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PHYSIOLOGY AND TOXICOLOGY 



The same little apparatus was also employed in the following experiments on 

 the effects of heat on the venom. In each case the tube was charged, sealed at 

 one end, and placed in water of the required temperature. In sustaining the 

 standard of heat, it occasionally happened that the temperature rose one or two 

 degrees too high, but this in no way affected the general result or its value. 

 When the higher temperatures were used, the finger was sometimes placed on the 

 open end of the tube, both to prevent the bubble of air below the venom from en- 

 larging in the heat so as to expel the fluid above it, and also for the purpose of 

 limiting evaporation. 



The results attained are expressed in the following table : — 



The results exhibited in the table, seemed to show that, while freezing did not 

 alter the powers of the venom, it lost its toxicological vitality at a temperature of 

 212° F. 



Upon re-examining this question at a later date, and Avith larger quantities of 

 venom, I came to the conclusion that I had been mistaken, and that the most pro- 

 longed boiling was inadequate to destroy the virulence of the venom. The error 

 into which I previously fell was due to the following causes : — 



I have shown that after boiling, the active portions of the poison were the super- 

 natant fluids, and not the coagulum. Now, when the amount employed was small, 

 and the boiling was conducted in tubes of moderate calibre, the quantity of fluid 

 surrounding the coagulum was in proportion minute. The larger part of it, there- 

 fore, clung to the tube, and was practically lost. That which adhered to the pre- 

 cipitate proved insufficient, in most cases, to destroy life, although some of the ani- 

 mals suffered from its use. 



In August, 1860, a year after the first examination of this point, I carefully 

 studied it anew. Not less than four drops of venom were employed in each case, 

 and the process of boiling was varied in duration, so that in some cases it was 

 continued for five minutes, in others for half an hour or more. Thus prepared, the 



