Chapter II (7)

The fulminating silver of Chenevix explodes only by a slight friction in contact with combustible substances. It is nothing more than chlorate of silver. It is formed by passing chlorine gas through alumina, diffused in water, and afterwards digesting, in the liquor, some phosphate of silver. The whole is to be evaporated slowly. A single grain of this powder, with three grains of sulphur, will explode by the slightest friction.

For the preparation of fulminating silver, the formula given by professor Silliman of Yale College, appears to possess some advantages. To an ounce of alcohol and as much nitric acid, he adds 100 grains of pulverized lunar caustic. A gentle heat is applied to excite the action between them, which must be removed, the moment they begin to act. When a thick white precipitate appears, cold water must be added to check the action. The precipitate is then to be collected, washed, and carefully dried. A grain or two will explode over a candle.

_Sect. XXVII. Of Fulminating Gold._

The preparation, called by some aurate of ammonia, is formed by dissolving gold in nitromuriatic acid, diluting the solution with water, and adding gradually liquid ammonia, until the precipitation ceases. The precipitate is then to be caught on a filter, well washed with water, and dried in the air. The fulminating gold, thus produced, exceeds the weight of the original gold employed by thirty-three per cent.

Three or four grains of this powder, heated on a knife, will explode with a loud report. The temperature required for its explosion is between 230° and 300°. Ten or twelve grains will penetrate a copper-plate, of the thickness of a playing card. The facility with which this powder explodes, is increased by drying. If it be heated until it becomes black, the slightest touch will cause a detonation. This powder is composed of oxide of gold, ammonia, and a portion of chlorine; and, during its detonation, water, nitrogen and chlorine are evolved, the gold being revived.

The presence of ammonia is necessary to give to gold the property of fulminating. Fulminating gold accordingly loses this property, the moment the ammonia is separated. Concentrated sulphuric acid, melted sulphur, fat oils, and ether have this effect.

The discoverer of fulminating gold was a German Benedictine Monk, who lived about the year 1413. Basil Valentine has described the preparation of it very accurately. He recommends, however, mixing sal ammoniac with aqua fortis, the old mode of making aqua regia, and distilling the mixture; then putting in the gold in leaf. After the acid is saturated, he adds _oleum tartari_, or _sal tartari_ (carbonate of potassa) dissolved in water; and the precipitated _calx_, thus obtained, when collected, washed, and dried in the open air, will fulminate. In this process, it is evident, that the aqua regia, prepared with sal ammoniac, contains ammonia, and, when the gold is dissolved, and the potash added, the oxide of gold separates, and, from the composition of the powder, must combine with a portion of ammonia, and hence produce fulminating gold. He remarks, that distilled vinegar digested on fulminating gold, destroys its fulminating properties, and observes also, that care must be taken to prevent its explosion. He also knew that sulphur would have the same effect.

Bergman (_Treatise on Pulvis Fulminans_) describes the process employed by Valentine; and Beckman (_History of Inventions_, v. iii. p. 132,) observes, that, after the time of Valentine, Crollius, who lived in the last half of the 16th century, was well acquainted with fulminating gold, and made its preparation more generally known. In the _Oswaldi Crollii Basilica Chymica_, 4to, p. 211, published at Frankfort, in 1609, the process is also to be found. He calls it _aurum volatile_, and speaks of its being useful in medicine. Beguin, however, appears to have given it the appellation of _aurum fulminans_, if we judge from his _Tyrocinium Chymicum_, 12mo, printed in 1608.

_Sect. XXVIII. Of Fulminating Platinum._

While noticing explosive compounds, it may not be improper to mention that of platinum, lately discovered by Mr. E. Davy. It explodes, when heated to 400 degrees, with a sharp report, similar to that produced by fulminating gold; but neither friction nor percussion will decompose it. It is formed by making a solution of platinum in nitromuriatic acid, and passing through it, sulphuretted hydrogen gas, until no further precipitation ensues. This precipitate, when collected, and digested in nitric acid, is converted into sulphate of platinum. This is dissolved in water, and liquid ammonia then added. The precipitate, now formed, is washed, and boiled in a solution of potassa, and, after having freed it from the adhering potassa, is suffered to dry. All fulminating ammoniacal compounds are analogous; and fulminating platinum, being composed of oxide of platinum, ammonia, and water, is decomposed in the same manner as these compounds.

Fulminating platinum is composed as follows:

Peroxide of platinum 82.5 _nearly_ 2 primes.
Ammonia 9.0 1 ----
Water 8.5 2 ----

_Sect. XXIX. Of Detonating Powder from Indigo._

That indigo produces a detonating powder by treating it with nitric acid, is evident from experiment. As it produces a _purple_ light, it might, perhaps, be used advantageously in small fire-works.

The process described by Dr. Thomson, (_System of Chemistry_, VOL. IV. p. 80, _Amer. edit._) is to boil one part of indigo in four parts of nitric acid. The solution will become yellow, and a resinous matter appear upon its surface. The boiling is to be stopt, and the liquor cooled. The resinous matter is then to be separated; and the solution evaporated to the consistence of honey. This is to be re-dissolved in hot water, and filtered, and a solution of potassa added, which will throw down yellow spicular crystals, consisting of _bitter principle_, combined with potassa. When the resin is again treated with nitric acid, the same bitter principle is produced. The spicular crystals, when wrapped up in paper, and struck with a hammer, detonate with a purple light.

_Sect. XXX. Of the Fulminating Compound, called Iodide of Azote._

Iodine is a particular substance, which has the property not only of combining with oxygen and hydrogen, forming iodic and hydriodic acid, but also with various bases constituting a class of bodies, called iodides. Its union with azote produces a singular substance, which detonates with great violence, when slightly touched or heated. It may be formed, by putting a quantity of iodine into the water of ammonia. It will be gradually converted into a brownish-black matter, which is the iodide of azote. It is formed in this process by the iodine, in the first instance, decomposing a part of the ammonia; the hydrogen of which combines with a portion of the iodine, and produces hydriodic acid, which then unites with the undecomposed part of the ammonia, and forms the hydriodate of ammonia; whilst the azote the other constituent of the ammonia, unites with another portion of the iodine, and forms the compound in question.

