134 BIO-CHEMICAL JOURNAL 



Here again variation with dilution. Greater dilution impracticable 

 owing to difficulty of filtration. 



Series IV. Sodium sulphate method. Same serum and peptone 

 solution as in Scries III. 



25 c.c. serum added to 5 c.c. peptone solution. 



N 

 Total N = 400 c.c. H 2 SO*. 



' ' IO 



N 

 Coagulable N, (Expt. I) = 4357 H 4 SO 4 . 



(Expt. II) = 4347 -^-H'SO*. 



N N 



Residual N = (490-0 - 435'2)-^-H 2 SO* = 54-8 H^SO*. 



N in peptone solution alone = 47*4 H 2 SO 4 . 



N 



Hence residual N in serum = 7*1 c.c.-^~H 2 SO* ; a number which sub- 

 sequent experiments shows to be a trifle low. 



Series V. Sodium sulphate method. Determination of N in 

 coagulum. 



15 c.c. of serum. Coagulable N = I i6-2-^-H 8 SO*. 



15 c.c. of serum + 10 c.c. 10 per cent. Witte's peptone. 



N 

 Coagulable N = 118-5 H 2 SO*. 



Here, in spite of large amount of residual N from the peptone, very 

 little is carried down with the coagulum. 



The method gives, therefore, accurate results, and can be made 

 independent of the concentration of a solution, as a dried powder is 

 always used for coagulation. 



REFERENCES 



1. Haslam, Journal of Physiology, 32, p. 267, 1905. 



2. Pinkus, Journal of Physiology, 27, p 57, 1901. 



3. Hedin, Journal of Physiology, 30, p 195, 1903. 



PART III 



THE DISTRIBUTION OF NITROGEN IN THE SERUM, LIVER, AND 



Mucous MEMBRANE OF THE SMALL INTESTINE DURING 



DIGESTION OF FOOD AND DURING A FAST 



The method of research has been already described. 



The liver was put through a fine mincing machine before weighing. 



