ALLANTOIN, COLORING-MATTERS OF THE URINE. 



485 



the hippuric acid formed is already decomposed in the blood and the tissues 

 of man is doubtful. In the kidneys of swine and of the dog, fermentative decom- 

 position of hippuric acid takes place. 



After ingestion of pears, prunes, cranberries, unpeeled apples, the amount of 

 hippuric acid increases greatly. It is increased also in the presence of jaundice, 

 diseases of the liver, and diabetes. If it be contained in the urine in large amounts, 

 it appears in the sediment, from which it can be isolated by boiling with alcohol. 

 Boiled in strong acids or alkalies, or in combination with putrid substances or 

 the micrococcus ureae, it is decomposed again into benzoic acid and glycin, with 

 the taking up of water. 



The urine of the dog contains, in addition to uric acid, kynuric acid, 

 C 10 H 14 N 3 O 6 + H 2 O, and uroprotic acid, C 66 H 116 N 2rt SO 54 + H 2 O. 



Allantoin, C 4 H 6 N 4 O 3 , a constituent of the amniotic fluid of the cow, in lesser 

 degree of that of human beings, is 

 normally present in the urine in 

 traces, especially after the eating of 

 meat; in larger amount in the first 

 week of life and in pregnant women, 

 as well as after administration of 

 thymus gland and pancreas. The 

 amount increases after the ingestion 

 of considerable amounts of tannic 

 acid; in the dog, from the oxidation 

 of uric acid fed. 



Allantoin forms glistening, pris- 

 matic crystals. It crystallizes in 

 transparent prisms from the urine of 

 nursing calves on evaporation to a 

 sirupy consistence, and standing at 

 rest for a day. It is decomposed by 

 ferments into urea, ammonium oxa- 

 late and carbonate, and another sub- 

 stance whose identity has not yet 

 been established. It is readily sol- 

 uble in water, with difficulty in alco- 

 hol, and not at all in ether. For its 

 preparation, the urine is precipitated 

 by means of basic lead acetate, the 

 lead being removed from the nitrate 

 by means of hydrogen sulphid. The fluid is then evaporated to a sirupy consist- 

 ence, and the crystals separate in the course of days. These are washed with water 

 and recrystallized out of hot water. 



Oxyproteic acid is an oxidation-product of albumin containing nitrogen and 

 sulphur. It can be prepared as a baryta-combination, is soluble in water but 

 not in alcohol, and is precipitable by mercuric nitrate and sulphate. On a 

 mixed diet, it constitutes from 2 to 3 per cent, of the total nitrogen, thus some- 

 what more than the uric acid. It is greatly increased in cases of phosphorus-poison- 

 ing, and perhaps also in conjunction with other forms of proteid decomposition. 



FIG. 150. Hippuric Acid. 



COLORING-MATTERS OF THE URINE. 



Urobilin is present in considerable amount in highly colored febrile 

 urine, often also in normal urine, particularly after the ingestion of 

 readily digestible food and after the termination of gastric digestion; 

 in small amount in the state of hunger and during the process of gastric 

 digestion. It is a derivative of hematin, or of the biliary coloring- 

 matter resulting therefrom. It closely resembles the hydrobilirubin of 

 Maly, from which, however, it differs in the greater amount of nitro- 

 gen it contains. It gives the urine a red or reddish-yellow color, which 

 becomes yellow after admixture with ammonia. 



Urobilin can be extracted from some urine by agitation after addition of 

 an equal volume of ether or chloroform. The urobilin passes over into the latter, 



