-1808.] 
through a series of flasks subjected to 
great cold. The ether is separated under 
the form of a yellow liquid, which must 
be freed, by means of lime, from the ni-' 
trous and acetous acids which it contains, 
even when it has been deprived of these, 
they are generated anew by the reaction 
of its principles; without requiring the 
contact of air. 
M. Thenard concludes from his expe- 
periments, that in these operations the 
oxygen of the acid combines with the hy- 
drogen of the alcohol, and with a small 
portion of its carbon; from whence re- 
suits much water, a considerable portion 
of gazeous oxide of azot, a small portion 
of acid, and of nitrous gaz, and a little 
free azot; that the ether is formed from - 
the union of the two principles of the ni- 
tric acid, with the dehydrogenized, and 
shehtly decarbonized alcohol, and that 
the residua of the carbon, the hydrogen, 
and the oxygen furnish the acetous acid 
and the carbonaceous matter. 
It may easily be conceived, how diffi- 
cult it must be thus to seize in their most 
minute details such evanescent actions, 
and to separate such various combinations 
which areso easily changed, and recipro- 
cally converted into each other. It is 
with the most lively regret, M. Cuvier 
adds, that the limits of his report does not 
permit him to exhibit a view of the inge- 
nious aid delicate processes employed by 
M. Thenard in these experiments. 
M. Cuvier next proceeds to notice the 
theory of Count Rumford respecting the 
cause of heat, which he attributes to cer- 
tain vibrations in the particles of bodies, 
and not to any particular matter, or to 
the caloric assumed by the greater part 
of chemists. ‘It has been objected to this 
theory that bodies acquire heat when 
condensed, or in other words as if con- 
densation expressed the caloric contained 
in them, and which no longer finding 
room, manifests its escape by its effects. 
Thus, water and alcohol mingled toge- 
ther lose a fortieth part of their bulk, and 
acquire several degrees of heat; thus pieces 
of money come out warm from the mint 
in which they have undergone compres- 
sion, &c, &ce. 
Count Rumford has endeavoured to 
invalidate these experiments by others 
which ate not less certain, and in which 
Condensation is accompanied, on the 
contrary, with a diminution of tempera- 
tare. Thus, solutions of different salts 
in pure water lose at once a portioa of 
‘their bulk and heat. It is well known, 
that salts frequently produce cold during 
their solution, a phenomenon, which is 
Proceedings of Learned Societies. 
573 
explained by the necessity of a solid body 
absorbing caloric, in order to become 
fluid. But this explanation does not ap- 
pear applicable, when a solution is sim- 
ply diluted with an additional portion of 
water. It is well known, that steam, 
when confined in a close veffel, acquires a 
heat superior to that of boiling water, and 
Count Rumford long ago discovered an 
expeditious and frugal method of-heating 
fluds, by the introduction of this vapour 
in a state of extreme heat. 
He has also successfully employed the 
same method in the manufacture of soap, 
and succeeded in boiling this substance 
to a suitable consistence in six hours, 
while not less than sixty were necessary 
according tothe usual method. The suc- 
cussions which the heated vapour gives 
to the mixture of oil and ley, on penetra- 
ting into and suddenly condensing it, 
contribute greatly according to. Count 
Rumford to accelerate the process of sa~ 
ponification. 
This intelligent naturalist has likewise 
succeeded in improving the vessels inten- 
ded to heat or evaporate liquids, by fix- 
ing in their bottoms various tubes whiclz 
descend into every part of the flame, by 
which means their surface is increased 
without any augmeniation of their dia- 
meter. In this way not only fuel is saved, 
but likewise the materials of which the 
vessel is formed, because, by opposing 
@ greater resistance to the action of 
the heated vapour, they do not require 
to be of such thickness. ey 
The science of meteorology depends 
almost wholly on the variable action of 
heat upon the atmosphere. It is the air 
differently heated which produces winds 
by the inequality of its dilatations; aud 
winds carrying vapours into warmer or 
colder places than those in which they are 
formed, occasion their more complete dis- 
solution, or their more or Jess sudden 
precipitation, or in other words, fine or 
rainy weather, 
'M. Dupont de Nemours, member of 
the histcrical class, has presented upon 
thissubject some reflections which clearly 
shew the inutility of all attempts to pres 
dict these phenomena from analogy and 
the experience of the past. 
Thus the zone of the most direct heat, 
namely that with the different points of 
which the sun corresponds vertically in 
the course of a year, is never precisely 
the same on the earth, not only two years 
successively, but during an infinity of ages, 
since the preceffion of the equinoxes, 
which only brings them back to the same 
points after more than twenty-six uae 
