PROTEIDS IN THE URINE. 789 



A confounding with mucin, when this body occurs in the urine, is 

 easily prevented in the heat test with acetic acid by acidifying another 

 portion with acetic acid at the ordinary temperature. Mucin and 

 nucleoalbumin substances similar to mucin are hereby precipitated. If 

 in the performance of the heat and nitric-acid test, a precipitate first 

 appears on cooling or is strikingly increased, then this shows the presence 

 of proteoses in the urine, either alone or mixed with coagulable proteid. 

 In this case a further investigation is necessary (see below). In a urine 

 rich in urates a precipitate consisting of uric acid separates on cooling. 

 This precipitate is colored and granular, and is hardly to be mistaken 

 for a proteose or proteid precipitate. 



HELLER'S test is performed as follows (see page 99): The urine is 

 very carefully floated on the surface of nitric acid in a test-tube, or the 

 urine is placed in a test-tube and then the acid is slowly added by means 

 of a funnel, drawn out to a point, and extending to the bottom. In the 

 presence of albumin a white disk, or as we ordinarily say a white ring or 

 at least a sharply denned cloudiness, appears at the point of contact of 

 the two fluids. With this test a red or reddish-violet transparent ring 

 is always obtained with normal urine; it depends upon the indigo color- 

 ing-matters and can hardly be mistaken for the white or whitish proteid 

 ring. In a urine rich in urates, another complication may occur, due 

 to the formation of a ring produced by the precipitation of uric acid. 

 The uric-acid ring does not lie, like the proteid ring, between the two 

 liquids, but somewhat higher. For this reason two simultaneous rings 

 may exist in urines which are rich in urates and do not contain very much 

 proteid. The disturbance caused by uric acid is easily prevented by 

 diluting the urine with 1-2 vols. of water before performing the test. 

 The uric acid now remains in solution, and the delicacy of HELLER'S 

 test is so great that after dilution only in the presence of insignificant 

 traces of proteid does this test give negative results. In a urine very 

 rich in urea a ring-like separation of urea nitrate may also appear. This 

 ring consists of shining crystals, and it does not appear in urine previously 

 diluted. A confusion with resinous acids, which also give a whitish 

 ring with this test, is easily prevented, since these acids are soluble on the 

 addition of ether. Stir, add ether, -and carefully shake the contents of 

 the test-tube. If the cloudiness is due to resinous acids, the urine gradually 

 becomes clear, and on evaporating the ether a sticky residue of resinous 

 acids is obtained. A liquid which contains true mucin does not .give 

 a precipitate with this test, but it gives a more or less strongly opalescent 

 ring, which disappears on stirring. The liquid does not contain any 

 precipitate after stirring, but is somewhat opalescent. If a faint, not 

 wholly typical reaction is obtained with HELLER'S test after some time 

 with undiluted urine, while the diluted urine gives a pronounced reaction, 

 the presence is shown of the substance which used to be called mucin 

 or nucloealbumin. In this case proceed as described below for the detec- 

 tion of nucleoalbumin. 



If the above-mentioned possible errors and the means by which they 

 may be prevented are borne in mind, there is hardly another test for 

 proteid in the urine which is at the same time so easily performed, so 

 delicate, and so positive as HELLER'S. With this test even 0.002 per 

 cent of albumin may be detected without difficulty. Still the student 

 must not be satisfied with this test alone, but should apply at least a 



