ABNORMAL CONSTITUENTS OF THE URINE. 109 



one-twentieth of the volume of urine. Precautions. If the 

 urine contain only very minute traces of albumin, the latter 

 may not be precipitated if too much nitric acid be added, as 

 the acid-albumin is kept in solution. If too little acid be 

 added, the albumin may not be precipitated, as only a part 

 of the basic phosphates are changed into acid phosphates, 

 and the albumin remains in solution as an albuminate (a 

 compound of the albumin with the base). On heating the 

 urine of a person who is taking copaiba, a deposit may be 

 obtained, but its solubility in alcohol at once distinguishes 

 it from coagulated albumin. This test acts with serum- 

 albumin, and globulin, and if the deposit occurs only after 

 cooling, also with albumose, but not with peptone. 



(c.) Acidulate 10 cc. of the urine with acetic acid, add 

 one fifth of its bulk of a saturated solution of magnesic or 

 sodic sulphate, and boil = a precipitate. 



(d.) Heller's Cold Nitric Acid Test Take a conical test- 

 glass, and place in it 15 cc. of the urine. Incline it, and 

 pour slowly down its side strong nitric acid = a white cloud 

 at the line of junction of the fluids. Precautions. A crystal- 

 line deposit of urea nitrate is sometimes, though very rarely, 

 obtained with a very concentrated urine. If the urine 

 contain a large amount of urates, they may be deposited by 

 the acid, but the deposit in this case occurs above the line 

 of junction, and disappears on heating. It is not obtained 

 if the urine be diluted beforehand. 



(e.) Acetic Acid and Potassium Ferrocyanide. Acidify 

 strongly with acetic acid, and add a solution of potassium 

 ferrocyanide = a white precipitate, varying in amount with 

 the albumin present. The reaction may be done as follows : 

 Mix a few cc. of moderately strong acetic acid with some 

 solution of potassic ferrocyanide, and pour this over some 

 urine in a test-tube by the contact method (d.) The presence 

 of albumin is indicated by a white deposit in the form of a 

 ring at the line of junction of the fluids. A solution of 

 platino-potassic cyanide may be used instead of the ferro- 

 cyanide. The solution of the former is colourless. This 

 test precipitates serum-albumin, globulin, albumose, but not 

 peptone. 



(/.) Picric Acid. Use a saturated watery solution, and apply 



