Neither Diaphoretic Antimony nor the Pearly matter are soluble in any Acid.

PROCESS VIII.

It frequently happens, when we employ a calx of Antimony which is not sufficiently deprived of its phlogiston, that we find in the crucible a button of Regulus, which, being heavier than the Glass, always lies at the bottom. With a view to avoid this inconvenience, and to dissipate completely the excess of phlogiston that may still be left in the calx of Antimony, we direct the crucible to be left uncovered for some time, at the beginning of the operation. If, notwithstanding this precaution, any Regulus be still found at the bottom of the crucible, and you resolve to vitrify it, the crucible must be returned to the furnace, and the fusion continued; by which means the Regulus will at last be converted into Glass.

If, on the contrary, you meet with any difficulty in effecting the vitrification, on account of your having employed a calx that hath lost too much of its phlogiston, such as Diaphoretic Antimony, or the Pearly matter, the fusion may be greatly facilitated by throwing into the crucible a little crude Antimony.

Glass of Antimony is a most violent emetic. This Glass, as well as Liver of Antimony, is employed in preparing Emetic Wine and Emetic Tartar.

It may be resuscitated, like the calces of Antimony, into a Regulus, by re-uniting it with a phlogiston. For this purpose it must be finely pulverized, thoroughly mixed with some black flux, and melted in a covered crucible. This Glass, as well as that of Lead, hath the property of greatly promoting the vitrification of matters that are to be scorified.

PROCESS IX.

Return your Antimony into the coffee-pot. Pour on it as much rain-water as before, and three fourths of the former quantity of the liquor of Fixed Nitre. Boil it again for two hours, and then filter the liquor. It will again deposite a red sediment. Return your Antimony into the coffee-pot: pour on it the same quantity of rain-water, and half the first quantity of the liquor of Fixed Nitre. Boil it again for two hours, and then filter the liquor as formerly. Wash all these sediments with warm water, till they become insipid; then dry them, and you have the Kermes Mineral.

OBSERVATIONS.

If you recollect what we said concerning the property which Fixed Alkalis possess of uniting with Sulphur, both by fusion, and, when those Salts are resolved into a liquor, by boiling, and of forming therewith a Liver of Sulphur, which dissolves all metalline substances, you will readily comprehend the nature of this Kermes.

Antimony consists of a sulphureous and a reguline part. Therefore, if this mineral be boiled in a solution of a Fixed Alkali, such as Nitre fixed by charcoal, the Alkali will dissolve the Sulphur of the Antimony, and form therewith a Liver of Sulphur, which, in its turn, will dissolve the reguline part. Now, Kermes Mineral, prepared as above directed, is no other than a Liver of Sulphur combined with a certain quantity of Regulus of Antimony.

Mr. Geoffroy hath set this truth in the clearest light, by his accurate analysis of the Kermes Mineral. The experiments he made on that subject are circumstantially related in several Memoirs printed in the volumes of the Academy for 1734 and 1735. By combining Acids with the Kermes he demonstrated, 1. the existence of Sulphur in this compound; having separated from it a burning Sulphur, which cannot be mistaken for any other than the Sulphur of Antimony. In order to obtain this Sulphur pure, an Acid must be employed that will not only absorb the Alkali, but also perfectly dissolve the reguline part that might otherwise remain united with the Sulphur. Aqua regia was the Acid which succeeded best with Mr. Geoffroy. 2. He also proved that there is a Fixed Alkali in the composition of the Kermes; seeing the Acids with which he precipitated the Sulphur became Neutral Salts, and just such as those very Acids combined with a Fixed Alkali would have constituted: that is, the Vitriolic Acid produced a Sal de duobus; the Nitrous Acid a regenerated Nitre; and the Marine Acid a regenerated Sea-salt. 3. Mr. Geoffroy demonstrated the reguline part of Antimony to be an ingredient in the Kermes; having procured therefrom an actual Regulus of Antimony, by fusing it with the black flux.

In preparing the Kermes it is necessary to renew the liquor from time to time, as above directed; because, when it is once impregnated with Kermes to a certain degree, it can take up no more; and consequently the same liquor cannot operate again on the Antimony. Experience hath shewn, that, if the doses above prescribed be applied, the liquor will after two hours boiling be sufficiently saturated with Kermes.

