THE CHEMICAL STUDY OF SNAKE-VENOMS 161 



All venoms are not equally affected by heat. The venoms of 

 CoLirBRiD;E (Naja, Bungarus, Hoplocephalus, Pseudechis) and those 

 of the Hydrophiid^ are entirely uninjured by temperatures 

 approaching 100° C, and even boiling for a short time. When 

 the boiling is prolonged, or when venoms are heated beyond 

 100° C, their toxic power at first diminishes, and then disappears 

 altogether. At 120° C. it is always destroyed. 



The venoms of ViPBRiDiE {Lachesis, Crotalus, Vipera) are 

 much less resistant. By heating to the coagulating point of 

 albumin, i.e., to about 70° C, their toxic properties become 

 attenuated, and they are entirely suppressed between 80° and 85° C. 

 Lacliesis-venoTD.s are the most sensitive ; their toxicity is lost 

 if they be heated beyond 65° C. 



On separating the coagulable albumins of the venoms of CoLU- 

 BRID^, by heating to 72° C, followed by filtration, we obtain a 

 perfectly limpid liquid, which is no longer injured by boiling, and 

 in which the toxic substance remains wholly in solution. The 

 albuminous precipitate, when separately collected and washed, 

 is no longer toxic. The clear liquid, after being filtered, is again 

 precipitated by absolute alcohol, and the precipitate, redissolved 

 in an equal quantity of water, is just as toxic as the original 

 filtered liquid. 



The venoms of Vipeeid^, when coagulated, by heating them 

 to a temperature of 72° C, and filtered, are almost always inert. 

 The albuminous coagula, if washed, redissolved in water, and 

 injected into the most sensitive animals, produce no harmful effect 

 whatever. 



The results of dialysis likewise differ when we experiment with 

 the venoms of Colubeid^ and Vipeeid^. The former pass 

 slowly through vegetable membranes, and with greater difficulty 

 through animal parchment. The latter do not dialyse. 



Filtration through porcelain (Chamberland candle F) does 

 not sensibly modify the toxicity of the venoms of Colubeid^ ; 

 11 



