The Urine. 213 



those mentioned are generally at hand and readily ap- 

 plied. 



Albuminuria is a rare disease amongst horses as the 

 result of kidney affection, but common enough in many 

 febrile states of the system ; for instance, in pneumonia it 

 is exceedingly common, and its presence or absence a 

 valuable guide in forming an opinion of the case. 



Sugar in the urine is distinctly rare, though other sub- 

 stances may be present which give a sugar reaction and yet 

 are not sugar. 



Sugar is detected by adding to urine a few drops of a 

 weak solution of copper sulphate and an excess of caustic 

 potash; the fluid is boiled, and if sugar be present the 

 whole is turned yellow or red, and throws down a brick-red 

 deposit of the suboxide of copper. 



The only error which can be made in this test is taking 

 for suboxide of copper the precipitate which always forms 

 in urine when boiled with copper and potash ; the pre- 

 cipitate is brown, and the fluid is not turned yellow or red. 



Substances may be present in urine other than sugar 

 which reduce copper. When this is suspected, the only 

 reliable clinical test is the fermentation one : yeast is mixed 

 with the urine in a test-tube inverted over mercury, and if 

 sugar be present it undergoes fermentation, C0 2 is given 

 off' and collects in the tube. 



Bile. — In many cases of liver di&ease it is important to 

 know whether any of the bile pigments or bile acids are 

 passing out with the urine. For this purpose a drop or 

 two of the urine is placed on a white plate and touched 

 with a rod dipped in strong common nitric acid ; a play of 

 colours occurs — green, blue, violet, red, and orange. This 

 test, known as Gmelin's, is characteristic of the bile pig- 

 ments. (See p. 161.) 



The bile acids are recognised in urine by what is known 

 as Pettenkoffer's test. To the urine in a test-tube is added 

 a strong solution of cane-sugar, followed by a few drops of 

 strong sulphuric acid ; a purple colour is indicative of the 

 presence of glycocholate and taurocholate of soda. 