When exposed to the air, iodide of azote gradually flies off in vapour, without leaving any residue. The products of its detonation are iodine and azotic gas.

The iodide of azote was discovered by M. Courtois, and subsequently examined by M. Colin. Iodine, brought in contact with ammoniacal gas, a combination taking place, produces a viscid shining liquid of a brownish-black colour, which, as the saturation goes on, loses its lustre.

This liquid does not detonate, and is considered to be an iodide of ammonia; but, when it is added to water, it is decomposed, as well as the water, and we obtain two new compounds, as before observed, the hydriodate of ammonia, and iodide of azote. This iodide detonates. Hence it is evident, that hydrogen united with azote, in ammonia, prevents explosion; for the moment it is taken away, by the formation of hydriodic acid, and the azote itself combines with the iodine, a fulminating compound is formed. The elements of this powder are feebly united.

It is found, that hydriodate of ammonia has the property of dissolving a large quantity of iodine, and, if suffered to remain with the iodide of azote, of decomposing it also, and setting the azote at liberty. Water is said to have the same effect, although feebly.

Iodate of potassa, a salt composed of iodic acid and potassa, when mixed with sulphur, and struck with a hammer, will detonate, in consequence of the decomposition of the iodic acid. The iodate of potassa may be formed very readily by agitating iodine with a solution of caustic potassa. The water is decomposed, and the hydriodate of potassa is also formed, which, being very soluble, remains in solution, whilst the iodate separates, on concentrating the liquor, and suffering it to stand.

Chlorate, as well as nitrate of silver, form with sulphur fulminating powders.

Iodic acid, called also oxy-iodine, (prepared by exposing iodine to the action of euchlorine,) when heated in contact with inflammable substances, and the more combustible metals, will produce detonations.

It appears, however, that sulphur has a stronger affinity for oxygen than iodine has, and iodine a stronger affinity than chlorine for the same element. Hence chloric acid is more readily decomposed by inflammable bodies than iodic acid, and iodic acid, sooner than sulphuric acid.

The acids, which chlorine, iodine, and sulphur form respectively with oxygen, Gay-Lussac remarks, have their elements more strongly _condensed_, than the same substances united with hydrogen.

_Sect. XXXI. Of Detonating Oil, or Chloride of Azote._

This oil is produced by the action of chlorine on ammonia, by using some of the salts of this alkali. A small jar of chlorine gas is transferred into a basin, containing a solution of nitrate or muriate of ammonia, a little heated: an absorption will gradually take place, and the gas be condensed. An _oily film_ will now appear on the surface of the ammoniacal solution, which, as it increases, will form globules and fall through the liquor. This substance is the detonating oil, composed, according to analysis, of chlorine, azote, and hydrogen. It is supposed by Messrs. Wilson, Porret, and Kirk, that the hydrogen serves as a medium of union between the chlorine and azote, and that, in detonation, the powerful effect is owing to the chlorine.

Detonating oil explodes violently at 212 degrees; and even when touched with cold inflammable substances, as a portion of olive oil, about the size of a pin's head, the detonation is also violent, and the vessel, in which the experiment is made, will, in most cases, be broken into fragments.

Detonating oil is considered, however, a chloride of azote. In order to prevent the decomposition of the chloride by the ammoniacal salt, a thin stratum of muriate of soda, put into the bottom of the vessel, is recommended. Its specific gravity is 1.653. Warm water, put into a vessel containing it, will change it to an aeriform fluid of an orange colour. "I attempted," says Sir H. Davy, "to collect the products of the new substances, by applying the heat of a spirit-lamp to a globule of it, confined in a curved glass tube over water: a little gas was at first extricated; but, long before the water had attained the temperature of ebullition, a violent flash of light was perceived, with a sharp report; the tube and glass were broken into small fragments, and I received a severe wound in the transparent cornea of the eye, which has produced a considerable inflammation of the eye, and obliges me to make this communication by an amanuensis. This experiment proves what _extreme_ caution is necessary in operating on this substance; for the quantity I used was scarcely as large as a grain of mustard seed." _Phil. Trans._ 1813, Part I.

In _vacuo_, it expands into vapour, which still possesses the power of exploding by heat. In water, it gradually disappears, the water becoming acid, and azote being evolved. Mercury decomposes it, and a white powder (calomel) is formed, while the azote is set at liberty.

Dr. Ure (_Chemical Dictionary_, Art. _Nitrogen_,) observes, that the mechanical force of this compound, seems superior to that of any other known substance, not even excepting the ammoniacal fulminating silver. The velocity of its action appears to be likewise greater.

The Doctor touched a minute globule of it, in a platina spoon, resting on a table, with a fragment of phosphorus at the point of a pen-knife, and the blade was instantly shivered into fragments by the explosion.

Messrs. Porret, Wilson, and Kirk (_Nicholson's Journal_, Vol. XXXIV,) employed 125 different substances, by bringing them in contact; and out of that number the following caused it to explode:

Supersulphuretted hydrogen,
Phosphorus,
Phosphuret of lime,
Phosphuretted camphor,
Camphoretted oil,
Phosphuretted hydrogen gas,
Caoutchouc,
Myrrh,
Palm oil,
Ambergris,
Whale oil,
Linseed oil,
Aqueous ammonia,
Olive oil,
Sulphuretted oil,
Oil of Turpentine,
---- Tar,
---- Amber,
---- Petroleum,
---- Orange peel,
Naphtha,
Soap of silver,
---- Mercury,
---- Copper,
---- Lead,
---- Manganese,
Fused Potassa,
Nitrous gas.

