THE CHEMICAL STUDY OF SNAKE-VENOMS 161 
All venoms are not equally affected by heat. The venoms of 
CoLUBRIDÆ (Naja, Bungarus, Hoplocephalus, Pseudechis) and those 
of the HYDROPHIIDÆ 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 ViIPERIDm (Lachesis, Crotalus, Vipera) are 
much less resistant. By heating to the coagulating point of 
albumin, 2.e., to about 70° C., their toxic properties become 
attenuated, and they are entirely suppressed between 80° and 85° C. 
Lachesis-venoms 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- 
BRIDE, 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 VIPERIDÆ, 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 CoLUBRIDZ and VIPERIDÆ. ‘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 COLUBRID ; 
et 
