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"When a coating of lead, tin, or copper, 
was fubftituted for that of filver, which en¬ 
veloped the nerves, or that of the mufcles, 
the movements were very violent. One 
might obferve the following gradation in 
the aCtion of metals.—Lead produced the 
mo ft violent movements, next tin, and after 
that copper. In proportion as the frog loft its 
vitality, the metals likewife loft the faculty 
of determining the paffage of the electri¬ 
cal fluid in the animal. Lead, tin, and 
zinc retained this property the longeft. 
A piece of glazier’s lead employed for 
both coatings, with a conductor of the 
fame metal, produced nothing. But when 
lead of different qualities was made ufe of, 
as, for inftance, glaziers lead and that of 
affay, an exciter of one of thefe metals 
produced remarkable effects. When thefe 
two different leads ceafed to produce any 
appearance of contraction, by fubftituting 
for one of the coatings, another of filver, 
gold, 
