212 Professor Svante Arrhenius [June 9, 



Spontaneous Destruction op Dissolved Tetanolysin at 49*8° C. 



t (minutes) c, observed c, calculated 



100-0 100-0 



20 80-0 80-6 



40 61-1 64-8 



60 52-1 52-3 



80 46-3 42-1 



120 26-8 26-7 



180 14-6 14-3 



Tetanolysin is a very strong poison secreted by tetanus-bacilli, 

 whereby they cause lock-jaw (tetanus). The close agreement between 

 the calculated and the observed figures of its strength c indicates that 

 the simple law, which says that 50 per cent, of the poison is destroyed 

 in about 64 minutes, 75 per cent, in double the time, 128 minutes, and 

 87 • 5 per cent, in the threefold time, 192 minutes, is very nearly exact. 

 That is the law of monomolecular reactions, when every reacting 

 molecule^ — here every molecule of the poison — is decomposed inde- 

 pendently of every other molecule in the solution, except perhaps of 

 the water itself. It is necessary to keep the temperature very 

 accurately constant, because it has an extremely great influence on 

 the rate of decomposition. Thus, for instance, this rate is 1(5 '7 times 

 greater at 53 •5'' than at 49*8°, i.e. the tetanolysin loses its half 

 strength in a little less than 4 minutes at 53 • 5°. An increase of as 

 little as 0*1° C. increases the rate of decomposition by 8 per cent. 

 An increase of 1° accelerates the decomposition 2 '14 times. 



In general, the stability of these bacterial poisons is largely 

 influenced by temperature. 



As Madsen has remarked, this property may be useful for the 

 animal body, which generally reacts against these poisons by an in- 

 creased temperature, i.e. fever. 



An addition of alkali or acid mostly accelerates the process in a 

 high degree. Many of these preparations contain a little alkali in 

 their original state. Then an addition of acid increases their stability. 

 In such cases even diluted solutions may be more stable than more 

 concentrated ones. 



But, in general, these preparations, and even the antigenes, are 

 most stable in the form of dry powder, and are decomposed the more 

 rapidly the higher the dilution. This is the case, for instance, with 

 rennet, as is seen from the following figures of Madseii and Walbuui, 

 valid for 46° C. :— 



Concentration p.c. 7 5 8 2 1 0-5 0-25 0-125 0-068 



Velocity of Iq-OOS? 0-0049 0-0154 0-0212 0-028 0-032 0-039 0-060 0-073 

 decomposition/ 



Dry rennet is very much more stable : it is not decomposed 

 in a sensible degree at temperatures below 100° (J. ; at 158" C. the 

 velocity of decomposition is only 0*071. The higher stability in 

 higher concentrations probably depends on the formation of com- 



