54 Mr Rowell on the Phenomena of Evaporation. 
Vapour, when raised, if condensed near the earth, is then 
surcharged by the contraction of its surface, and, being at- 
tracted to the condensing substance, forms dew; or, if the 
surcharge escapes to the earth, the vapour is rendered scarcely 
buoyant, and causes fogs, &c. 
When vapour rises to a distance from the earth, and is 
then condensed, the surcharge of electricity still buoys it up, 
and, forming an electrical atmosphere round each particle, 
prevents the formation of clouds or rain until this surcharge 
escapes ; and the more the vapour is expanded on its first 
rising, the greater will be its charge of electricity, and it 
will rise to a corresponding height. 
The vapour in the region of the clouds is generally, or at 
all times, condensed, but invisible, from its being so dif- 
fused: the breath of animals is condensed and visible, in 
cold weather, close to the mouth, but invisible at a short 
distance off, where it is more condensed, but more diffused ; 
and the deep blue of the sky at great elevations, as described 
by Saussure, Humboldt, and others, makes it probable that 
the light colour of the sky at lower latitudes is owing to the 
condensed vapour floating in the air. 
The formation of clouds is, in general, not owing to the 
sudden condensation of the vapour, but from the escape of 
its electricity, thus allowing the particles to be brought 
nearer by the attraction of aggregation ; and a still further 
escape of the electricity enables such attraction to overcome 
the electrical repulsion of the particles, and form rain. 
Mountains and high hills cause rain, by conducting the 
electricity from the clouds and vapour, and not as condensers 
of vapour. 
Rain is also caused by the air between the earth and 
clouds becoming charged with vapour, and thus conducting 
the electricity from the vapour above. 
from a charged conductor ; but the fact that insulation retards evapora- 
tion, shews that electricity is a necessary agent. 
The electricity of steam also supports this theory. See Article on the 
subject in last vol., p. 347. 
