which incites the Muscles of Animals to contract. 251 
Before I dismiss this part of my subject I may mention, 
that, being in possession of a method to determine what 
substances are capable, along with metals, of exciting the 
influence, I made several experiments for the purpose of as- 
certaining this point. I found, in consequence, that all fluid 
bodies, except mercury, that are good conductors of electri- 
city, all those at least which I tried, can with the aid of me- 
tals produce it. The bodies I tried, beside water, were alcohol, 
vinegar, and the mineral acids ; the last both in their concen- 
trated states, and when diluted with various portions of water. 
Alcohol, however, operated feebly. On the other hand, no 
fluid, which is a non-conductor of electricity, would assist in 
its production : those upon which the experiment was made 
were the fat and essential oils. Ether, from its similarity to 
alcohol, I expected would also have concurred in the excite- 
ment of the influence, but it did not ; neither would it con- 
duct the influence when excited by any other means. I may 
remark, however, that the ether I employed had been pre- 
pared with great care ; other ether, therefore, less accurately 
made, may possibly be found to contribute to the excitement 
of the influence, either from the undecomposed alcohol, or 
naked acid, it may contain. 
Having thus given an answer to the first question, I pro- 
ceed to the discussion of the second. 
It has hitherto been maintained by every author, whose 
works I have read upon the subject of Mr. Galvan fs experi- 
ments, and by every person with whom I have conversed re- 
specting it, that metals are the only substances capable, by 
their application to parts of animals, of exciting the influ- 
ence, which in those experiments occasions the muscles to 