If the liquor in which the Kermes is dissolved be filtered while it is very hot, and almost boiling, it leaves nothing on the filter; the Kermes passing through with it: but as it cools it grows turbid, and gradually deposites the Kermes. Therefore it ought not to be filtered till it be cold; or, if it be filtered while it is boiling hot, in order to separate from it some coarse particles of Antimony not yet converted into Kermes, it must be filtered a second time when it is cold, in order to get the Kermes.

Though in the method usually practised for making Kermes, the Antimony is boiled only thrice, yet it does not follow that more Kermes may not be obtained from it, or that but little more would be obtained by a fourth and fifth boiling; on the contrary, it would yield considerably more. Mr. Geoffroy observed, that he got more Kermes by the second boiling than by the first, and still more by the third than by the second; and that the yield goes on increasing in this manner to a very great number of times, which he hath not determined. This increased effect arises from hence, that by multiplying the frictions of the little bits of Antimony against each other, new surfaces are exposed to the action of the Alkaline liquor, and furnish it with more Sulphur; while the addition of this sulphur renders the hepar more active and more penetrating; or, if you please, produces a new hepar every time the matters are boiled. When the Alkaline liquor is once saturated with Kermes, it ceases to act, and forms no new hepar; but it does not follow that its virtue is quite exhausted. To restore its ability of acting as well as at first, or nearly so, you need only let it cool, and deposite the Kermes dissolved in it. We owe this singular observation also to Mr. Geoffroy: he had the patience to go through no less than threescore and ten boilings with the same liquor, without adding any thing but rain water, to supply the place of what was dissipated by evaporation: and he always obtained a pretty considerable quantity of Kermes by each boiling, for the reason given above.

Boiling is not the only means of making Kermes. Mr. Geoffroy found the way of making it by fusion. For this purpose you must mix accurately one part of very pure Fixed Alkali, dried and pulverized, with two parts of Hungarian Antimony also pulverized, and melt the mixture. Mr. Geoffroy made use of a retort. When the mass is melted, it must again be pulverized, while it is still hot, and then put into, and kept in, boiling hot water for an hour or two; after which the liquor, now become saline and antimonial, must be filtered into another vessel filled with boiling water. Every ounce of Antimony treated in this manner yields, by thrice boiling the melted mass, from six drams to six drams and a half of Kermes; which differs from the Kermes made by boiling, only in that it is not quite so soft to the touch, having in every other respect the same qualities.

As Liver of Sulphur is made two different ways, to wit, by boiling and by fusion, and as the Kermes is nothing but a Liver of Sulphur in which the reguline part is dissolved; it follows that Kermes may be made by fusion as well as by boiling. It is necessary to pulverize the melted mass, and to steep it in boiling hot water for an hour or two, that the water may dissolve and divide it sufficiently to make the Kermes fine and beautiful.

With the same view, that is, to make it finer and more perfect, Mr. Geoffroy orders the water saturated with the Kermes made by fusion, to be received, when filtered, in a vessel full of other boiling hot water. He observed, that when the liquor impregnated with Kermes cools too fast, the Kermes that precipitates is much coarser. The warm solution of Kermes is diffused through the boiling-hot water into which it is filtered, and is thereby enabled to retain its heat so much the longer.

From what hath been said on the nature of Kermes, it plainly appears that there must be a great resemblance between it and the Golden Sulphur of Antimony, obtained from the scoria, either of plain Regulus of Antimony, or of the Liver of Antimony; this Golden Sulphur being no other than a portion of the Antimony combined with the Nitre alkalizated during the operation.

Yet there is a difference in the manner of precipitating these two compounds: for the Kermes precipitates spontaneously, on the bare cooling of the water in which it is dissolved; whereas an Acid is employed to precipitate the Golden Sulphur suspended in the water, with which the scoria of the plain Regulus of Antimony, or that of Liver of Antimony, hath been washed. This gives some ground to suspect that the reguline part is not so intimately united with the Liver of Sulphur in the Kermes, as in the scoriæ from which the Golden Sulphur is obtained.

