386 DISEASES OF THE KIDNEYS 



a well defined white ring forms, the depth of which depends 

 upon the amount of albumin present. 



The boiling point may also be used. Take a few cubic 

 centimeters of urine in a test-tube and heat to boiling, acidu- 

 late by adding 5 to 10 drops of concentrated nitric acid. A 

 precipitate which has been formed by earthy phosphates or 

 carbonates will then dissolve, but one due to coagulated 

 albumin remains. 



The metaphosphoric acid test is made by adding an aque- 

 ous solution of metaphosphoric acid to the urine. The urine 

 becomes cloudy in case albumin is present. 



The acetic acid-ferrocyanid of potassium test is made by 

 adding 2 per cent, of acetic acid to the urine and then a 

 5 per cent, solution of ferrocyanid of potassium, the latter 

 drop by drop avoiding an excess. If albumin is present a 

 decided turbidity or flocculent precipitate appears. 



The quantitative determination of albumin is made with 

 Esbach's albuminometer. Acidulated urine is filled into the 

 sign U, the reagent up to R (1 part of picric acid, 2 parts of 

 citric acid, and 100 parts distilled water), the tube is closed 

 with a rubber stopper and slowly turned over several times 

 without shaking; let stand at room temperature for twenty- 

 four hours, the precipitate has settled and may be read off. 

 The figure indicates the proportion of albumin in grams pro 

 mille. Urine containing a large percentage of albumin must 

 be first diluted with water and the indicated figure must then 

 be multiplied with the figure of the dilution to obtain the 

 exact amount of albumin present. 



When it has been demonstrated that albumin is present 

 in the urine, then it must be determined whether the albumin 

 originates from the kidneys, from the urinary passages, or 

 from the nearby genital organs. If the urinary sediment 

 contains no organic form elements, or form elements derived 

 from the kidneys, and if the presence of dissolved coloring 

 matter of the blood may be excluded, then it is positive that 

 it is renal albuminuria. If there is a large amount of organic 

 sediment then it is not likely to be renal albuminuria. In 

 some cases it is possible to have a mixture, coming from the 

 kidneys and also from other parts of the urinary system. 