See _Detonating Works_.

According to Mr. Davy, chloride of azote contains
4 vols. of chlorine = 10 + } or { 4 primes = 18.0 +
1 ---- azote = 0.9722 } { 1 ---- = 1.75,
or very nearly 10 by weight of chlorine to 1 of azote.

_Sect. XXXII. Of Pyrophorus._

Pyrophorus is a black substance, which takes fire spontaneously, when brought into contact with air. It is the luft-zunder, or air-tinder of the Germans. It first emits sulphuretted hydrogen gas, and in a few seconds becomes red-hot, burning with a bluish flame. Pyrophorus consists of alumina, charcoal, and sulphuret of potassa, and also, according to some, of potassium, which is alleged to be formed in its preparation. Be this as it may, it seems, that water is decomposed in its combustion, that sulphuretted hydrogen gas is emitted, which is inflamed by the oxygen gas of the atmosphere, and that, during the combination of oxygen, a degree of heat is produced, which causes the ignition of the charcoal, as well as the inflammation of the remaining sulphur.

Pyrophorus may be formed in several ways, all of which produce the same result. The usual process is the following: Take equal parts of brown sugar and alum, and melt them in a ladle. Continue the heat, stirring them constantly until a spongy black mass is formed. Let this mass be reduced at once to powder, and introduced into a common green glass phial, of the capacity of about six ounces, previously coated outside with a mixture of pipe-clay and solution of borax. Immerse the phial in a crucible, filled with sand, closing the mouth of the former with a piece of charcoal, or a glass tube inserted in it. Upon the crucible being exposed to a red heat, an inflammable gas will escape, which will take fire.[21] When this effect ensues, the heat must be continued for about twenty minutes longer, at the expiration of which time, the crucible must be removed from the fire, and the phial taken out and closely stopt. The pyrophorus is to be preserved in a ground stoppered bottle. The addition of one-sixteenth part of sulphate of soda, or Glauber's salt, to the alum and sugar, is said to make the pyrophorus with more certainty. Various vegetable substances, besides sugar, as flour, starch, &c. may be used. Three parts of alum, and one part of wheat flour will make a good pyrophorus.

Homberg discovered this substance, in the year 1680. Hence it is sometimes called Homberg's pyrophorus. He was operating upon a mixture of human excrement and alum; and, when he examined the contents of his vessel, in three or four days after, he was surprised to see it take fire spontaneously, when brought to the air. Soon after Lemery, the younger, discovered, that honey, sugar, flour, or almost any animal or vegetable matter, could be used in lieu of human fæces; and, as Macquer informs us, M. Lejoy de Suvigny showed, that other salts, containing sulphuric acid, may be substituted for alum. Mr. Scheele (_Treatise on fire_, &c.) found by experiment, that, when alum was deprived of potassa, it was incapable of forming pyrophorus, and that vitriolated tartar (sulphate of potassa) may be used in the place of alum. The experiments of Mr. Proust prove, that a number of neutral salts, composed of vegetable acids and earths, when submitted to heat, leave a residuum that inflames spontaneously. This statement agrees with the experiments of M. Chenevix. From the experiments and observations of sir H. Davy, and Dr. J. R. Coxe, late professor of chemistry, but now of materia medica, &c. in the University of Pennsylvania, it is rendered very probable, that pyrophorus owes its property of inflaming spontaneously to a small portion of potassium, which is formed in the process.

The preparation of pyrophorus is explained on the principle, that the vegetable matter is first decomposed; that the hydrogen and a part of the carbon decompose the sulphuric acid of the alum, by uniting with its oxygen; that water, carbonic oxide, and carburetted hydrogen are disengaged, along with a part of the sulphur; and that, while the excess of charcoal remains intimately mixed or divided with the alumina, the sulphur and the sulphuret of potassa, form together a compound, which has the property of inflaming spontaneously in the open air. Some suppose, as alum is a triple salt, having potassa, as well as alumina, for its base, that the potassa is decomposed in the process, and potassium, as we remarked, produced; to the presence of which they ascribe the singular property of inflaming in the open air.

The spontaneous combustion of charcoal, in several instances, is supposed by some to have been owing to the presence of pyrophorus, by others to phosphorus, and by others again to nascent hydrogen. To the presence of this substance, is attributed the explosion of gunpowder mills. (See _Gunpowder_.)

Several different mixtures, and torrefied substances, form a kind of imperfect pyrophori, and have more than once occasioned fires, from no suspicion of their properties being entertained.

Besides pyrophorus, other compositions, which, in like manner, take fire on exposure to the open air, have been by degrees made known to us: 1. The scoria of the martial regulus of antimony, or antimony freed from sulphur by the intervention of iron and nitre, as well crude as also after being dissolved, have been observed to take fire spontaneously, when laid upon a hot stone, or in the sun. Of the truth of the latter case, Wiegleb says, he is assured by his own experience. 2. The residuum of the acetate of copper is another pyrophorus. 3. Some assert, that they have observed an inflammation ensue from honey and flour, calcined according to the rules laid down. 4. According to Geoffroy, a calcined mass of three parts of black soap, and one of diaphoretic antimony, has been known to take fire spontaneously. 5. Meuder has observed, that a pyrophorus is obtained, when equal parts of orpiment and iron-filings are sublimed together, and ten parts of this sublimate are triturated in a mortar along with twelve of nitrate of silver. 6. A pyrophorus is produced, according to Penzky, when two drachms of white sand, three of common salt, one of sulphur, two of sulphuric acid, and half an ounce of muriatic, are mixed together and distilled in a glass retort. In this operation, a sublimate is said to be obtained, which bursts out in flames, as soon as it comes into contact with the air. 7. The spontaneous precipitate of osteocolla, from a solution of it in sulphuric acid, after having been separated by means of a filter, and dried, took fire in a warm place. S. Pott observed the same phenomenon in the earth of the residuum, after the distillation of urine, that had been putrid for a considerable time. 9. To these may also be referred, a mass composed of equal parts of sulphur and iron-filings; which, when thoroughly moistened with water, after some time, grows hot, swells, and at last breaks out into vapour, smoke, and flame. (See _Artificial Volcano_.)

