Therefore when any of the above mentioned accidents happen to your powder, you may recover it by applying to the directions here given; for example, if you imagine that the powder has not received much damage, proceed thus. Spread it on canvas, or dry boards, and expose it to the sun, then add to it an equal quantity of good powder, and mix them well together, and, when thoroughly dry, barrel it up, and put it in a dry and proper place. But if gun-powder be quite bad, the method to restore it is as follows; first, you must know what it weighed when good; then, by weighing it again, you will find how much it has lost by the separation and evaporation of the saltpetre; then add to it as much refined saltpetre, as it has lost in weight, but as a large quantity of this would be difficult to mix, it will be best to put a proportion of nitre, to every twenty pound of powder; when done, put one of these proportions into your mealing table, and grind it therein, till you have brought it to an impalpable powder, and then searce it with a fine sieve; but if any remain in the sieve that will not pass through, return it to the table, and grind it again, till you have made it all fine enough to go through the sieve; being thus well ground and sifted, it must be made into grains in the following manner, first you must have some (copper wire sieves) made according to what size you intend the grains should be; these are called corning sieves or grainers, which being provided, fill them with the powder composition, then shake them about, and the powder will pass through the sieve formed into grains. Having thus corned your powder, set it to dry in the sun; and when quite dry, searce it with a fine hair sieve in order to separate the dust from the grains. This dust may be worked up again with another mixture; so that none of the powder will be wasted: but sometimes it may so happen, that the weight of the powder when good cannot be known; in which case add to each pound an ounce or an ounce and a half of saltpetre, according as the powder is decayed, and then grind, sift, and granulate it as before directed.
N. B. If you have a large quantity of powder, that is very bad, and quite spoiled; the only way is to extract the saltpetre from it, according to the usual manner: for powder thus circumstanced, would be very difficult to recover.
Of Silent Powder, commonly called White Powder.
It would be rather absurd for any one to imagine, that it is possible for gunpowder to have any effect without some report, when it is plain and well known, that the sound does not proceed from the powder only, but from the air being rarified by the expansion of the powder.
From whence it is evident, that any composition acting with the same explosive force as gun-powder, would certainly produce the same effect, in every respect. However as for such sort of powder I never had any proof, nor ever knew any experiment made of it, but have so little opinion of it, that I should not have given it a place in this work, had it not been treated of by some authors of note; and at the same time giving every one, who is fond of this art, an opportunity of making experiments, and of knowing every thing belong thereto.
To make Silent Powder.
For the first sort, mix two pound of borax, with four pound of gun-powder.
2d. Add half a pound of lapis-calaminaris, and half a pound of borax, to two pound of powder.
3d. To six pound of gun-powder, half a pound of calcined moles, with as much borax of Venice.
4th. To six pound and a half of saltpetre, eight pound and a half of sulphur, and half a pound of the second bark of an elder tree, burnt and ground to a powder, with two pound of common salt.