CHEMICAL BASIS OF THE ANIMAL BODY. 195 



part however is excreted in the urine as an ethereal salt of sulphuric 

 acid, viz. phenylsulphate of potassium. The latter is typical of an 

 extensive series of similar ethereal sulphates which make their appear- 

 ance in urine after the ingestion of aromatic substances. 



Their nature and constitution was first definitely ascertained by 

 Baumann 1 , although it had previously been shown that phenol, even 

 after it has been administered as such, does not exist in the free state 

 in urine but may be set free by distillation with a mineral acid 2 . 



Phenyl-sulphuric acid 3 . C 6 H 5 . O . SO 2 OH. Apart from its abundant 

 presence in urine as an alkaline salt after the administration of phenol 

 this compound occurs normally in small quantities in most urines, more 

 particularly in those of herbivora, since in these animals the conditions 

 for its formation are especially provided by the preponderance of 

 aromatic compounds in their food and the more marked activity of 

 putrefactive changes in their alimentary canal. The total sulphates in 

 urine consist therefore partly of this ethereal sulphate (together with 

 the similar compounds of kresol, indol and skatol, see below) and of 

 ordinary sulphates. The relative amounts of the sulphuric acid con- 

 tained in these two forms is ascertained by acidulating with acetic acid 

 and adding barium chloride by which the sulphuric acid present as 

 ordinary sulphates is precipitated as barium sulphate. The filtrate 

 from this is now boiled with hydrochloric acid by whose action the 

 ethereal sulphates are decomposed, yielding phenol and sulphuric acid 

 which again forms barium sulphate ; from this the amount of the 

 ethereal salts of sulphuric acid may be at once determined 4 . While 

 the probable mode of formation of this acid is undoubtedly due to the 

 primary production of phenol by putrefactive processes from proteids, 

 and the subsequent colligation of this phenol with sulphuric acid, very 

 little is known of the seat or mode of this union. It has not been 

 definitely connected, if at all, with any distinctly synthetic activity of 

 the kidney 5 . 



Since, as has been said, phenol does not exist in the free state in 



1 Pfluger's Arch. Bd. xin. (1876), S. 285. Ber. d. d. chem. GeselL 1876, S. 55. 

 Baumann und Herter, Zt. f. physiol. Chem. Bd. i. (1877), S. 244. See also 

 Baumann, Ibid. Bd. n. (1878), S. 335, Bd. x. (1886), S. 123. For a list of 

 substances, which when administered leave the body as ethereal sulphates see 

 Hermann's Hdbch. d. Physiol. Bd. v. Th. 1, S. 508. 



2 Buliginsky, Hoppe-Seyler's Med. chem. Unters. Hft. 2, 1866, S. 234. Hoppe- 

 Seyler, Pfluger's Arch. Bd. v. (1872), S. 470. 



3 Not to be confounded with phenolsulphonic acid C 6 H 4 (OH) . S0 2 OH. 



4 For the accurate separation of the ethereal sulphates which usually occur 

 mixed in urine some special works should be consulted such as Neubauer u. Vogel, 

 Analyse des Harris or Salkowski u. Leube, Die Lehre vom Harn. Cf. Baumann, Zt. 

 f. physiol. Chem. Bd. i. (1876), S. 70, Ibid. Bd. vi. (1882), S. 183. 



5 Christiani u. Baumann, Zt.f. physiol. Chem. Bd. n. (1878), S. 350. See also 

 Kochs, Pfluger's Arch. Bd. xx. (1879), S. 64. 



