ISL. | 
and in every other circumstance differ- 
ent from that of combustion. This phi- 
losopher obtained the prize on the same 
subject the last year; his present re- 
searches have considerably enlarged the 
results of his former experiments. He 
defines phosphorescence to be the ‘ap- 
pearance of a durable or transient light, 
unattended with sensible heat, ‘and not 
followed by any alteration in inorganic 
‘bodies. This phosphorescence presents 
itself under different forms, and like so- 
lar light is decomposed by the prism. 
From some bodies it seems to emanate 
slowly and regularly, in others by scin- 
tillation. - Its colouris blue, but appears 
tarnished in those bodies which contain 
iron; it may, however, be rendered 
clear, by separating the metal from the 
bodies which contain it. In general, it 
has appeared to M. Dessaignes, that 
those bodies are the most phosphores- 
cent, that contain in their composition 
principles which can ‘pass from a state 
of gas, or liquid, to a solid form.’ All 
bodies give out light by compression, 
whether they are fluid, solid, or gaseous. 
He lias also discovered that points have 
the saiwne effect on phosphorescence as 
vpon the electric fluid. M- Dessaignes 
distinguisties two ‘kinds of phosphores- 
cence ; the one transient, the other per- 
manent. Amongst the first we may state, 
that which takes place when a certain 
‘quantity of water combines with quick 
lime ;, amongst the latter, that of rotten 
wood, and other organised ‘substances 
in a state of putrefaction, It appeared 
‘important to determine whether the 
phosphorescence that takes place ih 
those bodies, which become luminous 
when their temperature is somewhat 
increased, is owing to combustion, 
‘M. Dessaignes made experiments in at- 
mosplieric air, in oxygen gas, and in the 
torricellian’ vacuum, to ascertain this 
point; but he could perceive no. differ- 
ence in the intensity of the light under 
the different circumstances, when the 
experiments were made on inorganic 
bodies ; but the light of organic bodies 
was encreased in oxygen, from which 
the author concludes that some part of 
this light in the latter is owing to com- 
bastion. 
These Juminous organic bodies more 
particularly occupied his attention; he 
made ‘expesiments on fresh water fish, 
sea fish, and various kinds of wood, 
The results have proved, that the phos. 
horescence of cach is a species of com- 
ustion, in which water and carbonic 
Proceedings of Learned Societies. 
355 
acid are produced, Thé woody parr, 
and muscular fibre, do not undergo iu 
these changes any essential alterations, 
The phosphorescence of the wood is 
chiefly owing to a glutinous principle, 
that serves to unite the woody fibres 
and that of the fish, to a gelatinous prins 
ciple, which anites the muscular fibres: 
M. Dessaignes has endeavoured to exs 
plain the luminous appearance of the 
sea, apd to support his reasoning by a 
numerous collection of facts relating to 
spontaneous phosphorescence. He at* 
tributes thelight of the sea to two causes; 
first, to the presence of phosphoric ani+ 
malcule, and the enianation of laminous 
matter produced by them; and,secondly, 
to the simple presence of this niatter 
dissolved and mixed in the water, pros 
ceeding not only from these animalcula, 
but from molusci, fish, &e. 
Mathemutics—The subject of the 
double prize of 5000 francs to be distri 
buted by this class, in its sitting, January 
7th, 1811, was the following: 
“ The theory of those planets which 
have an inclination and eccentricity too 
great to admit the calculation of their 
irregularities with sufficient exactness by 
known methods.” ’ 
The class did not require a numerical 
application, but only analytical formu- 
laries, disposed im such a manner that‘at 
intelligent calculator could apply them 
with certainty to the planet Pallas, and 
to every other which are er may be dis- 
covered. Two wemoirs were presented 
which were not satisfactory; the class 
therefore proposed to’ reserve the deter= 
mination of the prize to the tst of Ja- 
nuary, 1816, that geometricians may have 
sufficient time to resolve this important 
question. 
The medal of M.de Lelande for the 
Most interesting observation, or the most 
useful memoir, on astronomy, for the 
last year, has been given to M. Poisson, 
for his works relating to’the secular ine- 
qualities of the mean motions of the 
planets, the stability of the planetary 
system, the rotation of the earth, the 
change of place of the poles atthe surface, 
and the equations on which the move. 
ments of its axis depend. These works 
have merited the gratitude of astrana. 
mers, to whom he ‘has demonstrated in 
the most complete manner hitherta 
done, ‘the fundamental , points of the 
system of the world, which ave the base 
of all astronomical calculations, 
Geology.— Messrs. Cuvier and Bronre 
niart, ave discurered, in the environs uf 
Yuls, 