PROCESS X.

The Vitriolic Acid, whether concentrated or much weakened with water, does not act when cold either on Antimony or on its Regulus. This Acid only dims the splendour of the facets of the Regulus; but if one part of exceeding pure Regulus of Antimony be put into a retort, and four parts of clear concentrated Oil of Vitriol poured on it, as soon as the Acid is heated it turns brown, and emits a most suffocating smell of Sulphur, which increases as the Regulus is penetrated and corroded by the Acid.

On raising the fire, there separates from it a matter that seems mucilaginous; and when the Acid hath boiled some time, the Regulus is converted into a white saline mass, as Mercury is in the preparation of Turbith mineral. At the same time a little Sulphur sublimes into the neck of the retort. At last all the Oil of Vitriol passes over into the receiver, and leaves the Regulus in a white, spungy, saline mass in the retort. When the fire is out, the vessels unluted, and the receiver separated from the retort, there rises a white vapour like that of the smoking liquor of Libavius.

The saline mass left in the retort, after the operation, is found increased to near double its weight: this increased weight is owing to the Acid that hath united with the Regulus.

This combination of the Vitriolic Acid with the Regulus of Antimony is excessively caustic, and cannot, for that reason, be administered internally.

The purest Spirit of Salt hath no sensible effect either on Antimony or its Regulus: but if Antimony be coarsely pounded, it separates therefrom, though slowly, some light, sulphureous flakes.

The action of Spirit of Nitre on this metallic substance is more perceptible: by little and little it attacks the plates of the Antimony, which discharge a great number of air-bubbles. As the dissolution advances, the Acid acquires a greenish colour inclining to blue; and if there be not too much of it, it will be almost entirely imbibed by the Antimony, penetrate between its laminæ, and exfoliate them in the direction of the needles that compose them. If there be too much of the Acid, that is, if it rise above the Antimony, it will destroy these plates, and reduce them to a white powder.

But when the Acid is imbibed slowly, we discover between the swelled laminæ little saline transparent crystals, that vegetate much in the same manner as those of the pyrites, in which small crystals of Vitriol are frequently observed, whose figures are not very well determined. These little crystals between the Antimonial plates are intermixed with yellow particles, which being carefully separated burn like common Sulphur.

All these useful observations, concerning the action of the Acids on Antimony and its Regulus, we owe likewise to Mr. Geoffroy; who advises the collecting a quantity of these little crystals in time; because they disappear soon after they are formed, being probably covered by the white powder, or magistery, which is continually produced as fast as the Nitrous Acid disunites and separates the needle-like fibres of the Antimony.

Mr. Geoffroy observed the same sort of crystals on the Regulus of Antimony, when substituted for crude Antimony in this experiment; but it requires a great deal of care to separate these crystals; for as soon as the air comes into contact with them they lose their transparency; and if you wait till the Regulus be in some measure converted into a magistery, they are not then to be distinguished.

In order therefore to have a good view of these crystals, the Regulus must be broken to pieces; these pieces put in a glass bason, and Spirit of Nitre poured on them to half their heighth, but not to cover them. This Acid penetrates them, exfoliates them in white scales; and on the surface of these scales the crystals shoot of a dead white colour. In two or three days time these crystals vegetate and grow in the form of cauli-flowers: they must then be gathered, to prevent their being confounded in the white magistery which continues to be produced, and would not suffer them to be distinguished. If you attempt to dissolve the reguline part of Antimony by an aqua regis compounded in different proportions, and applied in a different dose from what is prescribed in the process, the Regulus of Antimony will only be calcined, as it is by the other Acids, and will precipitate in the form of a white magistery as fast as it dissolves, so that no part thereof will remain united with the solvent. The proof of this is, that if an alkaline liquor be poured, even to the point of saturation, upon the aqua regis that hath thus dropt the Antimony, no new precipitate will be deposited.

PROCESS XI.

Soon after mixing the Regulus with the Corrosive Sublimate, the matter sometimes grows considerably hot: this is occasioned by the Marine Acid's beginning to act on the reguline part, and to desert its Mercury.

