CH. X.] NON-PROTEIN NITROGEN. 263 



down into G with a jet of water. Disconnect the pump and then 

 the rubber connexion of F to the condenser. Remove the stopper 

 of G with the tubes and wash down the interior and exterior of F 

 into G. Fit the tube shewn in fig. 35 to G and titrate with 

 standard CO 2 -free soda (which should be about 0-04 N.). 



Calculation and Example (see p. 323). 



Soda was 0-032 N. 



Acid was 0-029 N. (i cc. = 0-029 x 14 = 0-406 mg. N.). 



Soda required for titration was 7-61 cc. = 76-1 x =8-40 cc. of the acid 2 



So acid neutralised by the Nitrogen in 20 cc. filtrate was 10 - 8-4 = 1-6 cc. 



So non-protein N. in 2 cc. blood = 1-6 x 0-406 = 0-65 mg. 



Blank determination = 0-02 mg. N. 



So non-protein N. in 2 cc. blood = 0-63 mg. 



Non -protein N. in 100 cc. = 31-5 mg. 



NOTES. i. Folin and Denis (Journ. Biol. Chtm., xxvi., p. 491) introduced, 

 the method of precipitating the proteins with metaphosphoric acid. They 

 estimate the nitrogen by direct Nesslerisation after incinerating with a mixture 

 of sulphuric and phosphoric acids. The author has not been successful in 

 repeating their results, being troubled with the rapid formation of a cloud after 

 adding Nessler's reagent. Under these circumstances the above method of 

 distillation of the ammonia has been elaborated. 



2. The amount of non-protein nitrogen in normal human blood seems 

 to vary between 30 and 50 mgms. per 100 cc. It is increased in certain types 

 of nephritis and in severe hepatic disease. 



