444 PRACTICAL PHYSIOLOGY 



where it is foreign (in being egg- and not serum-albumin), and is con- 

 sequently immediately excreted by the kidneys. In disease of the red- 

 bone marrow, a body somewhat similar in its reactions to a proteose is 

 added to the blood and is excreted by the urine (Bence Jones' proteose- 

 uria). 



Although globulin may occur along with albumin in the urine, or 

 even in some cases independent of it, it is of no practical importance to 

 distinguish between them, so that the tests about to be described 

 include both bodies. 



The tests employed depend on certain of the reactions described under 

 proteins. It is obvious that the colour reactions will not be applicable 

 to the urine; those employed depend on the production of coagula. 

 The most important of these are : 



1. Heat Coagulation. EXPERIMENT I. Place some clear urine in a 

 test tube, and boil. A white turbidity or coagulum indicates the 

 presence of either albumin or phosphates (earthy phosphates are pre- 

 cipitated by boiling). To the boiling solution, whether it show a 

 turbidity or not, add 3-4 drops of concentrated nitric acid. If due to 

 phosphates, the turbidity will disappear, but will remain if due to 

 protein. In nitric acid any acid- or alkali-albumin which the urine 

 may contain is insoluble. Where there is doubt as to the occurrence 

 of a haze, the test tube should be about three-quarters filled, and only 

 the upper layer should be boiled, the test tube being meanwhile held 

 low down. By holding it against a dark background the slightest 

 haze becomes very evident by this method, on account of contrast with 

 the unboiled layer beneath. 



2. Heller's Test. EXPERIMENT II. Place some clear urine in a test 

 tube. Hold the test tube in a slanting position, and allow concentrated 

 pure nitric acid to run very slowly down the side, so that it forms a 

 layer underneath the urine. Where the two meet, a sharp white ring 

 (of coagulated acid albumin) is formed. The test may also be done by 

 placing the nitric acid first in the test tube, and covering this with th& 

 urine slowly delivered from a pipette. The ring does not disappear on 

 warming. A similar ring may be obtained when proteoses are present,, 

 but in this case the ring clears up on gently warming the test tube, 

 and reappears on cooling. In warming, very great care must be taken 

 that no mixing of the two layers occurs. When mucin is present in 

 excess a diffuse haze may be produced in the portion of urine next the 

 acid. Certain resin acids which may appear in the urine after the 

 administration of such drugs as copaiba also give a haze by Heller's 

 test. Also when the urine is very concentrated, acid urates or urea 

 nitrate crystals may develop and simulate the reaction. In these cases,. 



