THE ALBUMINS. 303 



is probably of albuminous character. Nothing further, however, is 

 known of the substance. In rare instances I have found it present 

 in large amounts. 



As nucleo-albumins, when present beyond traces, can simulate 

 the true albumin reaction, it is well to dilute the urine with water 

 and to examine again when its presence is suspected. If then the 

 reaction is more pronounced than before, the precipitate may, in part 

 at least, be referable to this source. This possibility should be con- 

 sidered if the urine contains an increased number of morphological 

 elements, and if the reaction is slight. Other tests should then also 

 be employed. 



Albumoses, if present beyond traces, also react with nitric acid, 

 but it is to be noted that in such cases the precipitate disappears on 

 heating and reappears on cooling, while the liquid at the same time 

 assumes an intensely yellow color. Should a mixed albuminuria 

 exist i. e., should albumoses and albumin be present simultane- 

 ously the clearing of the urine is only partial. 



As nitric acid also precipitates certain resins which may have 

 been administered for medicinal purposes, it is at times necessary to 

 eliminate this possibility of error. Their presence is indicated if 

 the precipitate disappears on shaking the mixture with ether. 



The Boiling Test. The test is best conducted in the following 

 modification : A few cubic centimeters of urine are tested with one- 

 sixth of its volume of a saturated solution of common salt, after 

 having rendered it distinctly acid by the addition of a drop or two 

 of a 25 per cent, solution of acetic acid. The mixture is then 

 boiled, when in the presence of coagulable albumins the liquid 

 becomes turbid, and on standing a flocculent precipitate gathers at 

 the bottom of the tube. The turbidity may, however, at times be 

 due to a precipitation of earthy phosphates. To distinguish between 

 the two, one or two drops of a 25 per cent, solution of nitric acid 

 are now added for every 1 c.c. of the urine. The earthy phosphates 

 are thus dissolved, while the precipitate of albumin remains un- 

 affected. The test in this modification is very satisfactory and 

 delicate. 



If the albumin of Bence Jones should be present, coagulation 

 occurs at a temperature of 50 C. already, but it will be noted 

 that the precipitate disappears on subsequent boiling and reappears 

 on cooling. 



The common albumoses, as well as nucleo-albumin, are not 

 thrown down. The presence of the former may be inferred if 

 after the addition of the acid and subsequent cooling a white pre- 

 cipitate is formed, which dissolves upon the application of heat and 

 reappears on cooling. 



The Potassium Ferrocyanide Test. A few cubic centimeters of 

 urine are strongly acidified with acetic acid, and treated with a 

 10 per cent, solution of potassium ferrocyanide drop by drop, when 

 in the presence of albumin a precipitation occurs which varies 



