BILE IN URINE. 27 



of the presence of albumen. Either alone would, however, 

 occasionally lead us into error. 



As the urine of dogs contains a considerable amount of 

 phosphates, and as these salts are, under certain circum- 

 stances, precipitated when the urine is boiled, and then 

 resemble precisely a precipitate of albumen, unless we 

 added nitric > acid, we might mistake the phosphates for 

 albumen, and suppose the dog to be suffering from a disease 

 of the kidneys, when in reality these organs were perfectly 

 healthy. 



On the other hand, the urine of dogs may sometimes con- 

 tain an excess of the salts of uric acid (urates) in solution ; 

 in such cases, the addition of a few drops of nitric acid to 

 the urine would throw down a precipitate; we should then 

 be in doubt whether this precipitate consisted of albumen or 

 urates. On boiling the fluid, the precipitate would either be 

 immediately dissolved, or not affected; in the former case, we 

 should be certain that urates, in the latter, that albumen, 

 were present 



The colouring matter of the bile finds its way into the 

 urine in certain diseases of the liver. It causes the secretion 

 to assume a more or less yellow or porter-like appearance. 

 When such urine is poured into a plate, and nitric acid is 

 gradually added, rings of a blue, violet, and red colour are 

 gradually formed. 



It has lately been asserted by Dr Harley, that the acids of 

 the bile are found in the urine, in all cases of jaundice, from 

 obstruction, that is to say, where the bile is mechanically 

 prevented from entering the intestine.* 



* The detection of these bodies is made by Pettenkoffer's test, as 

 the di faculties in drawing conclusions from this test are greater than in 

 the case of the bile colouring matter, and as Dr Harley's conclusions 

 are contrary to those arrived at by many other distinguished chemists, 



