29 FU™M 
gold. Its effects, however, are not so strongly marked 
as the two former, and it gradually loses its falminating 
property by keeping. Milbe ainiaciia is separated, leav- 
ing the red oxide unchanged. 
Another fulminating’ compound with mercury, was ——+— 
discovered by Mr Howard. ‘It is prepared, by dissol- Howard’s 
ving 100 grains of mercury in oné ounce and a half of flminating 
nitric acid of the common strength. When the solution ™"™: 
FUL 
lution with three times its volume of water ; and add 
pure aqua ammonia by a little at a time, so long as any 
precipitate is thrown down. Beyond this point, more 
ammonia would redissolve the precipitate, which is the 
substance to be obtained. 
In this process, the ammonia combines with the oxide 
of gold, forming an insoluble yellowish powder. This 
is to be: ted from the liquid, washed with pure 
water, and dried at a low heat upon filtering paper. 
When dry, it must be cautiously put into a clean bot- 
tle, the mouth of which must not be corked, but slight- 
ly covered with paper. Fulminating gold thus pre- 
pared has the following properties. It explodes by a 
smart blow from a hammer, or when sharply triturated 
ina mortar. It is also decomposed with sudden vio- 
lence when heated to about 250°. By all these means, 
the explosion is accompanied with a loud report, and 
the disengagement of elastic fluids, and is accompanied 
with light and heat. The hydrogen of the ammonia com- 
bines with the oxygen of the oxide of gold, forming 
water, which is dispersed in the form of highly elastie 
steam. The azote of the ammonia, at the same time, 
is evolved, acquiring great expansive force by the dis- 
engaged caloric. 
ulminating silver is prepared by first dissolving 
pure silver in nitric acid. By adding lime water to 
this solution, the oxide of silver is precipitated ; this 
oxide is now separated by filtering and washing. Pure 
ammonia is now to be poured upon the oxide, and al- 
lowed to remain upon it twelve hours. The liquid part 
is now to be carefully decanted off, and a black powder 
remains, which is the ammoniuret of silver, the sub- 
stance in question, It is now to be transferred with 
great caution, and by a little at a time, into as many 
portions of clean filtering paper. This powder is even 
capable of exploding, while moist, by a blow. When 
dry, it becomes so susceptible of decomposition: as to 
explode by the slightest touch. The liquid separated 
from the powder, on being heated in a glass retort, af- 
fords azotic gas and small opaque crystals soon begin 
to appear, of great brilliancy, having metallic lustre. 
These crystals are doubtless the true compound of am- 
monia with oxide of silver, owing their production in 
’ the crystalline form to their solubility in water. On 
ing touched, they detonate even when covered with 
the liquid in which they are formed. 
The same explanation which has been applied to the 
fulminating gold will apply to the substance in ques- 
tion, although the reason is not very obvious why the 
fulminating silver should be more easily decomposed. 
Perhaps it will be found, that the silver contains twice 
the quantity of oxygen with the gold, and. that the 
oxide of the former combines with twice the quantity of 
ammonia. 
’ Fulminating silver has been lately used in making 
what have been called fulminating balls. ‘These con 
sist of small bubbles of glass a little larger than a pea. 
A small portion of this compound is introduced at a 
little ing left for the purpose. The glass is then 
covered with paper. Any force capable of breaking the 
bubble produces the explosion. 
Mercury, from its weak affinity for oxygen, forms a 
detonating compound with ammonia, and other bodies 
containing much re The first of these com- 
pounds is formed, by digesting strong aqua ammonia 
upon the red oxide of mercury for ten or twelve days. 
At the end of this time, the oxide assumes a white co- 
Jour in crystals, having form of small scales. In 
this form, it fulminates by heat similar to fulminating 
3 
is cold, add to it two ounces of alcohol. Heat the mix- 
ture gradually till effervescence takes place. A greyish 
white precipitate will now be. formed, which must be 
separated by the filtre, washed with distilled water, and 
dried at a heat not exceeding’ 212°. 
This powder fulminates with great violence. A few 
grains laid upon an anvil, and struck with a hammer, 
gives a report as loud asa pistol. The same effect takes 
place, by triturating it in a mortar. 
It produces a much greater quantity of light than 
any other of the fulminating compounds, but very little 
heat. When it is,mixed with gunpowder, and a train 
of the fulminating mercury be Jaid into the mixture, 
and fired by the lighted paper, the whole of the fulmi- 
nating mercury will be consumed without firing the 
gunpowder. } 
hether fulminating mercury be exploded by heat 
or by percussion, the surface of the bodies near to it be- 
come covered with the vapour of mercury. 
This compound is said to consist of the oxide of mer- 
eury, combined with oxalic acids and a large quantity" 
of nitrous etherized gas. The explosive effect is to be 
attributed to the oxygen of the mercury combining with 
hydrogen in the etherized gas. 
The fulminating compound, eH $m of three’ parts. common 
sulphur, has been fulminating 
long known. When a little of this mixture is laid powder. 
nitre, two parts potash, and one o 
upon an iron shovel, and held over the fire, or placed 
upon burning ¢oals, or even held over the flame of a 
candle, it first melts, and then very suddenly explodes 
with a report equal to.that of -a musket. Equal parts 
of sulphuret of potash and nitre form the most perfect 
compound. Hence it is evident, that during the melt- 
ing of the first preparation, the sulphur unites with the 
potash, forming a sulphuret, which at the same mo- 
ment acts upon the nitre.. The explosive effects are 
to be attributed to the formation. and rapid evolution 
of sulphureted hydrogen and sulphurous acid gases, 
the disengagement of azotic gas, and the highly elastic 
steam from the water in the nitre and potash. (c. s.) 
FUMIGATION, in medicine, Satihen the mutation 
of different fumes, fur the relief of catarrhs, coughs, 
sore throats, &c. The term is also applied to the pro- 
cess of fumigating rooms during the prevalence of con- 
tagious disease. This has been long practised, but 
perhaps with little success, till the discovery of the me- 
thod proposed by Dr Carmichael Smith. We cannot ex~ 
pect much benefit to have been derived from the fumes 
of eg nor even from vinegar, which is more modern. 
f it be true that coptagio us diseases are derived 
from the presence of some elastic fluid existing in the 
atmosphere, which has been called miasma, and since 
these, of which there must be varieties, as well as the 
di eable odours resulting from putridity, in all pro- 
bability are inflammable matter, having hydrogen for 
their basis, it seems highly en ee ste ge “wd 
me result from fumigating the places where they pre- 
vail, with substances which easily combine with hydro- 
gen. Hence we are to attribute the good effects which 
were produced on board ships, and other places where 
contagious disease cervdligh by the use of the fumes 
