CHEMISTRY. 
rapidity, if their temperature be raifed : the decompofi- 
tion takes place with fo much velocity as to occafion a 
confiderable and almoft inffantaneous decrepitation or 
detonation. The operation in open veifels is as follows : 
Put a certain quantity of nitre into a crucible, which 
place in a furnace among burning coals; when the nitre 
is melted, and the veflel begins to be red, put in a fpoon- 
ful of charcoal in powder, which will be followed by a 
loud detonation ; then put in another fpoonful, and lo 
proceed till the charcoal produces no detonation. A la- 
line, matter remains in the crucible; this is to be cal¬ 
cined, and afterwards diffolve the fait in the water; drain, 
and evaporate to drynefs: this was formerly called nitre 
fixed by charcoal : if the liquor, fomewhat concentrated, 
was preferved, it was then called fixed liquor of nitre, and 
alkahefi of Van Helmont. Modern chemilts difcern in this 
operation, only a little potalh, more carbonic acid formed 
by the decompofition of the nitric acid, whole oxygen 
is driven upon the charcoal. 
The following is the mode of decompofing nitrat of 
potalh with charcoal, in clofe veflels: Two or three large 
receivers, adapted together, are applied to a retort of 
earth or iron, in the upper part of which lafi is an aper¬ 
ture, which may be doled with a cover or Hopper. The 
velfel is heated, and, when its bottom is red, the equal 
mixture of nitrat of potalh and charcoal is thrown in by 
fmall quantities at a time, through the aperture, which is 
immediately clofed. During the detonation, the receivers 
are filled with vapours, part of which condenles into an 
infipid liquor, not at all acid, but frequently alkaline; 
the relidue confift of potalh charged with carbonic acid, 
and is called clyfius of nitre. If a mixture of nitre and 
lighted charcoal be put in a tube, and plunged into wa¬ 
ter, the combultion continues ; and thus the gafes refult- 
ing from this combultion may be gathered with the pneu¬ 
matic apparatus. 
To make what is called fulminating powder, put into 
a marble mortar, which has been heated with boiling 
water, and well dried, three parts of very dry nitrat of 
potalh, two parts of very dry potalh, and one of fulphur, 
in .fine powder: mix thele materials well together by 
pounding with a glafs peltle heated and dried in the fame 
manner: put this mixture in a bottle very dole Hopped. 
The property of this powder is to produce, on being ex¬ 
pofed to the fire, a very Hrong and loud explofion. Put a 
little of the powder in an iron-ladle over a very gentle fire; 
the powder melts; when it has attained a certain degree 
of heat, it flies off in vapours fuddenly, and an explofion 
is prodpced as loud as the report of a cannon. This 
feems to adt by double affinity. This phenomenon, which 
is fo much the more affonilhing, becaufe its effedt is pro¬ 
duced without enclofing the powder in any inffrument, 
as is done with gun-powder, may be explained, by ob- 
ferving, i. That it does not fucceed but by gradually 
heating the mixture, fo ps to melt it. 2. That, if fulmi¬ 
nating powder be thrown on ignited charcoal, it only 
fufes, like nitre, but with very little noife. 3. That a 
mixture of fulphure of potalh with nitre, in the propor¬ 
tion of one part of the former and two of the latter, 
fulminates with more rapidity, and produces as loud a 
report as the compofition of fulphur, nitre, and alkali: 
hence it appears, that, when fulminating pow r der is heat¬ 
ed, fulphure of potalh is formed before the detonation 
takes place ; and this fadt is lufiicient to explain the whole 
appearance. When cryffallized nitre, and fulphure of 
potalh are expofed to the action of heat, fulphurated hy¬ 
drogen gas is difengaged from the latter, while the lalt 
gives out vital air. Now thefe two, which together are 
capable of producing, a Hrong detonation, as we have ob- 
ferved in fpeaking of hydrogen gas, are let on fire by a 
portion of the fulphur. But as the thick fluid they are 
obliged to pafs through prefents a confiderabie obltacle, 
and as the whole takes fire at the fame inffant,. they ffrike 
the air with fuch rapidity that it refiffs in the fame man¬ 
ner as the chamber of a mulket refiffs the expapfion of 
Vol. IV. No. 19a. 