The Butter of Antimony rises with a very moderate heat; because the Acid of Sea salt hath the property of volatilizing, and carrying up along with it, the metallic substances with which it is combined: and for this reason a very gentle heat only is required at the beginning of the operation.

It is absolutely necessary that the neck of the retort be wide and short: for otherwise if the Butter of Antimony should fix and be accumulated therein, it might stop up the passage entirely, and occasion the bursting of the vessels. By this operation we obtain eight parts and three quarters of fine Butter of Antimony, and ten parts of running Mercury; there being left in the retort one part and a half of a rarefied matter, black, white, and red. This is probably the most earthy and most impure part of the Regulus of Antimony.

It is of the utmost consequence to the operator that he avoid with the greatest care the vapours that issue from the vessels, because they are extremely noxious, and may occasion mortal disorders. The Butter of Antimony is a most violent Corrosive and Caustic.

When all the Butter is risen, the receiver is shifted in order to receive the Mercury; which, being disengaged from the Acid that gave it a saline form, appears in its natural form of Quick-silver: but it requires a much greater degree of heat than the Butter of Antimony to raise it by distillation.

If crude Antimony, instead of Regulus of Antimony, be mixed with Corrosive Sublimate, a Butter of Antimony will be obtained in the same manner; but, instead of having a running Mercury after the Butter, you will find a Cinabar sublimed into the neck and upper concavity of the retort.

The reason of this difference is easily conceived: for when the Regulus is used, the Mercury being deserted by its Acid finds no other substance to unite with, and so rises in the form of Quick-silver; but when crude Antimony is employed instead of its Regulus, as the reguline part thereof cannot combine with the Acid without quitting its Sulphur, so this Sulphur, being at liberty, unites with the Mercury, which is so likewise, and therewith forms a Cinabar; which from its origin is named Cinabar of Antimony. When you intend to make both Butter and Cinabar of Antimony at the same time, six parts of Antimony must be mixed with eight of Corrosive Sublimate; and care must be taken, while the Butter is coming over, to warm the neck of the retort by holding some live coals near it, with the precautions necessary to avoid breaking it. This warmth makes the Butter melt and run into the receiver; whereas, being thicker and of a much denser consistence than that made with the Regulus, it would otherwise gather in the neck of the retort, choak it entirely, and burst the vessel.

When the Butter is drawn from crude Antimony, more circumspection is necessary to make it of a beautiful white colour, than when it is obtained from the Regulus: for, if the fire be too strong during the distillation, or if the receiver be not soon enough separated from the neck of the retort, certain red sulphureous vapours, the fore-runners of the Cinabar, will at last ascend, and mixing with the Butter give it a brown colour.

In order to restore its beauty it must be put into a clean retort, and rectified by distilling it over again with a gentle sand-heat. By this rectification the Butter of Antimony becomes more fluid; and by re-distilling it a second time you may give it the thinness and fluidity of an oil.

After the operation there will be found in the receiver three parts and three quarters of Butter of Antimony, and some small crystals adhering to its inside, in the form of sprigs. When you break the retort there exhales from it a sulphureous odour; and you will find in it seven parts of Cinabar of Antimony, the greatest part of which is usually in compact glebes, that are heavy, smooth, shining, blackish throughout most of the mass, but in some places red: another part thereof appears in shining needles, and the rest in powder.

When all the Butter of Antimony is come over, and you begin to see the red vapours that predict the approaching ascent of the Cinabar, the receiver containing the Butter must be removed, lest the colour of the Butter should be spoiled by those sulphureous vapours. Another receiver is usually fitted on, without luting; in which a small quantity of running Mercury is sometimes found, when the operation is finished.

There remains, at the bottom of the retort, a fixed, shining, crystalline, black mass, which may be reduced to a Regulus by the common method.

Butter of Antimony may also be obtained from a mixture of Antimony with any of the other preparations of Mercury in which the Acid of Sea-salt is an ingredient; such as sweet Sublimate, the Mercurial Panacea, and White Precipitate: but as none of these combinations contain so great a proportion of that Acid as is in the Corrosive Sublimate, the Butter obtained by their means is far from being so caustic and so fiery as that which rises from a mixture of Antimony, or its Regulus, with Corrosive Sublimate.

