all the sulphur and charcoal remaining a fixed mass upon the filter. These respective quantities may be ascertained without much diffì. culty. The water containing the dissolved saltpetre, must be eva. porated by a gentle heat; the saltpetre cannot be evaporated by the same degree of heat which evaporates the water; all the saltpetre then contained in the gunpowder, will remain after the water is dispersed, and being carefully collected and weighed, it will shew the quantity of saline matter contained in the powder. Dry the mass of sulphur and charcoal, by laying the filtering paper containing it before the fire; it should be made as dry as the powder was before it was dissolved in the water in that state weigh the saltpetre and charcoal; and, when the experiment has been accurately made, the weight of the saltpetre, added to that of the mix. ture of sulphur and charcoal, will just amount to four ounces, the weight of the powder. The quantity of saline matter contained in any specimen of gunpowder, being thus ascertained, its quality may be known by dissolving it in water, and crystallizing it; if any part of it crystallizes in little cubes, it is a sign that it contains sea-salt; or if any part of it, after being duly evaporated, will not crystallize, it is a sign that it contains another sort of impurity, called by saltpetre makers, the mother of nitre, which powerfully attracts the humidity of the air.

The gunpowder marked FF, was analysed in the following man. ner. Twenty-four grains, by evaporating the sulphur, were re. duced to nineteen; these nineteen grains gave, by solution in water and subsequent filtration and crystallization, sixteen grains of saltpetre; the charcoal, when properly dried, weighed three grains. According to these proportions, 100 pounds of this kind of gunpowder consisted of

I tried this gunpowder in two or three

100 lbs.

other ways by taking

larger quantities of it, but the quantity of saltpetre was always 66 lb. together with some fractional part of a pound, from 100lb. of gunpowder. The powders marked with a single and a double

differ in the size of the grain, but they do not seem to differ, as

far as I have tried them, in the quantity of the saltpetre they contain. From some sorts of powder, I have got after the rate of 76lb. of saltpetre, from 100 lb. of the gunpowder.

The method of analysing gunpowder, by evaporating the sulphur, is not wholly to be relied upon; I have often observed, that when mixtures of sulphur and charcoal have been exposed to evapora. tion, on a plate of heated copper, the remainder has weighed less than the charcoal which entered the composition, part of it having been carried off by the violent evaporation of the sulphur: and hence the proportion of sulphur in the above analysis is probably too great. I am aware that this observation is wholly opposite to the conclusion of M. Beaumé, who contends, that one twenty-fourth part of the weight of the sulphur employed in any mixture of sulphur and charcoal, adheres so strongly to the charcoal, that it cannot be separated from it without burning the charcoal.-I can only say, that he separated the sulphur by burning it, and I separated mine by subliming it without suffering it to take fire, and this difference in the manner of making the experiment, may perhaps be sufficient to account for the different results.But it is unnecessary to pursue this subject further; there are several things to be attended to in forming a complete analysis of gunpowder, which any person tolerably well versed in chemistry, would certainly take notice of, if the analysis of any particular powder was required to be made, and which cannot, in this general view, be minutely described: and, indeed, it is the less necessary to enter into a detail on this subject, as the strength of the powder is not so much affected by small variations in the quantities of the sulphur and charcoal, which enter into its composition; and the method of ascertaining the quantity and quality of the saltpetre, in any particular gunpowder, has been sufficiently explained.

In order to judge with more certainty concerning the effect of sea salt, when mixed with saltpetre in attracting the humidity of the air, I made the following experiment. Five parts of pure saltpetre in powder, were exposed for a month to a moist atmosphere, but I did not observe that the saltpetre had gained the least increase of weight; for the same length of time, and in the same place, I exposed four parts of saltpetre mixed with one of common salt, and this mixture had attracted so much moisture, that it was in a state of fluidity.

[Bishop Watson.

Besides saltpetre or the nitric acid, which is the active ingredient in saltpetre, there are various other acids, as the oxymuriatic, (chlorine of Davy), the hyper oxymuriatic, the arsenic, tungstic, molybdic, and columbic, that are powerful supporters of combustion. Of these the most easy of access is the oxymuriatic; and this has in consequence been tried either instead of, or in conjunc tion with, the nitric acid, to ascertain whether it be possessed of more power. The best experiments upon the subject are those of Edward Howard, Esq. as communicated to the Royal Society. The effect, according to these, is very singular, in the employment of the oxymuriat of potash, the only form in which the oxymuriatic acid has hitherto been made use of. It acts with considerably more energy so far as its range extends; but this range is far short of that produced by saltpetre, or nitrat of potash. It produces also a much more violent explosion; and an explosion which, in one instance, burst the vessel, and nearly destroyed the eye-sight of the bold and ingenious experimenter. [Editor.