Cadet's fuming liquor, prepared by distilling equal parts of acetate of potassa, and arsenious acid, emits a very dense, heavy, fetid, noxious vapour, which inflames spontaneously in the open air. Black wadd, an ore of manganese, when dried by the fire, and mixed with linseed oil, gradually becomes hot, swells, and then bursts into flame.

M. Chenevix (_Annales de Chimie_, tom. LXIX,) remarks that almost all the metallic residuums, which are formed by the distillation of acetates _per se_, are pyrophoric, after cooling; which Mr. C. attributes to the presence of finely divided charcoal, mixed with the metallic part. He experimented on several acetates, with the view of ascertaining the quantity of pyroacetic spirit they would yield, and found, in every instance, that charcoal existed in the residue, sometimes with reduced metal, and at other times with metallic oxide. A table of these experiments may be seen in Ure's _Chemical Dictionary_. The residuum of acetate of copper has long been known to possess pyrophoric properties.

_Sect. XXXIII. Of Sal Ammoniac._

This salt enters into the composition of fire-works, to give, more particularly, a peculiar colour to flame, which is that of green, or yellowish-green. Sal ammoniac is a salt, composed of muriatic acid and ammonia, and, when pure, is white, and capable of being sublimed without decomposition. Its purity may be known by its complete volatilization. It is readily pulverized.

The experiment, showing the formation of sal ammoniac by a direct union of its component parts, may be made by bringing in contact, in a glass receiver, muriatic acid gas and ammoniacal gas. White clouds will form, a condensation take place, and muriate of ammonia be deposited on the sides of the vessel.

Sal ammoniac was altogether made, at one period, from the soot of camels' dung, or of other animals, which feed on saline plants. The excrement was burnt, the soot collected, and sublimed. This was the process practised in Egypt. The composition of sal ammoniac being known, the process for obtaining it was improved; so that, instead of using the soot of dung, it is now formed by the distillation of bones. The impure ammoniacal liquor, thus obtained, is combined with sulphuric acid, by an easy process, and the resulting sulphate of ammonia is then decomposed by muriate of soda, by which sulphate of soda and muriate of ammonia are produced. They are separated, and the latter is formed into heads by sublimation. In this state, it occurs in commerce. It was made in great quantity in the vicinity of the temple of Jupiter Ammon; and hence its name.

Mr. Minish, according to the English writers, is entitled to this method of converting impure liquid ammonia into sal ammoniac. The following is an outline of his process. He suffered the impure ammoniacal liquor to percolate through a stratum of bruised gypsum, and as carbonate of ammonia is contained in the liquor, the fluid, which filters, would contain sulphate of ammonia, the carbonate of lime being insoluble. This sulphate he evaporated, and the dry mass, mixed with muriate of soda, was sublimed. If I am not greatly mistaken, however, although I have not the work to refer to, this process is described in Dr. John Pennington's _Chemical Essays_, a work published in Philadelphia, about 1792. Dr. Pennington's work, we may observe, is the first chemical book which was published in the United States, and contains numerous important facts and observations. That this process was known in Philadelphia, and used at the _Globe works_, or rather _Glaub works_, (from the circumstance that Glauber's salt was made there,) is within the recollection of many. I heard the late professor Wistar speak of this process, and of the economy in using gypsum.

Mr. Lebanc (_Annales de Chimie_, vol. XIX.) invented a process, by which he brought the ammoniacal gas and muriatic acid gas in contact, in a chamber lined with lead. In one pot, he put common salt and oil of vitriol; in another pot, animal matter. Being conducted by pipes into the chamber, the gases united, and sal ammoniac was formed. Other improvements have been made, as obtaining ammonia from coal soot, &c.

Ammonia is generated in artificial nitre beds, and is at first united with nitric acid; which compound is subsequently decomposed, as the process of putrefaction goes on, by the potassa, calcareous earth, &c. present in nitre beds. _See Nitrate of Potassa._

Sal ammoniac is ready formed in the soot of animal feces, twenty-six pounds of which yield six of the salt. According to Siccard, who published, in 1716, an account of the fabrication of sal ammoniac in Egypt, which Geoffroy, in the same year, proved to be a compound of the spirit of sea salt and volatile alkali, sea salt and urine were used in that country. The account, however, given by Lemery, in 1719, makes no mention of either sea salt or urine.

Sal ammoniac is found native. It occurs in the vicinity of burning beds of coal, both in Scotland and England, and is met with in volcanic countries. When triturated with quicklime, it exhales ammonia, which is a characteristic of all ammoniacal salts.

Sal ammoniac is often found in crusts of lava. Sir William Hamilton observes, that, in the fissures formed by the lava, this salt sublimes. He found, in the same locality, common salt.

Sal ammoniac is decomposed by a variety of substances. Sulphuric acid will disengage the muriatic acid from it, while lime, potassa, &c. liberates the ammoniacal gas, which, when combined with water by distillation or other means, forms the common spirit of sal ammoniac, or water of ammonia. Mixed with carbonate of lime and sublimed, it produces the carbonate of ammonia, usually called mild volatile alkali, or pungent smelling salts. Ammonia, in a separate state, unites with some metallic oxides, giving rise to certain fulminating powders, which have been already noticed. That iodine decomposes ammonia, we have shown, when on the preparation of iodide of azote, or fulminating powder.

