1809.] 
contested experiments of Dr. Iferschel, 
on the mode of its union with heat in the 
solar rays. 4 
We then come to the history of the 
discoveries relative to heat itself; which 
constitute a system so new, that the phi- 
losophers ef the first half of the eigh- 
teenth century had no ideas whatever 
of it. 
The first germs of it are to be traced 
back to upwards of forty years, and we 
are indebted for them to the Scotch 
chemist, Black; and to the Swede, 
Wilke. They first observed, that not 
only a body absorbed a great quantity of 
heat, in melting, and in evaporating, and 
restored it in returning to its primitive 
State; but also, that different quantities 
of heat are necessary, to bring different 
bodies to the same degree of tempera- 
ture ; these primary truths have produced 
a number of others, the influence of ° 
which,on the whole system of the sciences, 
as well as on domestic economy, and 
particularly on the arts, is incalculable. 
We give a rapid enumeration of those 
particular discoveries of the different 
capacities of bodies, for becoming con- 
ductors df heat, measured by Franklin 
and Ingenhouoz, of the particular man- 
ner in which liquids conduct it, as dis- 
covered by Count Rumford, in whose 
hands it became the source of so many 
useful processes; of. the calorimeter in- 
vented by M, Dela Place, to measare the 
heat produced, or which disappears, in 
each circumstance ; an instrument which 
has supported the theory of chemistry, 
by such beautiful demonstrations; of the 
various dilatabilities of the bodies, mea- 
sured by M.M. Dalton, and Gay Lussac, 
and so necessary to be known, in order 
to judge of thermometers; in short, 
of the theory. of vapours recently finish- 
‘ed by the same philosophers; the im- 
portance of which is su great, for the 
construction of stenm-engines, machines 
the most marvedous perhaps of ail those, 
with which the genius of science has 
enriched society. 
Galvanic electricity presents itself 
next, and offers to us a new scene, and 
regions of which no man yet dares to 
calculate the extent. The most power- 
ful perhaps of the agents, which nature 
employs in its operations, on the surface 
of our plobe, therefore remained hiddea 
until the present time. 
even ‘of any two different bodies what- 
ever, alters the equilibrium of electricity ; 
and wuhisalteration may produce the must 
Progress of the Sciences stnce 1789. 
The simple jux- - 
taposition, not only of two metals, but: 
403, 
violent commotions in the animal eco- 
nomy; it separates substances the most 
intimately united; at thi momentit ap- 
pears disposed to reveal the composition 
of the alkalies, which the mest profound 
chemistry had hitherto always presented 
to us, as simple bodies; in short, when in 
its full force, it is thunder itself; and in 
ws various degrees, it is perhaps the ses 
cret spring of a great number of pheno- 
mena, yet involved in mystery. The 
name of Galvani, who discovered the 
acuion of this electricity on animal eco~ 
nomy, that of Volta, who has demon- 
strated its origin and its nature, and who 
has taught how to encrease its force in- 
definitely ; those of Ritter, Nicholson, 
and principally that of Davy, who has 
discovered and established its chemical 
power ; are honourably recorded in this 
part of our report; amongst those of 
many other estimable natural philoso~ 
phers, who have enriched the theory of 
Gaivanism, by more particular experi- 
ments aud discoveries. 
After this theory of the imponderable 
chemical agents, so new in the history of 
the sciences, we proceed to chemistry, 
properly so called, and particularly to its. 
fundamental doctrine, the explanation of 
what takes place in combustion. - 
Here, undoubtedly, was effected the 
most important revolution that the 
sciences ever experienced ; a revolution 
at once so honourable for our times, and 
for our country; and which was not com- 
pleted before the commencement of the 
period, of which we give an account. 
Indubitably, during several years, facts 
had been accumulating, capable of over- 
setting the doctrine of phlogiston, and all 
the brilliant system of Stahl, notwithstand. 
ing the efforts made by Senac, Macquer, 
Rouelle, and Bergman, to support and 
illustrate it. The new theory, ‘is doubt. 
less only a link, which happily connects 
particular facts, discovered by different 
inep, and at very different times, The 
discovery of latent heat, by Black; that 
of the disengagement of air from the 
calees of mercuty, by Bayen ; that’of the 
production of fixed air, in the combus." 
tron of charcoal, by Cavendish; and of 
water in that of inflammable air, by the 
saire plnlosopher, and by M. Monge; 
are “ntegrant portions of the new che- 
mistry; as well as the increase of the 
weight of calcined metals, previously an- 
nounced by Libavius; and the absorption 
of air in calcinations, discovered as early 
as the time of Boyle. SHO 
- Gut it is precisely the good fortune of 
having. 
