408 PELTIER ON THE CAUSES OF THE 
tricity have a leaden-blue colour, whilst those which are strongly 
vitreous are white, and adapted to reflect red. When we see a 
cloud with its head leaden-blue and its tail gray, we are certain’ 
of finding resinous signs before and vitreous behind, a distribu- 
tion which is imposed upon it by the induction of a heap of 
vitreous clouds which precede it. The flakes dispersed in the 
atmosphere which are coloured orange-red possess a great vitre- 
ous tension. If this state presents itself after rainy days, it is a 
sign of amelioration, it is an indication that the vapours are less | 
near the opacity which precedes their resolution into rain. The - 
contrary is the case after fine days, when this tint of the vapours 
is a sign of bad omen and a commencement of condensation. 
It is known that many physicians admit an intermediate state 
between pure elastic vapour and opake vapour. The Count de 
Maistre* and Professor Forbes of Edinburght+ are among those 
who maintain this opinion. 
56. When the series of vaporous transformations under the. 
influence of the temperature and the electricity of the globe 
shall be well understood ; when we shall have seen with what 
facility the opake clouds pass to the state of transparent clouds, 
and vice versa, always in presence of the earth powerfully charged 
with resinous electricity and of the celestial space not possessing 
the same resinous tension; when one single experiment shall have 
been made in order to be assured how quickly vapour is pro- 
duced under electric induction, then only will be understood the | 
different phenomena which may result from these masses of 
opake or transparent vapours, all charged with different degrees 
of resinous electricity, some possessing enormous tensions, others 
possessing less tensions, all tending to neutralize themselves, 
and only finding obstacles in the distances maintained by the 
difference of their gravity. We shall understand that when the 
superior transparent or opake clouds descend towards the earth 
with their powerful tension, they must produce great atmo- 
spheric perturbations, consequently energetic attractions and 
repulsions. When to these phenomena are added those of tem- 
perature, which condense or dilate these masses, which cause 
them to approach or recede according to their densities, we shall 
understand that electric phenomena may be produced at very 
different heights between these transparent or opake masses, 
* Bibl. Univ. Genéve, 1832, vol. li. 
+ Phil. Mag. 1839, vol. xiv. p. 419, and vol. xv. p. 25. , 
