1925.] 
‘moir on the causes of electricity in the 
atmosphere, has attempted to prove that all 
chemical combinations disengage electric 
matter, from whence he concluded that 
vegetation necessarily becomes a_ constant 
source of the electricity furnished to the 
atmosphere. In the second part he exa- 
mines whether chemical decompositions 
do not also disengage the electric fluid; 
which is not a necessary consequence of 
the preceding, fer the contact of two 
metals disengages electricity, while nothing 
of the kind is observable on their separa- 
tion. M. Pouillet has particularly attended 
to the decompositions which are constantly 
taking place on the surface of the, globe, 
frem evaporation. He first examines the 
effect of simple evaporation. He employed 
an apparatus, in which the fiuid to be eva- 
porated is placed in a vessel of platina, and 
heated by a machine invented by M. Fres- 
nel;.and found, that perfectly pure water 
never disengages the least portion of electri- 
city, whether it be evaporated slowly or 
quickly ; but when the water is charged 
with particles of matter foreign to it, holding 
in solution strontian, chalk, and other solid 
alkalis, anda liquid alkali (ammonia), in 
whatever proportion, electricity was always 
disengaged during evaporation, with this 
difference, that the solid alkalis communi- 
eated to the apparatus vitreous electricity, 
and ammonia resinous electricity. Acetie 
acid, as well as all other acids, in a state of 
purity, do not disengage the slightest degree 
of electricity in evaporation; while a solution 
of these same acids always disengages elec- 
tricity; a solution of sulphuric acid [one 
part, and water 99 parts] proves the fact 
yery distinctly. 
. D. Costa read a memoir on the plague at 
Barcelona; he is an anti-contagionist, and 
he offers to have the clothes of a person 
who died of the yellow fever in the Havan- 
nah, or elsewhere, hermetically sealed up 
and sent to France ; that he will put them 
on and wear them at a sitting of the Insti- 
tute :—that learned body smiled, and po- 
litely declined such a proof of the non-con- 
tagion of the yellow fever. - 
Dr. Montegre, it is said, had a similar idea 
relative to contagion: he went to St. Domin- 
go to prove it,—the same packet brought the 
news of his arrival and death.—[But this 
proves nothing—except the illogical incon- 
siderateness of Dr. M.—The result was 
equally probable, whether the infection 
were contagious or atmospheric. If the 
pestilence was spread by the impure im- 
pregnation of the atmosphere, the Dr. put 
himself in the way,.of breathing no other 
» than the infected air; and, if the slightest 
predisposition existed in his constitution or 
state of health, the result was to be expected 
in one case as well as the other. This 
question is exceedingly embarrassed from 
Proceedings of Learned Societies. 
51 
the want of attention to accurate definition. 
Eprr. ] 
Geographical Society of Paris, Decem- 
ber 3, 1824.—A thousand franes (about 
£40. sterling) was offered to the first 
traveller who should penetrate to Tombuc- 
tou, by way of Senegal, and thereby produce 
positive and exact observations as to the 
position ef that town, the course of the 
neighbouring rivers, and the commerce of 
which it is the centre; secondly, the most 
satisfactory and precise information with 
respect to the country comprehended be- 
tween TFombuctou and Lake Tsaad, the 
direction and height of the mountains 
which form the basin of Soudan. Count 
Orloff consented that the gift of a thou- 
sand francs, which he had made to the 
society on the 26th of November 1824, 
‘for the encouragement of geographical dis- 
coveries, should be devoted to the same 
purpose. Count Chabrol de Crousoul, on 
the 15th of December following, subscribed 
a thousand francs for the same. purpose, in 
the name of the administration of the 
marine; and in January last, the Baron de 
Damas subscribed two thousand frances in 
the name of the administration for foreign 
affairs; and on the: 19th of Mareh, the 
Count de Corbiére a thousand francs in the 
name of the administration of the interior. 
Several other subscriptions have since been 
added. The Geographical Society has be- 
sides resolved to offer a gold medal of the 
value of two thousand frances, to the traveller 
who, independently of the conditions already 
mentioned, shall produce a manuscript 
narrative, with a geographical map, founded 
on celestial observations ; study the country 
with a view to the various objects of physical 
geography ; observe the nature of the soil, 
the depth of the wells, their temperature, 
and that of the springs; the size and 
rapidity of the rivers, the colour and clear- 
ness of their waters, and the productions of 
the countries which they irrigate ; make his 
remarks on the climate, and, if possible, de- 
termine in different places the inclination of 
the compass ; notice the breeds of animals, 
and make collections in natural history, 
. especially of fossils, shells and plants; and, 
when he has arrived at Tombuctou, if he 
can advance no farther, obtain information 
as to the roads which lead to Kachnah, 
to Kaoussa, to Bournou and Lake Tsaad, 
to Walet, to Tischit, and to the coast of 
Guinea; collect the most exact itineraries 
he can procure, and consult the best in- 
formed inhabitants, with regard to that part 
of the Dialliba, which he may be unable 
to see himself ; carefully examine the man- 
ners, ceremonies, costumes, arms, laws, 
religion, food, colour, shape, trades, &ce. of 
the people; form vocabularies of their 
idioms, and, finally, sketch details of their 
dwellings, and plans of their towns, &c. 
H 2 PATENTS 
