32 VELOCITY OF REACTIONS 



the velocity of reaction in this case, but also the 

 acidity of the solution, as is seen from the following 

 figures, borrowed from SORENSEN. A series of ex- 

 periments was carried out with invertase and a small 

 addition of sulphuric acid at 30 C. As independent 

 variable is taken the hydrogen -ion concentration. 

 As is seen from those figures a very flat maximum 

 is obtained at the hydrogen concentration 0-0000372. 



Influence of Acidity on Velocity of Reaction. 

 Inversion of Cane-Sugar (at 30 C.). 



Cone, of H-ions . . 3-icr 4 io~ 4 3-io~ 5 io~ 5 3-io~ 6 io~ 6 3-10-* 

 Vel. of Reaction -i o 4 . 77 82 83 81 78 73 64 



Decomposition of Tetanolysin (at 50 C.). 



Normality NaOH . . . 0-02 o-oi 0-005 o-o-oi -0-02 : H 2 SO 4 

 Velocity of Reaction -i o 4 .112 97 85 ^7 71 435 



Digestion by means of Pepsin (at 52 C.). 



Cone, of H-ions . . 0-17 iQ- 1 6-io~ 2 2-io~ 2 5-io~ 3 8-io~ 5 

 Digested quantity/ i hour 8-5 9-3 12-3 15*2 15-0 10-8 

 in mgms. after \49hours ... 30-3 j/-j 30-9 28-1 16-1 



50 per cent Decomposition of Hydrogen Peroxide with Colloidal 



Platinum (at 25 C.). 



Cone, of NaOH . . o 0-002 0-008 0-031 0-125 0-25 0-5 i-o 

 Time in mins. . . 255 34 25 22 34 70 162 520 



For comparison similar figures for three other 

 processes are given : the first concerns the influence 

 of bases (NaOH) or acids (H 2 SO 4 , indicated by a- 

 sign) on the rate of decomposition of tetanolysin at 

 50 C., according to some measurements of my own. 

 The addition of small quantities of both bases and 

 of acids increases the decomposition in a marked 

 degree. 



