184 



H. B. TAYLOR. 



In the following table (Table VII) are some of the deter- 

 minations made on mixtures of the standard solutions, 

 giving the E.M.F. and the value for the H ion calculated 

 from this figure. The numbers in the last column are the 

 negative indices to which ten is raised, i.e. 4*43, means 



10 -443 



Table VII. 





Sol 



ution. 







E.M.F. 



H. ion. 



15 cc. 



Hcl. 



+ 35 cc 



. citrate . 



.. '5932 



4-43 



10 



n 



+ 40 



ii 





.. '6049 



4*63 



5 



»» 



+ 45 



ii 





.. -6159 



4'82 







n 



+ 50 



ii 





.. '6223 



4*93 



5 cc. 



NaOH 



+ 45 



ii 





.. *6336 



5*13 



10 



ii 



+ 40 



ii 





.. '6453 



5*33 



15 



ii 



+ 35 



ii 





.. *6600 



5'58 



20 



ii 



+ 30 



ii 





.. '6820 



5-96 



10 cc. 



sec. phos. 



+ 40 cc. 



prim 



phos 



. -6912 



6*18 



15 



ii 



+ 35 



*i 





•7082 



6*42 



25 



ii 



+ 25 



ii 





•7285 



6*77 



30 



ii 



+ 20 



ii 





•7405 



6*98 



In regard to the determinations of H ion concentrations 

 in milk, it might be doubted whether the fat and other 

 coustituents interfered with the method. To ensure that 

 the correct result is obtained when E.M.F. determinations 

 are made on the milk, the H ion concentrations at various 

 dilutions were obtained, and the H ion values plotted 

 against the logarithms of the concentrations. This was 

 done both with the fresh milk, and with milk where the H 

 ion had reached its maximum value. As will be seen from 

 figures 1 and 2, both the graphs are straight lines, passing 

 through the values obtained for the undiluted milk, show- 

 ing that the correct result is obtained by determinations 

 made on the pure milk, that the H ion is proportional to the 

 logarithm of the concentration and that fat in the milk has 

 no effect on H ion determinations. 



