552 PHYSIOLOGICAL CHEMISTRY 



the other is added the albuminous urine i c.c. at a time (by means of an Ostwald 

 pipette) until the turbidity obtained seems to be reasonably near that of the 

 standard. The two flasks are then filled up to the mark with water, cautiously 

 inverted a few times to secure mixing, and are then ready for the quantitative 

 comparison just as in colorimetric work. The standard must invariably be read 

 against itself. The standard 1 containing 10 mg. of protein is set at 20 mm. The 

 unknown must not read less than 10 nor more than 30. 



Calculation. Dividing 200 by the product of the reading of the unknown and 

 the number of cubic centimeters of urine taken gives the albumin in milligrams per 

 cubic centimeter of urine. The albuminous suspensions must not be shaken but 

 mixed very carefully. The method is fairly accurate and requires but a few minutes 

 if a standard solution is at hand. The method is not applicable to urines deeply 

 colored with blood or bile but may be used for albuminous fluids other than urine 

 if such fluids are not highly pigmented. It must be borne in mind that different 

 proteins, as serum albumin and serum globulin, may give markedly different degrees 

 of turbidity under the same conditions. 2 



Interpretation. See page 551. 



Bence-Jones Protein. Method of Folin and Denis. 3 Principle. A known 

 volume of urine is heated at 6o ? the coagulated Bence-Jones protein is then 

 thrown down by centrifugation, washed with 50 per cent, alcohol, dried and 

 weighed. 



Procedure. Place 10 c.c. of the urine containing Bence-Jones protein in a pre- 

 viously weighed, conical centrifuge tube, add i c.c. of 5 per cent, acetic acid, 4 

 and allow to stand overnight 6 in a water bath at 60 C. The next morning remove 

 the tube from the bath, centrifuge for a few minutes and pour off the supernatant 

 liquid. Stir the sediment well with about 10 c.c. of 50 per cent, alcohol, centrifuge, 

 pour off the a cohol, dry at iooC. to constant weight, cool, and weigh. 



Calculation. Subtract the weight of the empty tube from that of the tube and 

 protein to obtain the weight of Bence-Jones protein contained in 10 c.c. of urine. 

 Calculate, from this figure, the percentage and 24-hour output. 



Interpretation. For a discussion of the significance of Bence-Jones proteinuria 

 see p. 442. 



Acetone Bodies 



Van Slyke's Methods. 6 Principle. The method is based on a com- 

 bination of Shaffer's oxidation of /Miydroxybutyric acid to acetone, 

 and Denige's precipitation of acetone as a basic mercuric sulphate 



1 Standard Albumin solution. Fresh blood serum free from hemoglobin is used. 

 25-35 c.c. of the serum are diluted with a 15 per cent solution of chemically pure sodium 

 chloride to about 1500 c.c. The solution is mixed and filtered. By means of nitrogen 

 determinations the protein content of the filtrate is determined (protein = NX 6.25) and 

 on the basis of the figure obtained the solution is diluted with 15 per cent sodium chloride 

 solution so that it contains 2 mg. of protein per cubic centimeter. It is best to saturate 

 the albumin solution with chloroform. The solution keeps for months. 



2 Marshall and Banks: Proceedings of the American Philosophical Society, 54, 176, 

 iQiS. 



a Folin and Denis: Jour. Biol. Chem., 18, 277, 1914. 



4 Taylor and Miller (Jour. Biol. Chem., 25, 281, 1916) suggest the use of only a trace of 

 acetic acid. 



6 From 6 P. M. until 8 A. M. is suggested as convenient. 

 Van Slyke : /owr. Biol. Chem., 32, 455, 1917. 



