Determination of Urea. 



197 



five volumes of water are added and, after mixing, a comparison 

 is again made, the result this time being found by consulting Table 

 II. These tables cover a range from 10 to 100 mg. of urea N per 

 100 c.c. blood. 



TABLE II. 



Dilution, — 1 Vol. Solution : 7 Vols. Water : 1 Vol. Nessler's Solution. 





Mg. N 





Mg. N 





Mg. N 



Reading. 



per 



Reading. 



per 



Reading. 



per 





100 c.c. 





100 c.c. 





100 c.c. 



20 



31 











21 



32 



46 



62 



7i 



92 



22 



33 



47 



A. A 



64 



72 



94 



23 



34 



48 



65 



73 



95 



24 



30 



49 



00 



74 



96 



2 5 



37 



50 



07 



75 



97 



26 



38 



51 



68 



76 



98 



27 



39 



52 



70 



77 



99 



2o 



41 



53 



71 



78 



100 



29 



42 



54 



72 







3° 



43 



55 



73 







31 



44 



56 



74 







32 



46 



57 



76 







33 



47 



58 



77 







34 



48 



59 



78 







35 



49 



60 



79 







36 



50 



61 



80 







37 



51 



62 



82 







38 



53 



63 



83 







39 



54 



64 



84 







40 



55 



65 



85 







41 



56 



66 



86 







42 



58 



67 



88 







43 



59 



68 



89 







44 



60 



69 



90 







45 



61 



70 



91 







The tables represent the averages of many determinations 

 made on sunny and on cloudy days. This minimizes the slight 

 differences due to variations in intensity of light. 



Results obtained with this method agree closely with analyses 

 of the same specimens by the aeration method in which 2 c.c. of 

 blood were used. The micro method may be performed easily in 

 20-30 minutes with sufficient accuracy for clinical purposes. 