Sal ammoniac enters into the composition of candles, to prolong their duration. The process recommended in the _Archives des Découvertes_ is the following: Dissolve, in half a pint of water, a quarter of an ounce of sal ammoniac, two ounces of common salt, and half an ounce of saltpetre, and add the solution to three pounds of mutton tallow, and eight pounds of beef tallow, previously melted. Continue the heat until all the water is evaporated. It is then suffered to cool, and, when used, is to be melted with a quarter of an ounce of nitre, and formed into candles in the usual manner. This preparation of tallow is highly recommended on account of its economy, as well as the improvement itself. A candle, made of this tallow, will burn two hours longer than one of the ordinary kind.

Another process for making candles, in which sal ammoniac is used, is mentioned in the _Annales des Arts et Manufactures, Nos. 142 and 146_. Eight pounds of suet are melted, and a pint of water is added. The tallow is again submitted to heat, and the same quantity of water, holding in solution half an ounce of saltpetre, half an ounce of sal ammoniac, and one ounce of alum, is added. It is then suffered to stand, and when used is re-melted. The wick is first dipped in a mixture of camphor and wax. Care must be taken, before the tallow is used, to evaporate the water. Equal parts of beef and mutton tallow are recommended.

_Sect. XXXIV. Of Corrosive Sublimate._

Corrosive sublimate, known in chemistry by the names of corrosive muriate, and perchloride of mercury, is made use of in some preparations of fire-works, and particularly in the composition of stars, in which it is mixed with a variety of substances, such as steel filings and antimony, in order to vary the appearance of the flame, and to communicate to it particular colours. Corrosive sublimate is formed by various processes, among which we may enumerate the following: Take five parts of sulphuric acid, four parts of mercury, four parts of muriate of soda, and one part of black oxide of manganese. Boil the mercury in the sulphuric acid, until it forms a dry sulphate, which is to be reduced to five parts. Mix the sulphate thus formed, with the muriate of soda, previously dried, and the oxide of manganese, and sublime the mixture. By this process the sulphuric acid of the sulphate unites with the soda, and forms sulphate of soda; while the muriatic acid of the muriate of soda combines with the oxide of mercury, (which receives an addition of oxygen from the oxide of manganese,) and forms the perchloride, called by Thenard the deutochloride of mercury. The same process is used without the addition of manganese. By exposure to heat, the sublimate sublimes, and the sulphate of soda forms the residuum. The same salt, if re-sublimed with an addition of crude mercury, will be changed into the protochloride of mercury, or calomel. Or, if the sulphate of mercury and muriate of soda be mixed with crude mercury, and sublimed, calomel will be formed at one operation. It is sufficient to observe, that corrosive sublimate is one of the most virulent of poisons when swallowed; and therefore should be used with caution.

It is soluble in water, and capable of crystallizing. It is also soluble in alcohol, to the flame of which it communicates a yellow colour, and in sulphuric, nitric, and muriatic acids. It is decomposed by alkalies, forming with ammonia a triple salt, (_Sal Alembroth_,) by the alkaline earths, and the metals or their sulphurets; and, when distilled with arsenic, bismuth, antimony, or tin, the mercury is separated.

The proper antidote for corrosive sublimate, is the white of egg or albumen, which converts it into calomel. Sulphuretted hydrogen water may also be employed along with emetics. The effect of albumen, in this way, may be relied on.

_Sect. XXXV. Of Orpiment._

Orpiment, or the yellow sulphuret of arsenic, which is either native or artificial, is principally used in fire-works for the composition of stars. Orpiment is divided by some into two kinds; viz. the red, called realgar, and the yellow, called yellow arsenic.

Arsenic combines readily with sulphur. When they are mixed together, and put into a crucible and fused, the product will be a red vitreous mass. This red sulphuret may also be formed, by melting sulphur with arsenious, or arsenic acid. Sulphurous acid gas will be evolved, evidently showing that a portion of the sulphur unites with the oxygen of acid employed.

When arsenious acid, known in commerce by the name of white arsenic, and called by some oxide of arsenic, is dissolved in muriatic acid, and a solution of sulphuretted hydrogen in water is added, a yellow precipitate will be obtained which is orpiment. The hydrogen, in this case, unites with the oxygen of the arsenious acid, by which the metal is reduced, and the sulphur then combines with it. A mixture of sulphur and arsenic, exposed to a heat not sufficient to melt them, will sublime into a yellow sulphuret.

Both the yellow and red sulphurets are employed in fire-works. They are not, however, required, except in particular cases. In the composition of Bengal lights, given in the Bombardier or Pocket Gunner, by R. W. Adye, orpiment is used. According to the same author, it is also used in Chinese white lights. Both the yellow and red sulphuret of arsenic will detonate with chlorate of potassa.

_Sect. XXXVI. Of Antimony._

The antimony, which enters into the composition of many fire-works, is not to be understood to be the metallic, or regulus of, antimony, unless so expressed; but the crude antimony of the shops. Crude antimony is a combination of antimony and sulphur, and is usually met with in fine powder. That both antimony and its sulphuret have a powerful effect in modifying the flame of gunpowder, and all compositions, in which nitre and inflammable substances form a part, is evident from the many cases, in which it is employed, and from the effects that thereby result.

The different substances in any inflammable compound, intended to produce particular colours, should be so mixed, as that, from a knowledge of the proportions which produce such colours, the _effect_ may be retained, even when it is mixed with other bodies. For this reason, the artist should know the different effect of each ingredient. Some may show themselves in the flame, some in sparks, some in stars, others in fire-rain, and the like, as the case may be. Antimony, for instance, produces a reddish flame, if it be in a proper proportion, and not altered by the presence of other substances. Hence, when antimony is mixed with nitre, the flame will be more or less a _whitish-green_.

