ALBUMIN TESTS. 181 



is not as sensitive as some others. This decomposition is greatly 

 increased if the urine is boiled after adding the acid. Besides 

 albumin, there may be precipitated by this test uric acid from the 

 urates in very concentrated normal urine, and also resinous matters 

 after the administration of turpentine or the balsams. The resin- 

 ous compounds are soluble in alcohol, which does not dissolve albu- 

 min. The uric-acid compounds are colored instead of being white, 

 like albumin, and can be filtered out and tested. 



The ring-test with nitric acid is very sensitive. It precipitates 

 other substances than albumin, such as the urates, mucin, and 

 resinous substances. The urates do not form a ring at the plane 

 of contact of the two liquids, but above it; and if the urine is 

 previously diluted with two or three times its volume of water 

 they do not appear. The resinous matters dissolve in alcohol. The 

 mucin precipitate forms a cloud in the upper part of the liquid 

 where the acid is dilute. It dissolves in strong nitric acid. 



Potassium ferrocyanid and acetic acid will detect very small 

 quantities of albumin. Albumose is also precipitated if present. 

 If the acid alone produces a cloudiness it is mucin or resinous com- 

 pounds. These must be removed by filtration before adding the 

 ferrocyanid. 



In the sodium chlorid and acetic acid test the precipitate 

 formed on boiling is acid albumin, which is insoluble in the salt 

 solution. Resinous matters may be precipitated, but not mucin. 



384. DETERMINATION OF AMOUNT OF ALBUMIN IN 

 URINE BY ESBACH'S METHOD. The urine must not have 

 a specific gravity above 1.008, otherwise it must be diluted. 

 If it is not distinctly acid in reaction it must be made so 

 by acetic acid. Fill the albuminometer with urine to the 

 mark U. Add the reagent to the mark R. Close with a 

 cork and mix gently, avoiding hard shaking, which intro- 

 duces air bubbles into the precipitate and thereby prevents 

 its settling. Let it stand at the temperature of the room 

 (60 to 70 F.) for twenty-four hours. The height of 

 the precipitate indicates the number of grammes of albu- 

 min per liter, or parts in a thousand. 



