262 THE URINE. 



stances mentioned are ingested as such or otherwise introduced into 

 the circulation from without. A notable increase is thus observed 

 in poisoning with carbolic acid or its congeners, and is then, of 

 course, principally owing to an increased formation of phenol sul- 

 phates. The ingestion of ortho-nitro-phenyl-propiolic acid, which 

 is reduced to indoxyl within the body, similarly leads to an increased 

 elimination of indoxyl sulphate. 



The synthesis of the various conjugate sulphates is largely 

 effected in the liver, but may also occur in other organs of the 

 body, such as the kidneys and lungs. In some experiments posi- 

 tive results were also obtained in the case of the muscle-tissue and 

 the intestinal wall, but these organs play only a secondary role as 

 compared to the liver. Their quantitative estimation in toto has 

 been described. 



The Phenols. Of the phenols which occur in the urine, para- 

 cresol is the most abundant; next in order comes phenol, while 

 pyrocatechin and hydroquinon are found only in traces. Besides 

 paracresol, the normal urine of man is said also to contain minute 

 amounts of meta- and ortho-cresols. The total elimination of 

 cresols and phenols, however, normally corresponds to only about 

 0.03 gramme in the twenty-four hours. 



Urine which contains much hydroquinon or pyrocatechin gradually 

 assumes a dark-brown color on standing if the reaction is alkaline, 

 and it is noted that this change in color begins in the upper layers 

 and gradually extends downward. Ultimately the urine becomes 

 almost black. This change is referable to oxidation of the dioxy- 

 benzols, but of the resulting compounds nothing is known. Urines 

 of this character are mostly observed in poisoning with carbolic acid, 

 following the administration of benzol, of phenol sulphates, etc. 



To demonstrate the presence of phenol or of paracresol, 1000 

 c.c. of urine are treated with 70 c.c. of concentrated hydrochloric 

 acid, and distilled until about one-fourth of the total amount 

 has passed over. The conjugate sulphates are thus decomposed, 

 and phenol and cresol are found in the distillate. Their presence 

 can here be demonstrated by testing with Millon's reagent or by 

 adding bromine-water, when tribromophenol crystallizes out on 

 standing. If much phenol is present, it may further be possible to 

 obtain a positive reaction with ferric chloride solution if this 

 is added drop by drop in very dilute solution (an amethyst- 

 blue color resulting). Hydroquinon and pyrocatechin remain 

 in the acid solution. To demonstrate their presence, this is 

 evaporated to about 100 c.c., and on cooling extracted with an 

 equal volume of ether. Hydroquinon and pyrocatechin together 

 with the aromatic oxy-acids are thus removed. On adding 

 a dilute solution of sodium carbonate to the ethereal solu- 

 tion the aromatic oxy-acids are transformed into the corresponding 

 sodium salts. The ethereal extract, which now contains only the 

 dioxy-benzols, is evaporated to dryness ; the residue is dissolved in 



