532 



PHYSIOLOGICAL CHEMISTRY 



filter paper, wash the precipitated protein, in turn, with hot water, 95 per cent 

 alcohol, and with ether, and dry the paper and precipitate, to constant weight, in 

 an air-bath at noC. Subtract the weight of the filter paper from the combined 

 weight of the paper and precipitate and calculate the percentage of protein in the 

 urine specimen. 



Calculation. To determine the percentage of protein present hi the urine 

 under examination, multiply the weight of the precipitate, ex- 

 pressed in grams, by 2. 



Interpretation. The amount of albumin occurring 

 in the urine is not necessarily an index of the severity 

 or type of the disorder giving rise to it. Hence no sig- 

 nificant figures can be given. Normal human urine 

 probably contains a trace of albumin which is too slight 

 to be detected or determined by the usual procedures. 

 The determination of albumin may be of assistance in 

 following the course of kidney disturbances, but the re- 

 sults can be interpreted only in the light of other clinical 

 findings. 



2. Esbach's Method. This method depends upon the pre- 

 cipitation of protein by Esbach's reagent 1 and the apparatus 

 used in the estimation is Esbach's albuminometer (Fig. 167). 

 In making a determination fill the albuminometer to the 

 point U with urine, then introduce the reagent until the 

 point R is reached. Now stopper the tube, invert it slowly 

 several times in order to insure the thorough mixing of the 

 fluids, and stand the tube aside for 24 hours. Creatinine, resin, 

 acids, etc., are precipitated in this method, and for this and 

 other reasons it is not as accurate as the coagulation method. 

 It is, however, extensively used clinically. According to Sahli 2 

 the method is "accurate approximately to one part per 1000," 

 whereas Pfeiffer 3 claims it is not accurate for less than one- 

 half or for more than five parts per 1000. 



Calculation. The graduations on the albuminometer indi- 

 Fig. 167. cate grams of protein per liter of urine. Thus, if the protein 

 ESBACH'S AUBU- precipitate is level with the figure 3 of the graduated scale, this 

 denotes that the urine examined contains 3 grams of protein to 

 the liter. To express the amount of protein in per cent simply move the deci- 

 mal point one place to the left. In the case under consideration the urine 

 contains 0.3 per cent protein. 



Interpretation. See above. 



3. Kwilecki's Modification of Esbach's Method. 4 Add 10 drops of a 10 per 

 cent solution of FeCla to the acid urine before introducing the Esbach's reagent. 



1 Esbach's reagent is prepared by dissolving 10 grams of picric acid and 20 grams of 

 citric acid in i liter of water. 



2 Sahli: Lehrbuch d. klin. Untersuchungs-Methoden, 5th Aufl., 1909. 



3 Pfeiffer: Berl. klin. Woch., 49, 114, 1912. 



4 Kwilecki: Munch med. Woch., 56, p. 1330. 