23 7 
gun-powder. A proof of this is obfervable in the effedt 
the fulminating powder has on the ladle in wdiich it ex¬ 
plodes. The bottom of this velfel is bulged outwards, 
and the fides bent inwards, in the fame manner as if it 
had been adted on by a force diredted perpendicularly 
downwards, and laterally inwards, though it may be 
eafily conceived that the effedt of the expldfion fliould be 
diredted equally on all tides, or circularly. 
If iron, copper, or zink, be heated with nitrat of pot¬ 
alh, thefe metals are oxyded, "and the potalh remains 
pure. This fait is very foluble, three or four parts of 
cold water diffolving one part of nitre, and boiling water 
diffolving twice its weight. It therefore cryffallizes by 
cooling; and on this property is founded the art of ex¬ 
tracting nitrat of potalh from old plalter or rubbilh. In 
palling from the folid to the liquid Hate it lowers the 
thermometer. 
A mixture of nitrat of potalh with o-i 5 of charcoal 
and o' 1 o of fulphur, compofes gun-powder, whofe ter¬ 
rible effedts arife from its great combuftibility. This 
mixture is triturated for ten or twelve hours, in wooden 
mortars, with peffles of the fame fubltance, a very fmall 
quantity of water being added from time to time. When 
almoff the whole of the fluid is evaporated, fo that the 
powder will not foil an earthen plate, it is carried to be 
granulated. This is effe'dted, by caufing it to pafs through 
a number of fieves of Ikin, which are moved backwards 
and forwards in a right line. The holes in thefe fieves 
are of various fizes, down to that of cannon powder. 
The duH, or meal powder, is feparated from the grains 
by lifting. The grains are then carried to the drying- 
houfe, which is a Hied expofed to the fouth, with glafs 
windows, fo as to receive the rays of the fun. Cannon 
powder receives no other preparation than we have here 
mentioned. Muflcet powder is glazed, that it may not 
foil the hands. To perform this operation, a calk, 
mounted on an axis, and turned by a water wheel, is 
half filled with powder. The motion of the calk excites 
continual fridtion, by which the grains of the powder 
are worn fmooth. 
Baume has made a very numerous fet of experiments 
on the method of preparing gun-powder, on the refpec- 
tive forces of this compound made with different propor¬ 
tions of the ingredients, and on the analyfis of this fub- 
Hance. Out of the many valuable circumffances of in¬ 
formation derived from thefe experiments, we fhall only 
fcledt fuch as have an immediate reference to chemical 
theory. 1. Good powder cannot be made without ful¬ 
phur, as has been propofed by feveral perfons; this fub- 
ffance being found greatly to increafe its force. 2. Eve¬ 
ry kind of charcoal, whetherlight or heavy, except ani¬ 
mal coal, is equally fit for making gun-powder. 3. 
Charcoal.is one of the moffufeful ingredients, a mixture 
of fulphur and nitre not producing an effedt to be com¬ 
pared with that of gun-powder. 4. The goodnels of 
gun-powder depends entirely on the accurate mixture 
and trituration, continued till the powder riles in the 
form of duff about the mortar. 5. Powder has a much 
greater effedt when Amply dried, than when grained. 
The moiffure neceffary to grain the pow'der, caufes the 
nitre to feparate, by cryffallization from the other fub- 
ltances; fo that it may be obferved, by a magnifier, in 
the internal part of grains of powder, cut in two. 6 . 
Glazed, or mulket powder, is lets Hrong than unglazed' 
powder, becaufe the particles of the former are cloler to¬ 
gether, and conlequently lefs inflammable. As to the 
analyfis of gun-powder, Baume performs it in a veiy 
fimple manner: his procefs confiffs in waffling the gun¬ 
powder, well pulverized, with aiitilled water, and eva¬ 
porating the water, which of courfe affords the nitre in 
cryffals; the refidue contains the fulphur and charcoal. 
Sublimation does not completely leparate the former, 
becaufe it appears to be partly more fixed by the char¬ 
coal. Baume, to feparate them, burned the fulphur by 
a heat not fuflicient to burn the charcoal. The latter, 
3 P however. 