This modification, or change in the appearance of flame, is apparent in certain compounds, of which antimony constitutes a part. Thus, antimony is used in the preparation of the common rocket stars, in drove stars, in the fixed pointed stars, in some of the gold and silver rains, in the slow and dead fire for wheels, in tourbillons for crowns or globes, in the composition of serpents, lances for illumination, Bengal lights, and many other kinds of fire-works. According to Adye, (Pocket Gunner,) it enters into the composition of carcasses, Chinese lights, &c.

When it is as one to sixteen of nitre, the gunpowder being as four, and the sulphur, eight, the composition will produce a white flame; but when it is in the proportion of eight to sixteen of nitre, without any addition, the flame will be blue. By substituting, in its place, eight of amber to sixteen of nitre, with sixteen of sulphur, and eight of meal powder, this change will produce a yellow flame. It is obvious, however, that these and similar changes are owing to the proportions, as well as to the substances used.

Antimony, in the state of a sulphuret, when mixed with chlorate of potassa, &c. will form detonating compounds.

Antimony is a grayish-white metal, more or less brilliant and laminated. It is brittle, and may be easily reduced to powder. It melts at a red heat, and evaporates at a higher temperature: on cooling, it crystallizes. It undergoes no change by exposure to the air, except the loss of its lustre. When steam is made to pass over ignited antimony, the decomposition of the water is so rapid, as to produce a violent detonation. At a white heat, it burns, and forms a white coloured oxide, called the _argentine flowers of antimony_. Its oxides are various, some of which, possessing acid properties, are called acids. The protoxide is gray, the antimonious acid, white, and antimonic acid, of a straw colour. The crocus of antimony, and the glass of antimony are oxides of this metal, but in particular states of combination. It unites with several of the acids. Its oxide, with tartaric acid, and tartrate of potassa, forms _tartar emetic_. With chlorine, it constitutes the butter of antimony.

The artificial sulphuret may be formed, by melting sulphur and antimony together. The native sulphuret is almost the only ore of antimony, and is the mineral from which the regulus is obtained. It unites with the metals, forming alloys of different kinds.

_Sect. XXXVII. Of Carbonate of Potassa._

Potassa, either pure or carbonated, retards the progress of combustion; and, therefore, may prevent, according to the proportion employed, the action of combustible bodies on nitre. Combustion may be retarded by using those substances, which are not in themselves inflammable, and which, if used in too large a quantity, would effectually prevent it. Clay, wood ashes, &c. as in the blind fuse, act on this principle; and serve, also, in particular cases, to produce that succession of explosions, which renders the effect of some fire-works, more grand and impressive. Rope, soaked in a solution of saltpetre and dried, would burn rapidly, were it not for the after immersion in potash ley, or urine, either of which acts by retarding the progress of combustion. The same thing may be said of other bodies, the use of which will claim our attention hereafter. Potassa, although not generally used for the purposes mentioned, as it is apt to deliquesce, or absorb water, and thus destroy the effect altogether, may be more advantageously employed in a liquid state, as in the preparation of slow match in the way stated under that head. But as match rope is now generally superseded by the port-fire, as a more certain method of firing cannon, it would be unnecessary, as it is irrelevant, to enlarge on this head. The use, also, of the priming fuse, which conveys the fire to the powder in the gun, with certainty and with rapidity, is an improvement of no small moment.

Alum has also been used for the purpose of checking the rapidity of combustion, in some particular fire-works. In one of the formulæ for the preparation of _fire-balls_, to be thrown with the hand, or fired from a gun, given in the _Memoir on Military Fire-works_, as taught at Strasburg, in 1764, there is, besides sulphur, mutton suet, saltpetre, and antimony, _nitre of alum_, equal to one-fourth of the weight of the compound. That this salt, the supersulphate of alumina and potassa, is used to make paper, as cartridge paper, &c. incombustible, is a fact, with which every one is acquainted.

We might, also, enumerate the uses of glue, isinglass, gum arabic, &c. for similar purposes; and also of wood-ashes, in the composition of the, so called, blind fuse. Light twisted white rope, when soaked in strong ley, or a strong solution of potash, we are informed, will form a slow match that will burn only three feet in six hours.

Potash is obtained from wood-ashes, by lixiviation with water, and evaporation. It contains more or less impurities; and always carbonic acid, from which it is separated by quicklime, the alkali being rendered caustic. Some of the foreign ingredients are burnt off by exposing it to heat in an oven. It then assumes a white, somewhat _pearly_ appearance, and takes the name of pearl-ash, but is still the same alkali.

Wood-ashes, when mixed with quicklime, and lixiviated, produce caustic ley, the strength of which depends on the quantity of alkali held in solution. It is this ley, when boiled with oils, fat, &c. that produces soft soap. Hard soap is a combination of oil or fat, and soda. The quantity of real alkali in potash may be known by the proportion of acid required to saturate a given weight of it. Potash, pearl-ash, salt of tartar, and salt of wormwood are all carbonates of potassa. This alkali is called the vegetable alkali, because it is obtained from vegetables. It is considered to be the hydrated deutoxide of potassium, and when decomposed will furnish potassium.

_Table of the saline or soluble products of one thousand pounds of ashes of the following vegetables._

SALINE PRODUCTS.

Stalks of Turkey wheat, 198 lbs.
Stalks of sun-flower, 349
Vine branches 162.6
Elm 166
Box 78
Sallow 102
Oak 111
Aspen 61
Beach 219
Fern, cut in August, 116, or 125 according to Wildenheim.
Wormwood 748
Fumitory 360
Heath 115

The observations of Mr. Kirwan on potash may be seen in _Aikin's Chemical Dictionary_.

When a piece of hydrated potassa is placed between two disks of platinum, which are brought in contact with the poles of a galvanic battery, consisting of upwards of 200 pairs of plates, four inches square, the oxygen will separate at the positive surface, and small metallic globules of potassium will be formed at the negative surface. The potassa, in the mean time, will undergo fusion.