Silver precipitated by the Acid of Sea-salt, and ready to be melted into a Luna cornea, being mixed with powdered Regulus of Antimony yields likewise a Butter of Antimony.

If you propose to make it by this means, you must mingle one part of the Regulus of Antimony in powder with two parts of the Precipitate; put this mixture into a glass retort of such a size that it may fill but one half thereof; set it in a furnace; apply a receiver; begin with a gentle heat, which will make a clear liquor come over; and then increase your fire by degrees. White vapours will rise and condense into a liquid Butter; and in the mean time there will be a slight ebullition in the receiver, attended with a little heat. Continue the fire till nothing more will come over; then let your vessels cool and unlute them.

You will find in the receiver an Oil or Butter of Antimony, partly fluid and partly congealed, somewhat inclined to yellow, weighing an eighth part more than the Regulus of Antimony made use of.

The inside of the retort will be carpeted over with small white flowers, of a brilliant silver colour, and an acid taste; and in the bottom of the retort will be found a hard, compact, ponderous mass, difficult to break, yet falling of itself to a powder; its colour externally grey, white, and blueish; internally black, and shining much like Regulus of Antimony; having a saltish taste on its surface, and weighing about a sixteenth less than the Precipitate of Silver employed in the operation.

This experiment demonstrates that the Acid of Sea-salt hath a greater affinity with Regulus of Antimony than with Silver.

The Butter of Antimony prepared by this method is somewhat less caustic than that made with Corrosive Sublimate. It is called the Lunar Butter of Antimony.

The effervescence that arises in the receiver is remarkable. Probably the Acid of Sea-salt, though reduced into vapours when it ascends out of the retort, is not yet perfectly combined with the reguline part of the Antimony, which it nevertheless carries over with it, and the union is completed in the receiver; which occasions the effervescence observed.

The little white silvery flowers, adhering to the inside of the retort, are flowers of Regulus of Antimony, which sublime towards the end of the distillation.

The compact mass, found at the bottom of the retort, is no other than the Silver separated from its Acid, and combined with a portion of the Regulus of Antimony. The colours and the saltish taste of its surface are occasioned by a remainder of the Marine Acid. This Silver is rendered brittle and eager by the union it hath contracted with some of the Regulus of Antimony.

It is easy to purify it, and restore its ductility, by separating it from the Regulus of Antimony. There are several ways of doing this: one of the most expeditious is to flux it with Nitre, which burns and converts to a calx the semi-metal with which the Silver is adulterated.

PROCESS XII.

In the preceding processes we observed that the Marine Acid will not dissolve the reguline part of Antimony, unless it be very highly concentrated, and more so than it can possibly be while in the form of a liquor. Of this the experiment before us is a further proof. Whilst the Marine Acid is so perfectly dephlegmated, as it is in Corrosive Sublimate and Butter of Antimony, it remains combined with the reguline part of Antimony; but if this combination be dissolved in water, the moment the Acid is weakened by the interposition of the particles of water, it becomes incapable of continuing united with the semi-metal which it had before dissolved; deserts it, and lets it fall in the form of a white powder.

The Pulvis Algaroth is therefore no other than the reguline part of Antimony, attenuated and divided by the union it had contracted with the Acid of Sea-salt, and afterwards separated from that Acid by the intervention of water alone. The proof is, that this powder retains none of the properties of the Butter of Antimony: it is neither so fusible nor so volatile; on the contrary, it is capable of sustaining a very strong degree of fire, without subliming and without melting: it may be reduced to a Regulus: it hath not now the same caustic nature: it is only an emetic; which however is extremely violent, and on that account is never prescribed by any prudent physician.

Another proof, that the Marine Acid is separated from the Regulus of Antimony in the precipitation of the Pulvis Algaroth, is, that the water in which this precipitation is made becomes acid, or a sort of weak Spirit of Salt. If it be evaporated, and concentrated by distillation, a very strong acid liquor may be obtained from it. This Acid goes, very improperly, by the name of the Philosophic Spirit of Vitriol; for it is rather a Spirit of Salt.

