made with the Doubler of Electricity. 273 
of its former charge; however, on trial it was found to be elec- 
trified negatively. This remarkable fact fully satisfied me that 
I had not deceived myself in the first experiment on the heap 
of leaves above mentioned. 
I repeated these experiments, with the doubler placed on 
various parts of the dunghill, without any remarkable variation 
in the results, except that the negative state of the exhaled 
vapour was stronger, and extended to a greater distance, in the 
depressed or hollow parts of the dung, where the vapour was 
less exposed to a moderate gale of wind that then prevailed, 
than on the open parts which lay full to it. I have reason to 
be of opinion, that the negative state of the vapour on the 
windward side of the dung did not reach so high as the re- 
volving plate of the doubler when turned up, so that in every 
revolution it must pass through electrified and neutral vapour, 
which required in those situations from thirty to forty revo- 
lutions to obtain a small charge. From this circumstance I 
am inclined to think that if £ doubler were made of very small 
dimensions, and placed in the neutral space between the two 
electric powers, it would be impossible to accumulate with it 
any spontaneous electricity. 
I was solicited to try the state of the air in the hot-hous« 
with the doubler, to which I very readily consented. I found 
the air in it agreeably warm, and full of moisture, which was 
condensed on the glass roof, and fell down in large drops. The 
doubler also, having been long expofed in frosty air, quickly 
attracted and condensed the humid particles upon itself, so as 
to form a coating on all its parts. I therefore hastened to make 
the experiment; yet under all these unfavourable circum- 
stances the doubler became electrified negatively after about 
MDCCXCI V, N n 
