THE URINE. 295 



ceives that it is in the state of urate of ammonia, which is 

 decomposed by the other acids when it cools : while others fancy 

 that the solution in the urine of substances so little soluble is 

 a fact analogous to that of iodine being so much more soluble in 

 water charged with chloride of sodium or ammonia. 



Urea is in the form of slender four-sided prisms, colourless, 

 inodorous, and deliquescent, and affords a cool taste like nitre : 

 it reacts as neither an acid nor an alkali. 



It is a common mistake, even at present, to ascribe the colour 

 and smell of urine to it. Whoeler has shown that urea is a cya- 

 nite of ammonia. Dr. Prout has established that it consists of 

 Hydrogen - -266 



Carbon w&p - -799 



Nitrogen - 1-866 



Oxygen - 1-066 



4-000 * 



The large proportion of nitrogen in urea leads to the conclu- 

 sion that the kidneys are the great outlet for azote, as the 

 lungs and liver are for carbon. 



In disease, the specific gravity may exceed 1050, and the 

 quantity has been greater than thirty pounds a day. Dr. Peter 

 Frank had a patient who made forty pounds every twenty-four 

 hours, and occasionally fifty-two pounds a ; and he knew it exceed 

 the weight of the body in a few days. On the other hand, no urine 

 has sometimes been secreted for twenty -two weeks. I Dr. Richard- 

 son mentions a lad of seventeen who had never made any, and 

 yet felt no inconvenience. 2 In disease, and even during such 

 little derangements as are scarcely considered disease, the urine 

 deposits sediments, lateritious and pink ; and Dr. Prout has shown 

 that they consist chiefly of the urate of ammonia, and states that 

 they are formed from the albuminous portions of the chyle. The 

 red colour he has shown to depend upon the presence of the pur- 

 purate of ammonia, a substance formed from the uric acid, and 

 which, like the other purpurates, colours the urates pink. ' When 

 the usual yellow colouring matter is present, this, with the pink, 



* Med. Chir. Trans, vol. viii. p. 535. 



y Haller, Biblioth. Medic, vol. ii. p. 200. 



z Phil. Trans. 1713. He had a constant diarrhoea. 



* De curandis hominum morbis, lib. v. p. 44. 



