788 URINE. 



milligrams per liter. Frequently traces of a substance similar to a 

 nucleoalbumin, which is easily mistaken for mucin, and whose nature 

 will be treated of later, appears in the urine. In diseased conditions 

 proteid occurs in the urine in a variety of cases. The albuminous bodies 

 which most often occur are serglobulin and seralbumin. Proteoses (or 

 peptones) are also sometimes present. The quantity of proteid 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. Cases are known, however, where it 

 was even more than 80 p. m. 



Among the many reactions proposed for the detection of proteid 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 1/10 vol. of a saturated common-salt solution 

 before boiling; then heat to the boiling-point, and if no precipitation, 

 cloudiness, or opalescence appears, the urine in question contains no 

 coagulable proteid, but it may contain proteoses or peptones. If a pre- 

 cipitate is produced on boiling, this may consist of proteid, or of earthy 

 phosphates, 1 or of both. The monohydrogen calcium phosphate decom- 

 poses on boiling, and the normal phosphate may separate out. The 

 proper amount of acid is now added to the urine, so as to prevent any 

 mistake caused by the presence of earthy phosphates, and to give a better 

 and more flocculent precipitate of the proteid. If acetic acid is used 

 for this, then add 1-3 drops of a 25 per cent acid to each 10 cc. of the 

 urine and boil after the addition of each drop. On using nitric acid, 

 add 1-2 drops of the 25 per cent acid to each cubic centimeter of the 

 boiling-hot urine. 



On using acetic acid, when the quantity of proteid is very small, 

 and especially when the urine was originally alkaline, the proteid may 

 sometimes remain in solution on the addition of the above quantity of 

 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 a 

 proteid 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 combina- 

 tion between it and the proteid is formed which is soluble on boiling and 

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

 large quantity of nitric acid, as suggested above, must be added, but in 

 this case a small part of the proteid is liable to be dissolved by the excess 

 of the nitric acid. When the acid is added after boiling, 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 proteid. 



1 In regard to the cause of the phosphate precipitation on boiling the urine, see 

 Malfatti, Hofmeister's Beitrage, 8. 



