108 CHEMICAL PHYSIOLOGY. 



sugar; and in the urine of a certain percentage of persons 

 apparently enjoying perfect health, minute traces of albumin are 

 sometimes present. When, however, these substances occur in 

 considerable quantity, then their presence is of the utmost 

 practical and diagnostic value, and is distinctly abnormal. It is 

 quite certain that serum-albumin is never found in any con- 

 siderable amount in normal urine. 



1. Albumin in Urine. When albumin occurs in notable quan- 

 tity in the urine, it gives rise to the condition known as 

 albuminuria. 



Various forms of proteid bodies may occur in the urine. The 

 chief one is serum - albumin ; but, in addition, serum-globulin, 

 hemi-albumose, peptone, acid-albumin, and fibrin may be found. 



2. Tests. The demonstrator will procure an albuminous urine. 

 With it perform the following tests. In every case the urine 

 must be clear before testing, which can be secured by careful 

 filtration. 



(a.) Coagulation by Heat. Place 10 cc. of urine in a test- 

 tube and boil. Near the boiling point, if albumin be pre- 

 sent in small amount, it will give a haziness ; if in a large 

 amount, a distinct coagulum. On standing, the coagulum 

 is deposited. Precautions. (i.) Always test the reaction of 

 the urine, for albumin is only precipitated by boiling in a 

 neutral or acid medium. Hence if the urine be alkaline, 

 boiling will not precipitate any albumin that may be present, 

 (ii.) Boil the upper stratum of the fluid first of all, holding 

 the tube obliquely, taking care that the coagulum does not 

 stick to the glass, else the tube is liable to break, (iii.) 

 Heat, by driving off the CO 2 , also precipitates earthy 

 phosphates if they are present in large amount, hence a tur- 

 bidity on boiling is not sufficient proof of the presence of 

 albumin. The points of distinction are, that albumin goes 

 down before the boiling point is reached (coagulated at 

 75 C.), while phosphates are precipitated at the boiling 

 point. Again, the phosphatic deposit is soluble in an acid 

 e.g., acetic or nitric while the albuminous coagulum is in- 

 soluble in these fluids. Some, therefore, advise that the test 

 be done in the following manner : 



(b.) Acidulate the urine with a few drops of acetic or nitric 

 acid, and then boil. If nitric acid be used, add one-tenth to 



