ELECTRIC PHA NOMENA OF THE ATMOSPHERE, 405 
this electric production. It is evident, as M. Belli* has stated, 
that since the water falls vitreous, it is because the vapour which 
it has furnished was resinous. It is not the atmosphere which 
furnishes this electricity, for if the upper rod of an electrometer 
be made to pass through the same arc, the index will return to 
0 after having deviated during the elevation of the point. Ina 
very favourable day, the wet plate is sufficient for the phzeno- 
menon; the electroscope gives a slight vitreous indication. Se- 
eondary causes, such as oxidation, which makes the plate resin- 
ous, and the imperfection of the insulation during evaporation, 
do not allow of so great a manifestation as when the drops of 
water fall suddenly with their electric charges; but neither ex- 
periment leaves any doubt respecting the cause of the electricity 
of the vapours of the atmosphere. 
50. There is a notable difference between the results of Nature 
and those of our experiments, principally in the succession of 
the transformations which we have related. In Nature, the su- 
perior empty space is not a body; the electric vapours do not 
become neutralized by contact with it; they are diffused, preser- 
ving all their electricity until the superior attraction is counter- 
balanced by their gravity. Space then is not a receptacle of 
vitreous electricity, since it enables the vapour to preserve its 
high resinous tension ; it is only deprived of an action similar to 
that ofthe globe. It is otherwise with the last opake vapours 
which pass to the elastic state, and which are vitreous; if they 
do not come into contact with the earth to be there neutralized, 
it is because their specific lightness counteracts the terrestrial 
attraction ; but when they can approach the ground or trees, they 
discharge themselves and become neutral; they no longer pre- 
serve any of the vitreous tension which they possessed. We see 
that in these transformations, produced by the elevation and 
depression of temperature of each day, the vapours are divided 
more and more into masses electrified to different degrees ; that 
those most elevated in the atmosphere are the most resinous, and 
possess the greatest tension; that their elevation beyond the 
point assigned by their weight increases as the square of this 
tension, whether we consider the terrestrial repulsion alone, or 
combined with the superior attraction of space. 
51. Among the intermediate clouds, there will be some less 
resinous than the globe ; these will be attracted by the earth and 
* Bibl. Univ. 1835, t. vi. p. 148. 
