How to refine nitre. Put into a copper, or any other vessel, 100 weight of rough nitre, with about 14 gallons of clean water, and let it boil gently for half an hour, and as it boils take off the scum; then stir it about in the copper, and before it settles put it into your filtering-bags, which must be hung on a rack, with glazed earthen pans under them, in which sticks must be laid across for the crystals to adhere to: it must stand in the pans for two or three days to shoot; then take out the crystals and let them dry. The water that remains in the pans boil again for an hour, and strain it into the pans as before, and the nitre will be quite clear and transparent; if not, it wants more refining; to effect which proceed as usual, till it is well cleansed of all its earthy parts.
How to pulverize nitre. Take a copper kettle, whose bottom must be spherical, and put into it 14lb, of refined nitre, with 2 quarts or 5 pints of clean water; then put the kettle on a slow fire; and when the nitre is dissolved, if any impurities arise, skim them off; and keep constantly stirring it with 2 large spattles till all the water exhales; and when done enough, it will appear like white sand, and as fine as flour; but if it should boil too fast, take the kettle off the fire, and set it on some wet sand, by which means the nitre will be prevented from sticking to the kettle. When you have pulverised a quantity of nitre, be careful to keep it in a dry place.
Different kinds of Gunpowder. It being proper that every one who makes use of gun-powder should know of what it is composed, we shall give a brief account of its origin and use. Gunpowder, for some time after the invention of artillery, was of a composition much weaker than what we now use, or than that ancient one mentioned by Marcus Græcus: but this, it is presumed, was owing to the weakness of their first pieces, rather than to their ignorance of a better mixture: for the first pieces of artillery were of a very clumsy, inconvenient make, being usually framed of several pieces of iron bars, fitted together lengthways, and then hooped together with iron rings; and as they were first employed in throwing stone shot of a prodigious weight, in imitation of the ancient machines, to which they succeeded, they were of an enormous bore. When Mahomed II. besieged Constantinople in the year 1453, he battered the walls with stone bullets, and his pieces were some of them of the calibre of 1200lb. but they never could be fired more than four times in the 24 hours, and sometimes they burst by the first discharge. Powder at first was not grained, but in the form of fine meal, such as it was reduced to by grinding the materials together; and it is doubtful, whether the first grain of it was intended to increase its strength, or only to render it more convenient for the filling it into small charges, and the loading of small arms, to which alone it was applied for many years, whilst meal-powder was still made use of in cannon. But at last the additional strength, which the grained powder was found to acquire from the free passage of the fire between the grains, occasioned the meal-powder to be entirely laid aside. The coal for making gunpowder is either that of willow or hazle; but the lightest kind of willow is found to be the best, well charred in the usual manner, and reduced to powder. Corned powder was in use in Germany as early as the year 1568; but it was first generally used in England in the reign of Charles I.
| Government powder, | - | |
| Ordnance-powder, |
such powder, as having undergone the customary proof, is so called, and received into the public magazines.
It has been recommended by a French writer to preserve gunpowder at sea by means of boxes, which should be lined with sheets of lead. M. de Gentien, a naval officer tried the experiment by lodging a quantity of gunpowder, and parchment cartridges, in a quarter of the ship which was sheathed in this manner. After they had been stowed for a considerable time, the gunpowder and cartridges were found to have suffered little from the moisture; whilst the same quantity, when lodged in wooden cases, became nearly half rotted.
Proof of Gunpowder, first take out of the several barrels of gunpowder a measure full, of about the size of a thimble, which spread upon a sheet of fine writing paper, and then fire it, if the inflammation be very rapid, the smoke rise perpendicular, and the paper be neither burnt nor spotted, it is then to be judged good powder.
Then 2 drams of the same powder are exactly weighed, and put into an eprouvette; which if it raises a weight of 24 pounds to the height of 3¹⁄₂ inches, it may be received into the public magazine as proof.
Gun-powder prover. See [Eprouvette].
GUNSHOT, the reach or range of a gun. The space through which a shot can be thrown.