586 
Gunpowder. plosive chemical compounds, such .as fulminating gold 
it pas silver, are fer Lac in their effects, because their 
formation is the result of chemical union. nt Neve 
The first business in preparing gunpowder, jis) to 
nd the materials, and pass them: through fine’ sieves. 
‘Then for 100 pounds of powder, weigh 75'4 nitre, 11.8 
sulphur, and 12.8 charcoal. These powders are, to be 
intimately mingled, till the mass. assumes a uniform 
colour ; that is, till no specks of yellow, white, or black 
appear ; for the nitre, after its crystals have been dried 
and powdered, becomes’ as white as flour, Water is 
now to be added, and the mass agitated till it assumes 
the form of a stiff but kneadable paste. In this state, 
it has been formerly kneaded or beaten: in mills, called 
turning mills. This apparatus consists of large mor- 
tars, with pistols or stampers of lignum vite. These 
are still worked in some manufactories, but in the works 
of government they are laid aside, on account of the 
danger arising from the heat of percussion. The ma- 
chine substituted for this seems much better. It con- 
sists of a large stone in the form: of a grindstone, which 
is made to roll upon its edge in the circumference of a 
circle. A vertical shaft turns in the centre of the cir- 
cle. A horizontal shaft works in the centre of the 
stone, the height of which is equal to the radius of the 
circle, in the periphery of which the stone is to roll, 
the éend-of this horizontal shaft being fastened into the 
vertical shaft. It will be evident that 'when the latter 
turns round, the rolling stone will go round just. as a 
cart wheel is. carried round by drawing the cart: for- 
ward, . The edge is a little rounded on‘the face, and 
works in a circular bed or trough, containing the paste 
to be worked or kneaded. The stone now goes round 
upon the paste, squeezing it flat. The point of con- 
tact is constantly preceded by a scraper, which goes 
round with the stone, and which constantly turns’ the 
paste, previously flattened, into the track of the stone, so 
Method of 
combining 
the mate- 
tials. 
Process of 
working the 
paste. 
that a new surface is always presented to its action. - 
The size of this apparatus is sufficient to work from: 50 
to 60 pounds at orice. It is driven by a steam engine, 
a water wheel, or by horses. 
The paste being sufficiently worked, which cannot be 
too much, is now sent to the corning house, where a se- 
parate mill is used for forming the paste into corns or 
grains. { 
Method of . J his process'is performed im sieves with parchment 
granulating bottoms, perforated with holes, These sieves are pla- 
the powder. ced upon a revolving horizontal plane. The paste, in 
a certain state of dryness, is put into the sieves, and a 
om of lignum vite in the shape of an oblate spheroid 
id upon it. A rotatory motion is given to the sphe- 
roid at the time the sieves are revolving. This forces 
the paste in small grains through the holes in the parch- 
ment, which is received below. 
The granulated matter consists of particles of very dif- 
ferent sizes, and some reduced to dust. These are pas- 
sed through wire sieves of different sizes} to give the 
different sized grains in which it is sold! Those which 
pass through the finest sieve, and which are called dust, 
are made up into paste, and worked over again. 
The proper grains are next to be glazed or polished. 
This is performed in a very expeditious manner, by put- 
ting the grains into a revolving cylinder, working like 
a barrel churn. This vessel should not be more than 
half full at once. The grains, by rubbing one against 
another, become smooth, and approach a spherical form. 
The next operation, which has been attended with the 
greatest danger, is the drying. This has generally been 
effected by placing the powder upon shelves on three 
Operation of 
polishing. 
Of drying. 
GUNPOWDER. 
‘preservin. gunpowder, using b:; of) 
rem ns w darn wre 
first who has examined ; ; 
-very properly conceived that its power consisted in the gunpow 
-evolution ‘of an abundance of some elastic fluid libera- 
the heat attendant on the explosion. Having convinced 
-himself that a permanently elastic fluid was generated 
-during the explosion of gunpowder, his next business g 
-weight of the powder. For this purpose, he exhausted Mr Rok 
-the receiver of an air-pump, the capacity. of which was 
sides of a small room; onthe other side of which is) an. 
iron stove; the fire being fed from the back of the wall. 
-When we;recollect that'the — itself is frequently hot 
enough: to explode gunpowder, it is’ surpri: ising that 
more aval ec rh ur bee adopted Steam ) 
pears:to be the:most proper agent to ; ; d 
only for the sakeof avoiding danger, but, it) 1s better 
calculated tovdry the powder a y without © © 
any fear of the powder being injured:in«its quality.) It - 
is eal hat pbs dosntie nba cdaiial too quick, or 
with too great a heat; for fear of volatilizing the sul- 
phur. Alithese precautions are -with steam, 
as sulphur only evap ‘at’ 220°! and: steam «would 
not raise it so. high as! 212° ‘without’ pressure. The 
shelves on whieh the powder is laid to dry might: be 
made of cast iron, and hollow. The:inner cavity might 
have a sloping bottom, so that when they steam: cante . 
into it from a boiler below, the water, after condensa- 
tion, might run back into'the:boilers There would, of 
course, be no waste of water, which should be rain. .wa< 
ter. The steam might be formed from afire at arsuffi- 
cient distance, to avoid the risk of any accidenti»'This 
method would. not beless desirable: in: an economical 
point of view... The powder ‘should: be kept on: the 
stove till the time of barrelling, for which the finest 
weather is always preferred. BEE 
A very great i has latel 
« 
i A Y, 
oy 
alcabes 
been made in 
Ins 
These barrels are first made water and 
air tight; and then the lid serews on so as to! exclude 
completely all) communication” with ‘the atmosphere. 
_ has been of the greatest importance, particularly in 
e navy. | j bt 
Having given the direct practical method of forming 
gunpowder, we shall now give some account of its che- 
mical properties, from which alone we can, get at any 
true theory of its effects. foqcammpyely ieee q 
The ingenious Mr Robins appears: to have been’ the chemice 
gunpowder scientifi “He prop 
ted in an instant, and strongly increased in its force by 
was to ascertain what proportion this bore'to-the whole ments 6 
equal to 520 cubic inches. In this he suspended a hot 
iron capable of firing gunpowder, and a mercurial gauge 
to ascertain the force of the air gen‘ On letting 
27 grains of powder fall on the iron, the mercury indi- 
cated an increase of elastic: fluid, which — yas 
inches; and upon repeatin the experiment, 
this result oda lecial The barometer at this time was 
30 inches, so that the quantity of elastic fluid 
was equal to #-th of an-atmosphere. He guesses the 
temperature of the receiver to be such’ as. to -increase 
the volume 3th of the whole. He then calculates: the 
weight of this volume of gas, allowing its specific gra~ 
vity to be the samme’ with common air, to weigh 131 
grains, for every ounce of 437.5 grains of gun) a 
which is 433, or nearly 3, of the whole. 
From determining the specific gravity of er, 
he found that the bulk of the powder tothe volume of 
gas generated, was as 1 to 244, ; 
e next supposes that the heat generated: by the ex- 
plosion of the powder, would have the same effect in 
expanding the generated elastic fluid which a red heat 
4 