Sir H. Davy discovered potassium, in 1807. It may be obtained by means of iron turnings, in the following manner: Heat the iron turnings to whiteness in a curved gun barrel, and suffer potassa, in a state of fusion, to fall upon them very gradually, air being excluded: potassium will form, and collect in the cool part of the tube. For the different facts respecting this metal, consult Sir H. Davy's communications on the subject, and the memoirs of Gay-Lussac and Thenard, Curadeau, &c. See also, Davy's _Chemical Philosophy_, and Thenard's _Traité de Chimie_.

Potassa unites with, and neutralizes, acids, and forms salts; the principal of which are the sulphate, muriate, and nitrate of potassa. It unites also with sulphur, phosphorus, &c.

Potassa, in the state of carbonate, is very soluble in water, for which it has so strong an affinity, that, when exposed to the atmosphere, it deliquesces and becomes fluid. Caustic potassa undergoes the same change, in a more remarkable degree. It is on account of its great avidity for water, that the carbonate is used in the preparation of alcohol from spirituous liquors; it retaining the water, while the alcohol may be distilled over.

Potassa has a stronger affinity for the acids, than either the earths or metals; hence it decomposes earthy and metallic salts, the earth or metallic oxide being precipitated, while it unites with the acid of the salt. It is on the same principle, that earthy and metallic salts decompose soap; and waters which are hard, and owe that property to the presence of earthy salts, will curdle, or, in other words, decompose soap. Such waters, for this reason, are called hard. Acids have the same effect in decomposing soap.

The use of potassa is very apparent in the manufacture of saltpetre. When the nitric acid is combined with an earthy base, as in the calcareous nitre of the nitre caves of the western country, potassa from wood-ashes will decompose it, on the principle already stated; and, by combining with the nitric acid, form nitrate of potassa. It is used also in refining saltpetre, where earthy salts are present, besides common salt. The effect of this alkali, for that purpose, will be more obvious, by referring to the processes for the extraction and refining of saltpetre, in the article on that subject.

Potassa acts as a flux for siliceous substances and forms glass. These are its prominent characters.

_Sect. XXXVIII. Of Wood-Ashes._

Wood-ashes, the product of the combustion of wood, contain potassa, some foreign salts, and earthy and sometimes metallic substances, insoluble in water. The quantity of alkali, which ashes, obtained from different woods, furnish, is greater or less, according to the nature of the wood. The ashes of the oak are generally used in pyrotechny; but it seems to us, that ashes in common will have the same effect.

The ashes, for this purpose, should be dry, and passed through a fine sieve. They enter into the composition of blind fuse.

In some instances, the _leached_, or lixiviated ashes might be used. The residue, after the separation of alkali and saline matter by the action of water, is nothing more than the insoluble part of the ashes. Caustic ley is always obtained from wood-ashes, by mixing them with about a fiftieth part of quicklime, and putting them into a barrel or tub, and adding water. The lime takes up the carbonic acid, and the ley comes off in a caustic state. If the solution should not contain a sufficient quantity of potassa, or not bear an egg, as that is the usual criterion of its strength, (which depends on its specific gravity,) its strength may be increased by evaporation; and, if too strong, simple dilution with water, is all that is necessary.

While the ashes of some plants, as the upland plants, generally yield potassa; others, as many marine plants, the _salicornia europea_, _salsola tragus_, _salsola kali_, _&c._ afford soda by incineration. It will be sufficient, however, to observe, that the ashes of all plants contain alkali, in more or less quantity, which depends on various circumstances; and that the alkali may be extracted by lixiviation, and, in some instances, may even be seen among the ashes, in a semivitrified mass. The white ashes, which are formed by the combustion of animal matter, as osseous or bony substances, we may remark, do not afford potassa or soda, but only phosphate of lime, and some uncombined earths. Bones, nevertheless, may, like wood, be carbonized, although the charcoal formed is of a different nature. For the preparation of phosphorus from bone-ash, see the article Phosphorus.

_Sec. XXXIX. Of Clay._

Clay is an argillo-siliceous substance, of a colour more or less yellow, and containing a variable quantity of silica and alumina, with oxide of iron. There are a variety of clays; the common potter's clay, pipe clay, porcelain clay, &c. Some contain, and others are free from iron. Those that contain this metal burn _red_; while those which remain, or become white in the process of burning, are free from it.

The use of clay in fire-works is confined nearly altogether to rockets. In the driving of sky-rockets, &c. the _charge_ must always be driven one diameter above the piercer, and on it there is sometimes rammed one-third of a diameter of clay, through the middle of which a hole is bored to the composition, so that, when the charge is burnt to the top, it may communicate its fire through the hole, to the stars in the head. This, however, is not always the case. See _Rockets_.

The clay for fire-works, is usually prepared of the common kind, which contains neither stones nor sand. It must be first baked in an oven, until perfectly dry, and then pulverized, and sifted through a common hair sieve. In China, the Chinese mostly employ, for this purpose, their white porcelain clay.

_Sec. XL. Of Quicklime._

Lime, as it is found in nature, is combined with carbonic and sulphuric acids, and less frequently with some of the other acids, as the nitric, fluoric and phosphoric. Calcareous carbonates are the most abundant; in which we include marble, limestone, and chalk; and the sulphate, or gypsum, may be considered the next. Lime constitutes the basis of marine shells; for, when burnt, they furnish quicklime. Its union with nitric acid is well known, forming the calcareous nitre of the saltpetre caves of Kentucky, &c. We have mentioned this combination under the head of nitre.

