THE URINE. 395 



albumin. Albumoses and peptones also sometimes occur. The 

 amount of albumin in the urine is in most cases less than 5 p. m., 

 rarely 10 p. m., and only very rarely does it amount to 50 p. m. or 

 over. 



Among the many reactions proposed for the detection of albu- 

 min in urine, the following are to be recommended : 



The Heat Test. Filter the urine and test its reaction. An acid 

 urine may, as a rule, be boiled without further treatment, and only 

 in especially acid urines is it necessary to first treat with a little 

 alkali. An alkaline urine is made neutral or faintly acid before 

 heating. If the urine is poor in salts, add -fa vol. of a saturated 

 common-salt solution before boiling; then heat to boiling point, 

 and if no precipitation, cloudiness, or opalescence appears, the 

 urine in question contains no coagulable albumin, but it may con- 

 tain albumoses or peptones. If a precipitate is produced on boil- 

 ing, this may consist of albumin, or of earthy phosphates, or of 

 both. The simple-acid calcium phosphate decomposes on boiling, 

 and normal phosphate may separate (STOKVIS, SALKOWSKI, OTT). 

 The proper amount of acid is now added to the urine, so as to pre- 

 vent any mistake caused by the presence of earthy phosphates, and 

 to give a better and more flocculent precipitate of the albumin. If 

 acetic acid is used for this, then add 1-2-3 drops of a 25$ acid to 

 each 10 c. c. of the urine, and boil after the addition of each drop. 

 On using nitric acid, add 1-2 drops of the 25$ acid to each c. c. of 

 the boiling-hot urine. 



On using acetic acid, when the amount of albumin is very small, 

 and especially when the urine was originally alkaline, the albumin 

 may sometimes remain in solution on the addition of the above 

 quantity of acetic acid. If, on the contrary, less acid is added, the 

 precipitate of calcium phosphate, which forms in amphoteric or 

 faintly-acid urines, is liable not to dissolve completely, and this 

 may cause it to be mistaken for an albumin precipitate. If nitric 

 acid is used for the heat test, the fact must not be overlooked that 

 after the addition of only a little acid a combination between it 

 and the albumin is formed which is soluble while boiling and 

 which is only precipitated by an excess of the acid. On this account 

 the large amount of nitric acid as suggested above must be added, 

 but in this case a small part of the albumin is liable to be dissolved 

 by the excess of the nitric acid. When the acid is added after boil- 

 ing, which is absolutely necessary, the liability of a mistake is not 

 so great. It is on these grounds that the heat test, although it 

 gives very good results in the hands of experts, is not recommended 

 to physicians as a positive test for albumin. 



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



