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acted with the greatest energy, but only within certain limits.

"The effects of the mercurial powder, in the last experiments made me believe that it might be confined, during its explosion, in the centre of a bellow glass globe. Having therefore provided such a vessel, seven inches in diameter, and searly half an inch thick, mounted with brass raps and astop-cock, I placed ten grains of merenrial powder on thin paper, laid on iron wire, 249th of an inch thick, across the paper, through the midst of the powder, and, closing the paper, tied it fast at both extremities with silk to the wire. As the inciosed powder was now attached to the middle of the wire, each end of which was connected with the brass caps, the packet of powder became, by this disposition, fixed in the centre of the globe. Such a charge of an electrialbattery was then sent along the wire, as a preliminary experiment (with Mr. Cuthbertson's electrometer) had shewn me would, by making the wire red hot, inflame the powder. The glass globe withstood the explosion, and of course retained whatever gasses were generated; its interior was thinly coated with quicksilver, in a very dirided state. A bent glass tube was now screwed to the stop-cock of the brass cap, which being introduced under a glass jar standing in the mercu rial bath, the stop-cock was opened. Three cubial inches of air rushed out, and a fourth was set at liberty when the apparatus was removed to the water tub. The explosion being repeated, and the air all received over water, the quantity did not vary. To avoid an error from change of temperature, the glass globe was, both before and after the explosion, immersed in water of the same temperature. It appears, therefore, that the ten grains of powder produced four cubical jaches only of air.

"To continue the comparison between the mercurial powder and gunpowder, ten grains of the best Dartford gunpowder were in a similar manner set fire to in the glass globe: it remained estire. The whole of the powder did not expode, for some complete grains were to be observed adhering to the interior surface of the gas. Little need be said of the nature of the asses generated during the combustion of the unpowder: they must have been carbonic acid 10 phureous acid gass, nitrogen gass, and (according to Lavoisier) perhaps hydrogen gass. As to the quantity of these it is obvious that it could Bud be ascertained: because the two first were, at least in part, speedily absorbed by the alkali of the nitre, left pure atter the decomposition of its

nitric acid."

The following description will give the experirental philosopher a clear idea of the instrument used in this business.

The ball or globe of glass is nearly half an inch thick, and seven inches in diameter. It has two Becks, on which are cemented two brass caps, each being perforated with a female screw, to receive the male ones: through the former a small hole is drilled; the latter is furnished with a perforated stud or shank. By means of a leather elise the neck can be air-tightly closed. When a portion of the powder is to be exploded, it must be placed on a piece of paper, and a small wire aid across the paper, through the midst of the powder: the paper being then closed, is to be ed at each end to the wire with a silken thread. One end of this wire is to be fastened to the end of the shank, and the screw inserted to half its

length into the brass cap; the other end of the wire, by means of a needle, is to be drawn through the hole. The screw being now fixed in its place, and the wire drawn tight, is to be secured by pushing the irregular wooden plug into the aperture of the screw, taking care to leave a passage for the air. The stop-cock is now to be screwed on. The glass tube is bent, that it may more conveniently be introduced under the receiver of a pneumatic apparatus.

"From some of the experiments in which the gunpowder proof and the gun were burst, it might be inferred, that the astonishing force of the mercurial powder is to be attributed to the rapidity of its combustion; and a train of several inches in length being consumed in a single flash, it is evident that its combustion must be rapid. But from other experiments it is plain that this force is restrained to a narrow limit, both because the block of wood charged with the mercurial powder was more shattered than that charged with the gunpowder, whilst the sand surrounding it was least disturbed, and likewise because the glass globe withstood the explosion of ten grains of the powder fixed in its centre; a charge I have twice found sufficient to destroy old pistol barrels, which were not injured by being fired when full of the best gunpowder. It also appears from the last experiment, that 10 grains of the powder pro duced by ignition four cubical inches only of air; and it is not to be supposed that the generation, however rapid, of four cubical inches of air, will alone account for the described force; neither can it be accounted for by the formation of a little water, which, as will hereafter be shewn, happens at the same moment; the quantity formed from ten grains must be so trifling, that I cannot ascribe much force to the expansion of its vapour. The sudden vaporition of a part of the mercury seems to me a principal cause of this immense yet limited force; because its limitation may then be explained, as it is well known that mercury easily parts with caloric, and requires a temperature of 600 degrees of Fahrenheit, to be maintained in the vaporous state. That the mercury is really converted into vapour, by ignition of the powder, may be inferred from the thin coat of divided quicksilver, which, after the explosion in the glass globe, covered its interior surface; and likewise from the quicksilver with which a tallow candle, or a piece of gold, may be evenly coated, by being held at a small distance from the inflamed powder. These facts certainly render it more than probable, although they do not demonstrate that the mercury is volatilized; because it is not unlikely that many mercurial particles are mechanically impelled against the surface of the glass, the gold, and the tallow.