The Pulvis Algaroth, made with Butter of Antimony procured from the Regulus, is whiter than that made with Butter of Antimony procured from crude Antimony; probably because the latter always retains some sulphureous particles.

Butter of Antimony exposed to the air attracts the moisture thereof, and partly runs into a liquor; but, as fast as this liquor is produced, it deposites a white sediment, which is an actual Pulvis Algaroth. This also is very agreeable to what we advanced touching the decomposition of Butter of Antimony by the addition of water. The Butter attracts the moisture of the air, because the Acid it contains is exceedingly concentrated; and this moisture produces the same effect as water purposely added.

PROCESS XIII.

Melt Butter of Antimony over warm ashes, and put it into a phial or matrass. Gradually pour on it good Spirit of Nitre, till the matter be entirely dissolved. This usually requires as much Spirit of Nitre as there is Butter of Antimony. During the dissolution fumes will rise, which must be carefully avoided. Pour your solution, which will be clear and of a reddish colour, into a glass cucurbit, or a pan of stone-ware: set it in a sand-bath, and evaporate to dryness with a moderate heat. There will be left a white mass, weighing a fourth part less than the whole quantity used, both of the Butter and the Spirit of Nitre. Let it cool, and again pour on it as much Spirit of Nitre as you used the first time. Place the vessel again in the sand-bath, and evaporate the moisture as before. You will have a white mass that hath neither gained nor lost in weight. On this pour, for the third time, the same quantity of Spirit of Nitre as you did the first time. Again evaporate the moisture to perfect dryness: then increase your fire, and calcine the matter for half an hour. You will have a dry, friable, light, white matter, of an agreeable acid taste; which will fall into a coarse powder, and must be kept in a phial carefully stopt. This is Bezoar Mineral: it is neither caustic nor emetic, and has only a sudorific virtue. It obtained the name it bears, because, like the animal Bezoar, it was imagined to have the property of resisting poison.

OBSERVATIONS.

It is not surprising that the Nitrous Acid poured on Butter of Antimony should dissolve it, and unite with it: for with the Marine Acid, which makes a part of this combination, it forms an aqua regis, which we know is the true solvent of the reguline part of Antimony. But in this dissolution, and the changes it produces, there are some things very remarkable and worthy of attention. 1. The Nitrous Acid, by uniting with the Butter of Antimony, deprives it of its property of rising with a very gentle heat, and makes it much more fixed: it can now be dried, and suffer all its moisture to be evaporated; which is not to be done with pure Butter of Antimony: for that, being exposed to a certain degree of heat, instead of letting go its moisture and remaining dry, rises wholly, without the least appearance of any separation of parts.

2. The Butter of Antimony, which, before its combination with the Nitrous Acid, is a most violent Caustic and Corrosive, becomes so mild after it, that it may not only be taken internally without danger, but hath scarce any sensible operation.

The following considerations will lead us to a reasonable explanation of these phenomena. 1. The Nitrous Acid, when combined with metallic substances, doth not communicate to them the same volatility as they acquire from the Marine Acid. Hence it follows, that, if the Nitrous Acid be added to any combination of a metallic substance with the Marine Acid, this new compound will be rendered less volatile, and consequently more able, without rising in vapours, to bear a degree of heat sufficient to carry off part of its Acid. This is the case with Butter of Antimony, after Spirit of Nitre is mixed with it; especially considering, 2. That the Nitrous Acid cannot unite with the reguline part of the Butter of Antimony without weakening the connection between it and the Marine Acid; whence it follows, that the combination of the Nitrous Acid further facilitates the separation of the Marine Acid from the Regulus. Now as soon as the Marine Acid quits the reguline part, that part becomes more fixed, and consequently more capable of enduring the degree of heat requisite to discharge all the adhering Acid; and not only the Marine, but even the Nitrous also. It is not therefore surprizing that, after the Antimony which remains combined with the Nitrous Acid is dried, it should not possess that corrosive power which it derives only from the Acids wherewith it is armed. In order to free it more perfectly from all Acid, we order the fire to be increased after the third desiccation; and the remainder of the Butter of Antimony to be calcined for a full half-hour longer.

