JOHN H, NORTHROP 



729 



In other words, the "concentration" as determined by the hydrogen 

 electrode is the effective concentration for the present reaction. 

 In a very recent paper Schreiner^^ has suggested the use of a special 

 "catalysis-coefficient" to express the relation of the apparent hydro- 

 gen ion concentration, as determined by catalysis experiments, to 

 the total acid concentration. Schreiner states that this coefficient 

 is equal to the reciprocal of the conductivity ratio (corrected for 



TABLE V. 



Hydrolysis of 2.5 Per Cent Gelatin in Strong Acid at 40° C 



E.M.F. 



[5.5] 

 5.4 

 2.0 

 3.6 

 1.6 



2.7 



2.10 



0.90 



1.50 

 0.84 

 0.85 

 0.89 



0.40 

 0.72 



Ch 

 Conduc- 

 tivity. 



1.97 



1.88 

 1.57 

 1.75 

 1.40 



1.48 

 1.40 

 1.00 



1.06 

 0.80 

 0.80 

 0.80 



0.50 

 0.60 



Velocity. 



800 

 790 

 300 

 600 

 180 



380 

 [400] 

 130 



220 

 142 

 130 

 [160] 



60 

 110 



Kn = average. 



Velocity 



Cjj (E.M.F.) 



[130] 

 146 

 151 

 167 



[125] 



140 

 [190] 

 146 



140 

 170 

 160 



[180] 



150 

 155 



152 



Velocity 



Cg (conductivity) 



400 

 400 

 200 

 340 

 130 



250 



[280] 

 130 



210 

 178 

 162 



[200] 



120 



185 



viscosity), and he is able by its use to calculate quite closely the 

 velocity of hydrolysis of methyl and ethyl acetate in concentrated 

 acid or acid-salt mixtures. It seems unnecessary to introduce such 

 a coefficient in order to account for the results of the experim.ents 

 reported here, since it is possible to calculate the velocity, within 

 the rather large experimental error, by means of the activity coeffi- 

 cient alone. 



Schreiner, E., Z. anorg. u. allg. Chem., 1921, cxvi, 102. 



