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of cobra-poison. Thus half a cubic centimetre of dilute 

 solution of cobra-poison, containing half a milligramme 

 of poison, killed a small fowl in thirty-three minutes ; 

 whereas after the solution had been boiled, it took forty- 

 seven minutes to kill a fowl of the same size. 



Moreover, when a solution of cobra-poison, contain- 

 ing 2'5 milligrammes to the cubic centimetre was heated 

 to 100° C. "6 milligramme of the poison killed a fowl 

 in sixty-four minutes, whereas when the solution which 

 was heated only contained I'SS milligrammes to the 

 cubic centimetre, "6 milligramme of the poison required 

 no less than 111 minutes to cause death. This shows- 

 clearly with how much greater ease heat destroys dilute 

 solutions than concentrated ones. 



We see, then, that a temperature of J 00° C. has a 

 distinct effect in lessening the strength of a solution of 

 cobra-poison, but that a very great heat continued for 

 a very long time is required to completely destroy the 

 properties of a concentrated solution. If cobra-poison 

 consisted of a collection of " germs," it is, of course, 

 conceivable that the " germs " might resist great heat,, 

 but it is not credible that one collection of them should 

 be destroyed by heating for half an hour to 106° 

 (Experiment V.), whilst another should resist for more 

 than an hour a heat of 1 07° C. (Experiments II. and 

 III.) Tho heat that would destroy one germ would 

 destroy all, and the solution, instead of gratlually 

 becoming weaker, would at once lose its virulence with 



