328 Amino-Acid Nitrogen in Blood 
TABLE I.* 
Recovery af the Nitrogen of Amino-Acids. Amino-Acid Nitrogen per 10 
Ce. of Solution. 
Matera Acca of elt | 
gm. mg. 
YVOSHIOfe, see. he ts ho ee ee 0 1.67 
Sate Pehl vo tas J ag Bee Coe er ‘ei weroh ore 1.67 
A Lami py eh taicean, oF <0 Seneee Re ee 0 : 13.70 
in) RR eS ME NOIR iy Sta ea Us 2, 3, or 4 13.70 
Amino-acids from Gasein........ 15.0. 0 10.35 
< * SPR RRMA Rech gr fk Sug 2 or 4 10.35 
* For the pure amino-acids I am indebted to Professor M. Kumagawa 
and his staff. Amino-acids from casein were obtained by hydrolyzing 
pure casein by boiling with 25 per cent hydrochloric acid for 30 hours. 
The liquid was neutralized with sodium hydroxide and filtered. The 
filtrate was treated with animal charcoal and filtered. After the solu- 
tion was found entirely free from protein, it was diluted to a convenient 
concentration of amino-acid nitrogen and treated by the Van Slyke method. 
As ammonia is found in the hydrolysis of casein, it was removed before 
the determination of the amino-acid nitrogen. 
are useless, because by heat (half an hour in a water bath) the 
nitrogen of normal blood filtrates may be increased to twice the 
real value.” No figures are offered.confirming this statement. 
Bock attempted a comparison between the direct trichloroacetic 
acid precipitation and the heat coagulation followed by the tri- 
chloroacetic acid precipitation, and has shown that the latter 
procedure gives even slightly lower results than the former. As 
kaolin could not be used directly for the blood protein precipitant, 
a comparison between the direct kaolin precipitation and the 
heat coagulation followed by kaolin precipitation on blood plasma 
was carried out. Direct kaolin precipitation was carried out as 
follows: The blood plasma, diluted ten to twelve times with dis- 
tilled water, was acidified with 2 to 4 cc. of glacial acetic acid, 
40 gm. of kaolin per 100 ce. of diluted solution were added, then 
the mixture was filtered with suction. After the filtrate was 
found entirely free from protein, an aliquot was taken and evap- 
orated to a small volume. ' For the determination of amino-acids, 
urea and ammonia were removed by usual procedure. ‘Tables 
II and III show no substantial difference between the procedures. 
