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 000003/z. 



Influence of Acidity on Velocity of Reaction. 

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



Cone, of H-ions . . 3-io~ 4 10- 4 3-icr 5 io~ 5 3>io~ 6 io~ 6 3-icr 7 

 Vel. of Reaction -io 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 S0 4 

 Velocity of Reaction • 1 o 4 . 112 97 85 47 71 435 * 



Digestion by means of Pepsin (at 52 C). 



Cone, of H-ions . . 017 io -1 6-io~ 2 2-io- 2 5-io -3 8-io~ 5 

 Digested quantity/ 1 hour 8-5 9-3 . 12-3 75-2 15-0 io-8 



in mgms. after 1 49 hours ... 30*3 ji'j 30*9 28-1 i6«i 



50 per cent Decomposition of Hydrogen Peroxide with Colloidal 



Platinum (at 25 C. ). 



Cone, of NaOH . . o 0-002 o«oo8 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 S0 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. 