"As to the force of the dilated mercury, Mr. Baumé relates a remarkable instance of it, as follows:

Un alchymiste se présenta à Mr. Geoffroy, et l'assura qu'il avoit trouvé le moyen de fixer le mercure par une operation fort simple. Hat construire six boites rondes en fer fort épais, qui entroient les unes dans les autres: la dernière etoit assujettie par deux cercles de fer qui se croisoient en angles droits. On avoit mis quelques livres de mercure dans la capacité de la première: on mit eet appareil dans un fourneau assez rempli de charbon pour faire rougir à blanc les boites de fer: mais, lorsque la chaleur eut pénétré suffisamment le mercure, les boîtes crevèrent, avec une telle explosion qu'il se fit un bruit épouvan

table: des morceaux de boites furent lancés avec tant de rapidité qu'il y en eut qui passèrent au travers de deux planchers; d'autres firent sur la muraille des effets semblables a ceux des éclats de bombes.'-Chymie Expérimentale et Raisonnée, tom. ii. p. 393.

"Had the alchemist proposed to fix water by the same apparatus, the nest of boxes must, I suppose, have likewise been ruptured; yet it does not follow that the explosion would have been so tremendous: indeed, it is probable that it would not, for if (as Mr. Kirwan remarked to me) substances which have the greatest specific gravity have like wise the greatest attraction of cohesion, the supposition that the vapour of water would agree with a position of sir Isaac Newton, that those particles recede from one another with the greatest force, and are most difficultly brought together, which upon contact colere most strongly.

"Before I attempt to investigate the constituent principles of this powder, it will be proper to describe the process and manipulations which, from frequent trials, seem to be best calculated to produce it. 100 grains, or a greater proportional quantity of quicksilver, (not exceeding 500grains), are to be dissolved, with heat, in a measured ounce and a half of nitric acid. This solution being poured cold upon two measured ounces of alcohol, previously introduced into any convenient glass vessel, a moderate heat is to be applied until an effervescence is excited. A white fume then begins to undulate on the surface of the liquor; and the powder will be gradually precipitated, upon the cessation of action and re-action. The precipitate is to be immediately collected on a filter well-washed with distilled water, and carefully dried in a heat not much exceeding that of a water bath. The immediate edulcoration of the powder is material, because it is liable to the reaction of nitric acid; and whilst any of that acid adheres to it, it is very subject to the influence of light. Let it also be cautiously remembered, that the mercurial solution is to be poured upon the alcohol.

"I have recommended quicksilver to be used in preference to an oxyd, because it seems to answer equally, and is less expensive; otherwise, not only the pure red oxyd, but the red nitrous oxyd, and turpeth, may be substituted; neither does it seem essential to attend to the precise specific gravity of the acid, or the alcohol. The rectified spirit of wine, and the nitrous acid of commerce, never failed, with me, to produce a fulminating mercury. it is indeed true, that the powder prepared without attention is produced in different quantities, varieties in colour, and probably in strength. From analogy, I am disposed to think the whitest is the strongest ; for it is well known that the black precipitates of mercury approach the nearest to the metallic state. The variation in quantity is remarkable; the smallest quantity I ever obtained from 100 grains of quicksilver being 120 grains, and the largest 132 grains. Much depends on very minute circumstances. The greatest product seems to be obtained when a vessel is used which condenses and causes most ether to return into the mother liquor; besides which, care is to be had in applying the requisite heat, that a speedy and not a violent action be effected. 100 grains of an oxyd are not so productive as 102 grains of quicksilver.

As to the colour, it seems to incline to black when the action of the acid of the alcohol is most Vicient, and vice versa.

"I need not observe, that the gasses which were generated during the combustion of the powder in the glass globe were necessarily mixed with atmospheric air; the facility with which the electric fluid passes through a vacuum made such a mixture unavoidable.

"The cubical inch of gass received over water was not readily absorbed by it; and as it soon extinguished a taper without becoming red, or being itself inflamed, barytes water was let up to the three cubical inches received over mercury, when a carbonate of barytes was immediately precipitated.

