56 

 XX. 



263. Albumin in urine. The presence of this substance 

 in the urine is regarded as pathological. It must be borne 

 in mind, however, that in the urine of a certain percentage 

 of persons apparently enjoying perfect health, minute 

 traces of albumin are sometimes present and, unless these 

 traces persist, are not to be regarded as serious. If present 

 in any considerable quantity, it must be regarded as dis- 

 tinctly abnormal. The most common cause of the appear- 

 ance of the albumin is disease of the kidney (Bright's 

 disease). Albuminuria is the term applied when albumin 

 occurs in notable quantity in the urine. The chief form of 

 albumin present is serum-albumin ; in addition there may 

 be serum-globulin, albumose, peptone, acid-albumin and 

 fibrin. 



264. In every case the urine must be clear before te.sting, 

 by filtering it carefully. 



Add a little acetic acid to the urine. Boil in a test-tube. 

 Near the boiling point, if in small amount, the albumin will 

 show a haziness ; if in large amount, there will be a distinct 

 coagulum. 



Caution. If the urine be alkaline, boiling will not pre- 

 cipitate the albumin. Heat, by driving off the CO2, also pre- 

 cipitates the earthy phosphates, if they are present in large 

 amount. Albumin, however, is coagulated before the boil- 

 ing point is reached — 73° C. — while the phosphates are pre- 

 cipitated at the boiling point, 100° C. The phosphates are 

 soluble in nitric acid, the albumin is not. When nitric acid 

 is added, it is believed that some of the albumin is still kept 

 in solution as an acid-albumin, so that the test is not re- 

 garded as the most accurate one. Nitric acid in excess will 

 dis.solve the albumin. 



265. Heller's cold nitric acid test. Pour some of the 

 urine gently upon the surface of some nitric acid in a test- 

 tube. A ring of white coagulum occurs at the junction of 



