[ x 5 8 ] 
through the bent tube into the bottle A, and filled it 
almofi: intirely full. 
The experiment was repeated again in the fame 
manner, except that I took away the bottle D, and 
let out fome of the water of the cittern : fo that the 
end of the bent tube was out of water. As foon as 
the effervelcence began, the vapours iflued vifibly out 
of the bent tube ; but they were not at all inflam- 
mable, as appeared by applying a piece of lighted 
paper to the end of the tube. A fmall empty phial 
was then inverted over the end of the bent tube, fo 
that the mouth of the phial was immerfed in the water, 
the end of the tube being within the body of the phial 
and out of water. The common air was by degrees 
expelled out of the phial, and its room occupied by the 
vapours ; after which, having chanced to fhake the 
inverted phial a little, the water fuddenly rufhed in, 
and filled it almofi: full ; from thence it palled through 
the bent tube into the bottle A, and filled it quite full. 
It appears likely from hence that copper, by folution 
in the marine acid, produces an elafiic fluid, which 
retains its elafticity as long as there is a barrier of com- 
. mon air between it and the water, but which imme- 
diately lofes its elafticity, as foon as it comes in contadt 
with the water. In the firfi experiment, as long as 
any confiderable quantity of common air was left in 
the bottle containing the copper and acid, the vapours, 
which pafled through the bent tube, mufthave contain- 
ed a good deal of common air. As foon therefore as 
any part of thefe vapours came to the farther end of 
the bent tube, where they were in contadf with the 
water, that part of them, which confifted of the air 
from copper, would be immediately condenfed, leav- 
4 in g 
