THE MICROSCOPE IN PATHOLOGY AND MEDICINE. 237 



necessary in disease. It may be done by acidulating the 

 urine with a few drops of nitric acid, and then adding 

 nitrate of silver. The precipitate should then be dried 

 and fused in a porcelain capsule before weighing. 



Albumen in suspected urine may be tested by boiling in 

 a test-tube, when it will be coagulated. As a white pre- 

 cipitate sometimes occurs from an excess of earthy phos- 

 phates, a few drops of nitric acid should be added, which 

 dissolves phosphates, but coagulates albumen. 



Diabetic sugar is recognized by several tests. Moore's 

 test is made by mixing the urine with half its bulk of 

 liquor potassae, and boiling gently for five minutes. Sugar 

 gives the liquid a brown or bistre tint. Trommer's test 

 consists in boiling the urine with a mixture of caustic 

 potash and sulphate of copper, when if sugar be present 

 the suboxide of copper will be reduced to a reddish-brown 

 or ochre-colored powder. Fehling's test solution is a 

 modification of the last, and is made by dissolving 69 

 grains of sulphate of copper in 345 grains of distilled 

 water; to this is added a concentrated solution of 268 

 grains of tartrate of potash, and then a solution of 80 

 grains of carbonate of soda to 1 ounce of water, and the 

 whole diluted to 1000 grains. The fermentation test 

 consists in filling a test-tube with urine, to which a little 

 yeast is added. The tube is then inverted over a saucer 

 containing a little urine, and placed in a warm place for 

 twenty-four hours. If sugar is present, it undergoes 

 vinous fermentation, yielding alcohol and carbonic acid. 

 The latter rises in the tube and displaces the liquid. 



The coloring matter of bile in urine may be detected by 

 the nitric-acid test. A few drops of biliary urine are 

 poured on a white plate, and a drop of nitric acid allowed 

 to fall upon it. As the acid mixes with the fluid, a play 

 of colors, commencing in green, passing through various 

 shades, and terminating in red, will be observed. 



We necessarily omit many chemical details respecting 