"The residue of several explosions, after the carbonic acid had been separated, was found, by the test of nitrous gass, to contain nitrogen or azotic gass; which does not proceed from any decomposition of atmospheric air, because the powder may be made to explode under the exhausted receiver of an air-pump. It is therefore manifest that the gasses generated during the combustion of the fulminating mercury, consist of carbonic acid and nitrogen gasses.

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The principal re-agents which decompose the mercurial powder are the nitric, the sulphuric, and the muriatic acids. The nitric changes the whole into nitrous gass, carbonic acid gass, acetous acid, and nitrate of mercury. I resolved it into these different principles, by distilling it pneumatically with nitric acid: this acid upon the application of heat soon dissolved the powder, and extricated a quantity of gass, which was found, by well-known tests, to be nitrous gass mixed with carbonic acid gass. The distillation was carried on until gass no longer came over. The liquor of the retort was then mixed with the liquor collected in the receiver, and the whole saturated with potass; which precipitated the mercury in a yellowish brown powder, nearly as it would have done from a solution of nitrate of mercury. This precipitate was separated by a filter, and the filtrated liquor evaporated to a dry salt, which was washed with alcohol. A portion of the salt being refused by this menstruum, it was separated by filtration, and recognized, by all its properties, to be nitrate of potass. The alcoholic liquor was likewiseevaporated to a dry salt, which, upon the effusion of a little concentrate sulphuric acid, emitted acetous acid, contaminated with a feeble smell of nitrous acid, owing to the solubility of a small portion of the nitre in the alcohol.

"The sulphuric acid acts upon the powder in a remarkable manner, as has already been noticed. A very concentrate acid produced an explosion nearly at the instant of contact, on account, I presume, of the sudden and copious disengagement of caloric from a portion of powder which is decomposed by the acid. An acid somewhat less concentrate likewise extricates a considerable quantity of calorie, with a good deal of gass; but, as it effects a complete decomposition, it causes Do explosion. An acid diluted with an equal quantity of water, by the aid of a little heat, separates the gass so much less rapidly, that it may with safety be collected in a pneumatic apparatus. But, whatever be the density of the acid (provided no explosion be produced), there remains in the sulphuric liquor, after the separation of the gass, awhite inflammable and uncrystallized powdermixedwith some minute globules of quicksilver.

"To estimate the quantity, and observe the nature, of this uninflammable substance, I treated 100 grains of the fulminating mercury with sulphuric acid a little diluted. The gass being sepa

rated, I decanted off the liquor as it became clear, and freed the insoluble powder from acid by edulcoration with distilled water; after which I dried it, and found it weighed only 84 grains; consequently bad lost 16 grains of its original weight. Suspecting, from the operation of the nitric acid in the former experiment, that these 84 grains (with the exception of the quicksilver globules) were oxalate of mercury, I digested them in nitrate of lime, and found my suspicion just. The mercury of the oxalate united to the nitric acid, and the oxalic acid to the lime. A new insoluble compound was formed; it weighed, when washed and dry,48-5 grains. Carbonate of potass separated the lime, and formed oxalate of potass, capable of precipitating lime-water and muriate of lime; although it had been depurated from excess of alkali, and from carbonate acid, by a previous addition of acetous acid. That the mercury of the oxalate in the 84 grains had united to the nitric acid of the nitrate of lime was proved, by dropping muriatic acid into liquor from which the substance demonstrated to be oxalate of lime had separated; for a copious precipitation of calomel instantly ensued.