CHAP. XIV.

FULMINATING POWDERS.

THERE are various combinations under this name that possess a near resemblance to gunpowder in their constituent parts, easily inflame, and explode with great violence, but require a certain degree of heat to produce this effect. We shall notice the com. mon and the metallic fulminating powders.

SECTION I.

Common Fulminating Powder.

Tuis is prepared as follows: take three parts of nitre, two of purified pearl-ash, and one of flowers of sulphur, mix the whole very accurately in an earthen mortar, and place it on a tile or plate before the fire, till it is perfectly dry: then transfer it while hot into a ground stopper bottle, and it may be kept without injury for any length of time. In order to experience its effects, pour from ten to forty grains into an iron ladle, and place it over a slow fire:

in a short time the powder becomes brown and acquires a pasty consistence; a blue lambent flame then appears on the surface, and in an instant after the whole explodes with a stunning noise and a slight momentary flash. If the mass be removed from the fire as soon as it is fused, and kept in a dry well-closed vial, it may at any time be exploded by a spark, in which case it burns like gunpowder, but more rapidly and with greater detonation; but this effect cannot be produced on the unmelted powder, how accurately soever the ingredients of it are mixed together. When fulminating powder is in fusion, but not heated to the degree necessary to produce the blue flame. a particle of ignited charcoal thrown upon it will occasion immediately a remarkably loud explosion.

It appears that the ingredients of this powder do not acquire their fulminating property till combined by fusion; in other words, till the pot-ash of sulphur form sulphuret of pot-ash: whence fulminating powder may also be made by mixing sulphuret of potash with nitre, instead of by adding the sulphur and alkali sepa

rate.

In all these the cause of the detonation, or fulmination, is not accurately understood. In simple fulminating powder, there is a very large portion of elastic gass evolved; in fulminating gold or silver, a much smaller; yet the explosion in the latter case is infinitely greater than that in the former.

Fulminating Gold.

Dissolve pure gold in nitro-muriatic acid to saturation, and di. lute the solution with three times its bulk of distilled water, and add to it gradually some pure ammonia; a yellow precipitate will be obtained, which must be repeatedly washed with distilled water, and dried on a chalk stone, or in a filter. When perfectly dry, it is called fulminating gold, and detonates by heat, as may be shewn by heating a few grains of it on the point of a knife over the candle.

Fulminating Silver.

Dissolve fine silver in pale nitric acid, and precipitate the solu tion by lime-water; decant the fluid, mix the precipitate with liquid ammonia, and stir it till it assumes a black colour; then de cant the fluid, and leave it in the open air to dry. This product is fulminating silver, which when once obtained cannot be touched

without producing a violent explosion. It is the most dangerous preparation known, for the contact of fire is not necessary to cause it to detonate. It explodes by the mere touch. Its preparation is so hazardous, that it ought not to be attempted without a mask, with strong glass eyes, upon the face. No more than a single grain ought at any time to be tried as an experiment. This was invented by M. Berthollet.

M. Chenevix has invented a fulminating silver, not so dangerous as that just mentioned. It explodes only by a slight friction in contact with combustible bodies. It is thus prepared: diffuse a quantity of alumina through water, and let a current of oxygenated muriatic acid gass pass through it for some time. Then digest some phosphate of silver on the solution of the oxygenated muriate of alumina, and evaporate it slowly. The product obtained will be a hyper-oxygenated muriate of silver, a single grain of which, in contact with two or three of sulphur, will explode vio lently with the slightest friction.

Fulminating Mercury.

The mercurial preparations which fulminate, when mixed with sulphur, and gradually exposed to a gentle heat, are well known to chemists they were discovered, and have been fully described, by Mr. Bayen.

MM. Brugnatelli and Van Mons have likewise produced fulminations by concussion, as well by nitrat of mercury and phos. phorus, as with phosphorus and most other nitrats. Cinnabar also is amongst the substances which, according to MM. Fourcroy and Vauquelin, detonate by concussion with oxymuriat of potash.

M. Ameilon had, according to M. Berthollet, observed, that the precipitate obtained from nitrat of mercury, by oxalic acid, fuses with a hissing noise.

But mercury, and most, if not all its oxyds, may, by treatment with nitric acid and alcohol, be converted into a whitish crystallized powder, possessing all the inflammable properties of gunpowder, as well as many peculiar to itself.

"I was led to this discovery," says Mr. Howard, the inventor, "by a late assertion, that hydrogen is the basis of the muriatic acid : it induced me to attempt to combine different substances with hydrogen and oxygen. With this view I mixed such substances with