62 
eoating of a greyish-white, covers that 
part of it which the Composition touched. 
M. Descostils having been led by curio- 
sity, to examme ee substance, found 
from various experiments that itis a com- 
-bination of oxide of silver, ammonia, 
and a vegetable substance, nearly similar 
to the fulminating mercury of Mr. How- 
ard. This substance termed by M. Des- 
costils detonating silver, in order to dis- 
tinguish it from the fulminating silver of 
M. Berthollet, is obtained by dissolving 
silver in pure nitric acid, and pouring in 
while the solution is going on, a sufficient 
quantity of rectified alcohol, or by adding 
the alcohol to a nitric solution of silver 
with a considerable excess of acid. In 
. the first.case, the nitric acid into which 
the silver has been put, must be slightly 
heated till the solution begins to take 
place, when it must be removed from the 
fire, and a sufficient quantity of alcohol 
added to prevent the liberation of any 
nitrous vapours. ‘There occurs a consi- 
derable disengagement of heat during the 
mixture of the two liguors; the efferves- 
cence immediately re-commences, but 
without any nitrous gas being disengaged, 
and gradually continues to increase, while 
at the same time there is emitted a strong 
smell of nitrous ether. The liquor soon 
becomes turbid, and deposites a white 
crystalline and very «ull powder, which 
must be separated and several times 
washed with small quantities of water. 
Ifa ready made and strongly acid solu- 
tion of silver be employed, it must be 
shghtly heated before pouring into it the 
alcohol; the heat produced by the mix- 
ture, which takes place very gradually, 
soon occasions a considerable ebullition, 
-and the powder is suddenly deposited. 
It may be perhaps proper to hint to those 
who may wish to amuse themselves with 
preparing this substance; that the mix- 
ture of aleohol and warm nitric acid is 
liable to many accidents, consequently 
they ought to operate in very smali quan- 
tities. From a great number of experi- 
ments it appears “that a very minute por- 
tion of this powder is sufficient to kiil the 
strongest animal; when pee to some 
cats, ‘all of them expired in the strongest 
convuleions. It is, we are informed, 
without exception one of the most vio- 
lent poisons which the metallic combina- 
tions furnish. 
In order to ascertain what relation ex- 
isted between manna and sugar, Messrs. 
Tnenarpand Dupuyrren have heenin- 
duced to enter into an examination of 
Literary and Philosophical Intelligence. 
‘tinue their investigation with this view a 
[Feb. 1, 
the former of these substances. With 
this view they took some manna, and after 
adding a portion of ferment to it, kept it 
ata temperature of 18°. The fermenta- 
tion was prompt and brisk; butit ceased 
at the end of two days. A vinous odour 
was emitted by the liquor, which far frona 
bemg alcoholic was saccharine, and on 
being subjected to evaporation, it depo- 
sited. under the form of crystals, nearly 
all the matter which had been employed, 
a wholly incapable of fermentation. 
Alcohol at the temperature of 609, pour- 
ed on the manna, dissolved such a great 
quantity of it, that the liquor, whencold, 
appeared as one mass coinposed ofa vast 
number of crystals. The nitric acid 
boiled with the manna produced such a 
great, deposition of mucous acid, that its 
weight ‘was almost equal to the half of 
that of the manna employed. ‘These 
different experiments evince that manna 
and sugar are materially differert from 
each other. 
M. Routeuvsgr has lately . discovered 
a new vegetable principle in asparagus; 
after a careful analysis of this vegetable, 
he found that it contained, 
ist, A green fecula puminenal of three ite. 
rent principles; the first of which is insoluble 
in alcohol, and very nearly approaches in its — 
nature to animal matter. ‘The second, terme 
ed vegetable wax, is soluble in alcohol at a 
certain temperature, but is again deposited 
on the solution becoming cool. "The third and 
last of these principles is likewise soluble in 
alcohol, is obtained by evaporation, and holcs 
a’middle place between volatile oils and re- 
sins. Q2dly, Albumen. 3dly, Phosphate of 
potash. 4thly, Phosphate of lime. held in. 
solution by a portion of free acetous acid, 
5thly, Terra foliata, or acetate of potash. 
and phosphate of potash. 6thly, A vege- 
to-animal substance. 7thly, An extractive 
matter. 8thly, A triple salt of lime ard 
ammonia, of which tee acid is unknown. 
9thly, A colouring principle, which becomes. 
of a rose colour, when treated with acids, and 
yellow byalkalies. This learned chemist, in 
conjunction with M. Vauquelin has since 
examined the triple salt, above mentioned. 
it is obtained in the form rhemboidal crys- 
tals, which nowever are not acid, since they 
do not redden turnsole; but neither was it 
found to contain any of the alkalies. These 
indefatigable chemists were nence led to cons 
clude that this substance is a principle peculicr 
to asparagus, the true nature of which remains 
yet to be discovered: and they propose 
as to discover, whether this singular matter 
exists in any other vegetable. The same 
chemists have also found in the juice of aspa- 
ragus a matter extremely analogous to manna. 
