430 A MANUAL OF PHYSIOLOGY 



acetic acid by drops as long as the precipitate seems to be increased 

 Filter through a weighed filter. Wash the precipitate on the filter 

 with hot water, then with hot alcohol, and finally with ether. Dry 

 in an air-bath at 110 C., and weigh between watch-glasses of known 

 weight. 



(b) Method of Roberts and Stolnikow (modified by Brandberg}. 

 This method is founded on the fact that the time taken for the white 

 ring to appear in Heller's test depends on the proportion of coagulable 

 proteid present. It has been found that when i part of albumin is 

 contained in 30,000 parts of an albuminous solution (0*0033 per cent.), 

 the ring appears in two and a half to three minutes. The amount of 

 dilution of the urine which is necessary to delay the formation of the 

 ring for this length of time is what has to be determined. To do 

 this, proceed as follows : Dilute a portion of the urine (say 5 c.c.) ten 

 times; that is, add to it nine times its volume of distilled water (45 c.c.) 

 from a burette. Place some pure nitric acid in a test-tube with a 

 pipette, taking care not to wet the sides of the test-tube with the 

 acid. Now run on to the surface of the nitric acid some of the 

 diluted urine, and note the interval that elapses before formation 

 of the white ring. If it is more than three minutes, the diluted urine 

 contains less than i part in 30,000, and the undiluted urine less 

 than i part in 3,000 (i.e., less than '033 per cent.) of coagulable 

 proteid, and the experiment must be repeated with urine diluted 

 to a smaller extent. If the ring appears after a shorter interval 

 than three minutes, the diluted urine contains more than i part in 

 30,000 (the original urine more than '033 per cent.), and must be 

 further diluted. Fill a burette with the diluted urine. Run i c.c. of 

 it into a test-tube and add 9 c.c. of distilled water. Repeat the 

 test with this second dilution. If the ring appears at a longer 

 interval than three minutes, the twice-diluted urine contains less than 

 i part of albumin in 30,000, and the original undiluted urine less 

 than i part in 300, i.e., less than 0-33 per cent. So far, then, 

 we have found, let us suppose, that the proportion of albumin in the 

 original urine lies between 0*033 an( ^ '33 P er cent. Now run i c.c. 

 of the urine of the first dilution (the urine diluted ten times) into 

 a test-tube, and add 4 c.c. of distilled water, i.e., dilute again five 

 times. If this gives the white ring in Heller's test in three minutes, 



the original urine will contain i part of albumin in > *<% i n 



10 x 5 



600 parts, or 0*16 per cent. If the interval is longer or shorter than 

 three minutes, the urine of the first dilution (i to 10) must be diluted 

 less or more than five times until the interval amounts to about 

 three minutes. The total dilution corresponding to a percentage of 

 0*0033 of albumin is thus known, and the percentage in the undiluted 

 urine can be easily calculated. 



13. Sugar (i) Qualitative Tests (a) Trommer's Test. See p. 23. 

 It is to be remarked that some substances present in small amount 

 in normal urine reduce cupric sulphate, e.g., uric acid (present as 

 4irates) and kreatinin, but although a normal urine may thus de- 