Without enumerating all the chemical properties of lime, it will be sufficient to remark, that it is composed of calcium and oxygen, and, when slaked with water, will evolve caloric in a free state, while the water solidifies or combines with the lime; that it forms with water, a solid hydrate, an example of which combination is afforded by the preparation of mortar; that it dissolves in water, and forms lime-water, and is slaked by exposure to the air, absorbing, at the same time, carbonic acid; that it unites with acids, like other salifiable bases, and forms salts, some of which are soluble in water, and others not; that it deprives the alkalies of carbonic acid, and renders them caustic, being itself changed into a carbonate; and, that it unites with sulphur and phosphorus, forming a sulphuret and phosphuret, and, also, with hydroguretted sulphur, and sulphuretted hydrogen, forming a hydroguretted sulphuret, and a hydro-sulphuret.

When limestone, marble, &c. are burnt in a kiln, the carbonic acid is expelled, and quicklime formed. Quicklime and lime, chemically speaking, are synonimous terms.

The fluor, or Derbyshire spar, is a fluate of lime. When this substance is distilled in a leaden retort, with sulphuric acid, we have sulphate of lime, and fluoric acid gas, called by some hydro-fluoric acid. This acid, when received in water, is used to etch on glass, in the same manner as nitric acid on copper; and while applied in a liquid state, or in that of gas, it acts on the glass, by combining with the silicon, and is changed from the hydrofluoric, into the silicated fluoric acid. If, instead of employing a leaden vessel, we make use of a glass retort, or introduce powdered glass or silica, into the leaden vessel, in either case, we obtain another acid, which we have just mentioned, the silicated fluoric acid; in consequence of the union of silicon with the supposed radical of the fluoric acid, known by the name of fluorine.

Quicklime is occasionally, though but rarely, employed in fire-works. That it increases the strength of powder, is asserted by Dr. Bayne. See Gunpowder. Its use in making slow match, along with other substances, is given in the article on that subject.

_Sec. XLI. Of Lapis Calaminaris._

That some of the ores of zinc are employed in fire-works, is evident from the use of lapis calaminaris, or calamine stone, which is an impure carbonate of zinc. Calamine should be finely pulverized and sifted. As zinc gives a particular colour to flame, (see _zinc_), its carbonate may also communicate a colour, and, under particular circumstances, may produce a great variety, and, therefore, in such cases, be preferable to the zinc itself. It is one of the ingredients in the _dead fire_ for wheels, which is composed of lapis calaminaris, saltpetre, brimstone, and antimony.

The modifications, to which particular bodies are subject, as to their respective effects, depend very greatly on the presence of other bodies, and frequently on the chemical action, which ensues throughout; so that, as we had occasion to observe, the _effect_ which one body would produce on the flame, maybe completely changed, modified, or varied by the presence of a second, third, or fourth substance. The art, therefore, of uniting various bodies, in kind, as well as in proportion, so as to produce a given effect, can be acquired only by a series of experiments. Zinc, as a metal, when finely divided, produces a peculiar effect; when mixed with other metals, and with certain salts, as sal ammoniac, another; and, when combined with some acids, as the carbonic in lapis calaminaris, a third effect; and these effects may be governed, as it appears, by the presence or absence of certain bodies. This fact will appear more striking, when we consider the various mixtures, and their respective properties. For the uses of zinc, see that article.

_Sec. XLII. Of Zinc._

Zinc, commonly called spelter, is a metal, obtained from blende, or sulphuret of zinc, and calamine, or carbonate of zinc. The ore is first roasted, and then mixed with some carbonaceous flux, and submitted to the action of heat in close vessels. The metal is volatilized, and passes over, and is usually caught in water. It is then fused, and cast in moulds.

Zinc possesses many remarkable properties, some of which are the following. It is of a brilliant white colour, with a shade of blue, and is composed of a number of thin plates, adhering together. Its specific gravity is more than six times that of water. It is brittle, but, when heated to 212 degrees, may be hammered out, or made into sheets. At 400° it becomes very brittle. Its tenacity is so feeble, that a wire of 1/10th of an inch in diameter, will support a weight of only 26 pounds. At 680° it melts, and above that temperature, evaporates. It soon oxidizes, and its lustre is therefore tarnished. At common temperatures, it soon decomposes water; and, when the vapour of water is passed over it at a high temperature, the decomposition is very rapid, the oxygen of the water being absorbed. Zinc is soon oxidized when melted and exposed to the air, forming a gray oxide.

At a red heat, zinc inflames, and the product of combustion is the white oxide of zinc, or flowers. The oxide of zinc is reduced by mixing it with charcoal, and exposing the mixture to a strong heat in close vessels.

Zinc will burn in chlorine gas, and forms a chloride of zinc. If the perchloride of mercury and zinc-filings be heated together, the same compound will result. This chloride melts at 212°, and rises, in the gaseous form, at a heat much below ignition. It was formerly called the _butter of zinc_, and muriate of zinc. With iodine, zinc forms a compound, called iodide of zinc.

With phosphorus and sulphur, zinc also combines, and with the latter, it forms the native sulphuret, known by the name of blende. It unites, also, with acids, and forms salts. Of these, the sulphate of zinc, or white vitriol, is the most common. It unites with various metals, forming alloys. Of these, that with copper, called brass, is the most known. Zinc, with copper, forms galvanic batteries. With tin and mercury, it constitutes amalgam for electrical machines. It forms, besides brass, the yellow copper, or laiton; commonly called pinchbeck.

Acetic acid readily dissolves zinc. The acetate formed is not altered by exposure to the air, is soluble in water, and burns with a _blue_ flame. It may be used, therefore, in fire-works, to communicate that colour to flame. It may be formed very expeditiously, by mixing about equal parts of sulphate of zinc, and acetate of lead, both being in solution. The sulphate of lead, which is formed, will precipitate, and acetate of zinc remain in solution. By evaporation, it is obtained in crystals. This salt cannot injure any composition of fire-work, in which it enters; as it does not deliquesce, and, for that reason, may be advantageously employed.