"The sulphuric liquor, decanted from the oxalate of mercury, was now added to that with which it was edulcorated, and the whole saturated with carbonate of potass. As effervescence ceased, 3 cloudiness and precipitation followed; and the precipitate being collected, washed and dried, weighed 3-4 grains: it appeared to be a carbonate of mercury. Upon evaporating a portion of the saturated sulphuric liquor, I found nothing but sulphate of potass: nor had it any metallic taste. There then remains, without allowing for the weight of the carbonic united to the 3-4 grains, a deficit from the 100 grains of mercurial powder of 12.6 grains, which I ascribe to the gass separated by the action of the sulphuric acid. To ascertain the quantity, and examine the nature of the gass so separated, I introduced into a very small tubulated retort 50 grains of the mereurial powder, and poured upon it three drachms, by measure, of sulphuric acid, with the assistance of a gentle heat. I first received it over quicksilver: the surface of which, during the operation, partially covered itself with a little black powder. "The gass, by different trials, amounted to from 28 to 31 cubical inches: it first appeared to be nothing but carbonic acid, as it precipitated barytes water, and extinguished a taper, without being itself inflamed, or becoming red. But upon letting up to it liquid caustic ammonia, there was a residue of from 5 to 7 inches of a peculiar inflammable gass, which burnt with a greenish-blue flame. When I made use of the water-tub, I obtained from the same materials from 25 to 27 inches only of gass, although the average quantity of the peculiar inflammable gass was likewise from 5 to 7 inches: therefore, the difference of the aggregate product, over the two fluids, must have arisen from the absorption, by the water, of a part of the carbonic acid in its nascent state. The variation of the quantity of the inflammable gass, when powder from the same parcel is used, seems to depend apon the acid being a little more or less dilute "With respect to the nature of the peculiar inflammable gass, it is plain to me, from the reatons I shall immediately adduce, that it is no other than the gass (in a pure state) into which the nitrous etherized gass can be resolved, by treatment with dilute sulphuric acid.

"The Dutch chemists have shewn, that the nitrous etherized gass can be resolved into nitrous gass, by exposure to concentrate sulphuric acid, and that, by using a dilute instead of a concentrate acid, a gass is obtained which enlarges the flame of a burning taper, so much like the gasseous oxyd of azote, that they mistook it for that substance, until they discovered that it was permanent over water, refused to detonate with hydrogen, and that the fallacious appearance was owing to a mixture of nitrous gass with inflammable gass.

"The inflammable gass separated from the powder answers to the description of the gass which at first deceived the Dutch chemists: 1st, in being permanent over water; 2dly, refusing to detonate with hydrogen; and, 3dly, having the appearance of the gasseous oxyd of azote, when mixed with nitrous gass.

"The gass separable by the same acid, from nitrous etherized gass, and from the mercurial powder, have therefore the same properties. Every chemist would thence conclude, that the nitrous etherized gass is a constituent part of the powder, and the inflammable and nitrous gass, instead of the inflammable and carbonic acid gass, had been the mixed product extricated from it by dilute sulphuric acid.

"It however appears to me, that nitrous gass was really produced by the action of the dilute sulphuric acid; and that, when produced, it united to an excess of oxygen present in the oxalate of mercury.

"To explain how this change might happen, I must premise, that my experiments have shewn me that oxalate of mercury can exist in two, if not in three states. 1st. By the discovery of Mr. Ameilon, the precipitate obtained by oxalic acid, from nitrate of mercury,fuses with a hissing noise. The precipitate is an oxalate of mercury, seemingly with excess of oxygen Mercury dissolved in sulphuric acid and precipitated by oxalic acid, and also the pure red oxyd of mercury digested with oxalic acid, give oxalates in the same state. 2dly. Acetate of mercury, precipitated by oxalic acid, although a true oxalate is formed, has no kind of inflammability. I consider it as an oxalate with less oxygen than those above-mentioned. 3dly. A solution of nitrate of mercury, boiled with dulcified spirit of nitre, gives an oxalate more inflammable than any other; perhaps it contains most oxygen.

"The oxalate of mercury remaining from the powder in the sulphuric liquor is not only always in the same state as that precipitated from acetate of mercury, entirely devoid of inflammability, but contains globules of quicksilver, consequently it must have parted with even more than its excess of oxygen; and if nitrous gass was present, it would of course seize at least a portion of that oxygen. It is true, that globules of quicksilver may seem incompatible with nitrous acid; but the quantity of the one may not correspond with that of the other, or the dilution of the acid may destroy its action.

"As to the presence of the carbonic acid, it must have arisen either from a complete decom. position of a part of the oxalate; or admitting the nitrous etherized gass to be a constituent principle of the powder, from a portion of the oxygen, not taken up by the nitrous gass, being united with the carbon of the etherized gass.

"The muriatic acid, digested with the mercu

globular; snout elongated, inflated, four-jointed; legs ambulatory. Twenty-five specieschiefly of India and South America; a few of Africa and Europe, and one of our own country. The following are the most curious.

1. F. lanternaria. Front extended straight; wing-cases variegated; wings with each a large ocellated spot. This is a very elegant as well as a very extraordinary insect. Its length, from the tip of the front to that of the tail, is nearly three inches and a half; and from wing's end to wing's end, when expanded, nearly five inches and a half. The head is nearly as long as the whole of the rest of the animal; and is the immediate seat of that light for which this insect is so remarkable. The ground colour is an elegant yellow, with a strong tinge of green in some parts, and marked with numerous bright red-brown variegations in the form of stripes and spots: while in the beautiful occllated spot in the lower pair of wings the iris or external circle is scarlet, and the pupil half scarlet and half semi-transparent white.

