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II. Tranjlation of an EJfay written by the AIM Fontana, on the 
American Poifon called Ticimas. See page 163. 
T HE experiments which I made at Paris during two years 
on the poifon of the viper, and which are the fequel of 
many others on the fame fubjedt, publifhed in Italy ten years 
before, have enabled me to pronounce with fafety on the nature 
and properties of that poifon. The unexpended and important 
cffedls which I obferved on the application of the poifon of that 
animal to the bodies of living creatures, have led me to new dis- 
coveries in animal phyfics ; and thefe difcoveries have gradually 
led me to doubt of fome certain medical theories, either not fur- 
ficiently proved, or too generally applied by pradtitioners. 
From that time I have been defirous of extending my re- 
fearches to other poifons ; and, if it had been poffible, I could 
have wilhed to examine fome of the moft adtive vegetable 
poifons. I had imagined, the animal poifons were like the 
poifon of the viper, which freely diffufes itfelf through the 
body of an animal when applied to a wound, but is not 
increafed thereby in the manner in which the poifon which 
produces the fmali pox, or the canine madnefs, is augmented : 
I fay, I conceived, that thefe poifons might have much analogy 
to one another, and that they might add in the fame manner, 
and upon the fame parts of animals. O11 the other hand, I did 
not dare to conjecture any thing concerning the operation of ve- 
getable poifons, which I had not yet examined ; nor did I think 
that any thing could fafely be advanced concerning the adtion. 
of them, even after the inftrudtions derived from the beft wri- 
ters on them. Their maimer of experimenting was very dif- 
ferent from that which I had ufed in examining the poifon of the 
viper, and their inferences appeared too vague and uncertain. 
Being arrived at London, however, 1 had it eafily in my power 
to fatisfy my defires on this head. Dr. hererden, an eminent 
V oLt LXX. B phyfician 
