242 Influence of atmospheric Moisture on 
their former extent, the middle of the glass tube was touched, 
and the leaves again closed. The leaves having regained their 
original divergence, the waxed extremities of the tube were 
touched in succession, the leaves experienced a diminution of 
their divergence each time, but did not quite close. 
Series 2. The wire of communication was removed from the 
negative end, by which the column became insulated: after 
waiting some time, the utmost divergence that the leaves attained 
was scarcely one-eighth of an inch; the tube was then touched 
as before, and the leaves instantly closed; this was repeated se- 
veral times with the same effect. 
Series 3. The column was now taken and held to the fire for 
about four or five seconds only, every part of it being exposed to 
its heat. It was then placed as described in Series 1, and the 
gold-leaves opened to the extent of three-fourths of an inch. The 
glass tube was then touched in various places, as well as its waxed 
extremities ; but no decrease in the divergence of the leaves en- 
sued; nor did any ensue when the contact was continued for se- 
veral seconds. ‘The communication with the ground was re- 
moved as in Series 2, and the touching repeated; but the leaves 
remained unaffected. 
The column was left thus insulated for about six minutes ; on 
returning to it at the end of that time, the leaves of the electro- 
mieter were seen diverging as in Series 2, about one-eighth of an 
inch; and on touching the glass tube they immediately closed, 
so quick had been the deposition of moisture on the glass. 
At the time the foregoing experiments were made, there ap- 
peared to be abundance of moisture in the air; the sky was 
covered with a continuous sheet of cloud, which was depositing 
moisture in drops so small as to be invisible ; and the streets and 
all objects out of doors were very wet. 
Series 4. Made on the 14th instant, when the atmosphere 
was in a drier state than in the former instance. ‘The column 
was in the position described in Series 2, and the gold-leaves di- 
verged three-eighths of aninch. The glass tube was touched, 
and the contact continued for a second or two, but the leaves 
experienced only a very slight diminution of their divergence. 
The negative end of the column was now made to communicate 
with the ground by putting a finger upon it; the gold-leaves 
doubled their divergence almost directly: the finger being re- 
moved, the glass tube was touched, and the leaves were imme- 
diately reduced to their original divergence of three-eighths of an 
inch. The same effect followed when the negative extremity of 
the column was kept in the hand while the tube was touched. 
The column was next presented to the fire for two or three 
seconds; and when its extremity was replaced upon the cap of 
“ 
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