It inhabits Surinam and other parts of South America; and emits a beautiful and strong phosphoric light from the hollow part of the head. Madame Merian, in her work on the Insects of Surinam, asserts that the light of one of them alone is sufficient to read a common newspaper by: although she does not pretend, as Dr. Darwin has ascribed to her, in the way of poetic licence, in a note subjoined to his poem on the Loves of the Plants, to have drawn and finished her figure of this extraordinary insect by its own light. See Nat. Hist. Pl. CXIX.

2. F. candelaria. Front extended, ascending; wing cases green, spotted with yellow; wings yellow, tipt with black; head and front red, measures nearly two inches in length from the top of the front to the extremity of the tail; and two and a half inches in breadth, with the wings expanded. It is, like the last, a very elegant insect, and like that yields a considerable portion, though, as being smaller, not an equal portion, of intrinsic light. It is a native of China.

3. F. diadema. Front expanded; muricate, trifid at the tip: wings black, edged with red. Inhabits India; and in size and phosphoric powers a rival of the last.

4. F. Europea. Front conic; body green; wings hyaline, reticulate: inhabits Europe; and the only species of the genus that has been found in England. It was the earliest discovered in Europe, and hence its specific name; but this name is now improper, as many others have since been discovered to possess an European origin.

Several of these species are luminous, and especially F. lanternaria, F. candelaria, and F. diadema. The phosphoric splendour, contrary to the physiology of the lampyris, proceeds from its head; and is so strong, that travellers are said to be directed on their journey by fixing one or two of them to the end of a stick." The Indians," says Mad. Merian,

"once brought me, before I knew that they shone by night, a number of these lanthornflies, which I shut up in a large wooden box. In the night they made such a noise that I woke in a fright and ordered a light to be brought, not knowing whence the noise proceeded. As soon as we found that it came from the box, we opened it but were still much more alarmed, and let it fall to the ground at seeing a flame of fire come out of it; and as many animals as came out, so many flames of fire appeared. When we found this to be the case, we recovered from our fright, and again collected the insects, highly admiring their splendid appearance." See LUMINOUS ANIMALS.

FULGOUR. s. (fulgur, Latin.) Splen dour; dazzling brightness (Moore). FULGURATION. s. (fulguratio, Latin.) The act of lightning.

FULHAM. s. A cant word for false dice. (Shakspeare).

FULHAM, a village in Middlesex, four miles W. by S. of London. It is seated on the Thames, and has been the demesne of the bishop of London ever since the conquest.

FU'LICA. In zoology, a genus of the class aves, order grallæ. Bill convex, upper mandible arched over the lower at the edge; lower gibbous near the tip; nostrils oblong, front bald; feet four-toed, subpinnate. These frequent waters, and feed on worms, insects, and small fishes; have a body compressed; bill thick and bent in towards the tip, the upper mandible reaching far up the forehead; wings and tail short. The gallinules have the feet cleft, the upper membranaceous at the base, and the wings concave. The coots have the toes surrounded by a scolloped membrane, the mandibles equal, nostrils oval, narrow and short. Twenty-five species, subdivided as below.

A. Feet cleft: gallinule.
B. Feet pinnate: coot.

We shall offer a specimen or two of each.

1. F. chloropus. Moor-hen. Common gallinule. Front tawny; bracelets red; body blackish, or sooty mixed with olive; beneath cinereous, irids red. Inhabits Europe and America: fourteen inches long; flies with difficulty, but runs and swims well; builds near the water side on low trees or shrubs; strikes with its bill like a hen; lays seven dirty-white eggs twice or thrice a year, thinly spotted with rusty; flesh delicious.

Pur

2. F. purpurea. Crowing gallinule. ple; bill pale; eyes greenish yellow. Inhabits the marshes of New Spain, and crows like a cock.

3. F. porphyrio. Purple gallinule. Front red; bracelets many; body green, beneath violet; head and neck above, glossy violet; cheeks and throat violet-blue; back and rump glossy green; wings and rounded tail shining green, within brown. Inhabits most temperate and warm places; fifteen inches long; is docile and easily tamed; stands on one leg, and lifts the

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