid, -, Phenyl-propionic acid, 



C 6 H 5 . CH 2 . COOH C 6 H 5 . CH 2 . CH 2 . COOH. 



These two acids were discovered in the products of the putre- 

 factive decomposition of albuminous substances by the brothers 

 Salkowski 3 . 



1 E. and H. Salkowski, Ber. d. deutsch. chem. Ges. Vol. xn. p. 650. 



2 Baumann, Zeitsch. f. phys. Chem. Vol. iv. (1880), p. 305. 



3 E. Salkowski, ' Zur Kenntniss der Pancreasverdauung (vorlaufige Mittheilung),' 

 Zeitsch. f. physiol. Chemie, Vol. n. (187879), pp. 420424. In the ' Nachschrift ' to 

 this paper the Author announces that his brother had identified the acid of which it 

 it treated as phenyl-acetic acid ; see also E. and H. Salkowski, Ber. d. d. chem. Gesell. 

 Vol. xii. (1879) pp. 107 and 653. 



E. Salkowski, 'Zur Kenntniss der Eiweissfaulniss II. Die Skatolcarbonsaure, ' 

 Zeitsch. f. phys. Chemie, Vol. ix. (1885), pp. 8 22. The volatile aromatic acids are 

 referred to and the scheme for their separation indicated (pp. 10 17), 



E. Salkowski, Zur Kenntniss der Eiweissfaulniss III. Ueber die Bildung der nicht 

 hydroxylirten aromatischen Sauren,' Zeitsch. f. phys. Chemie, Vol. ix. (1885), pp. 491 

 510. 