That the Marine Acid is separated from the reguline part of the Butter of Antimony, by the desiccations it undergoes in converting it into Bezoar, is proved by this, that, when these desiccations are performed in close vessels, the liquor drawn off is a true aqua regis, known by the name of the Bezoartic Spirit of Nitre.

It remains to be considered why the Bezoar mineral, though freed from all acid, is not emetic; while the Pulvis Algaroth, which is likewise the reguline part of the Butter of Antimony deprived of its Acid, is such a violent emetic, and even to be dreaded for its remaining causticity.

In order to discover the reason of this difference, it is proper to observe that, when we say Bezoar mineral and the Pulvis Algaroth contain no Acid, we must not be understood in too strict a sense: on the contrary, there is reason to think that a certain quantity of Acid still remains in each of them; which however is scarce worth notice, in comparison of the quantity each contained at first. This being allowed, it will not be hard to find the difference between these two preparations of Antimony. The Pulvis Algaroth is deprived of its Acid by the addition of water alone, which only carries off all the loose Acid it can take up, without making any change in the nature of that which continues in combination with the reguline part. Now, as the Marine Acid is not intimately united with the reguline part in Butter of Antimony; as it still retains some of its properties, such as attracting the moisture of the air, giving manifest tokens of its Acid nature, &c.; and as the corrosive quality of this compound depends on this last in particular; the small portion of Acid left in the Pulvis Algaroth will in some degree preserve its former character: and hence comes the effect of this powder, which still retains a little of the corrosive quality that belonged to the Butter of Antimony.

But this is not the case with the small remainder of Acid, which possibly still continues united with the Bezoar mineral prepared as here directed. This compound hath been exposed to a fire sufficient, not only to dry it, but even to calcine it. Now fire is capable of producing great changes in the texture of bodies. It must have forced off from the Bezoar all the Acid that was not intimately combined with it; and that part which it could not drive off, because of its obstinate adhesion, it must have further united and combined more closely with the metallic earth: for we see that fire greatly promotes the action of solvents on the matters with which they are united.

With regard to the properly emetic quality of the Pulvis Algaroth, it cannot be imputed to the combination of any Acid with that powder; since we see that the most powerfully emetic preparations of Antimony, viz. its Regulus and Glass, contain no Acid: it must therefore be attributed to some cause different from that on which its corrosive quality depends. This cause we shall easily find by attending to the different manners in which the Marine Acid, when alone and in aqua regia, operates on the reguline part of Antimony.

The Marine Acid alone dissolves the Regulus of Antimony, but with great difficulty; nor doth it effect a complete dissolution thereof, as is evident from what hath been already said: whereas the Marine Acid, combined with the Nitrous Acid, and therewith forming an aqua regis, as in the preparation of Bezoar, dissolves the reguline part of Antimony completely and radically. Now, it is certain that, the more efficaciously Acids operate on metallic substances, the more of their phlogiston do they destroy; and we cannot but recollect that the preparations of Antimony are so much the less emetic the less phlogiston they contain, or the further they recede from the nature of a Regulus, and the nearer they approach to that of Diaphoretic Antimony: consequently it is plain how Bezoar mineral, which is a sort of calx of Antimony entirely deprived of its phlogiston by the intimate dissolution thereof made by the Acids of the aqua regis, may be in no degree emetic; while the Pulvis Algaroth, being a true Regulus of Antimony, on which the Marine Acid hath operated but very superficially, and which still contains a great deal of phlogiston, is a most violent emetic.

PROCESS XIV.

Antimony is a volatile mineral, capable of being sublimed into flowers; but this cannot be effected without occasioning a notable change in its parts. The reguline and the sulphureous parts are not united so intimately, or in the same proportion, in the flowers as in the Antimony itself; and accordingly we find these flowers have a strong emetic quality, which Antimony hath not. They are of divers colours; which probably arises from their containing more or less Sulphur. Three or four aludels are placed one over another, not only with a view to provide a greater surface, to which the flowers may adhere, but also to give them room enough to circulate, without which they might burst the vessels.

If you introduce the nosle of a pair of bellows into the pot that contains the Antimony, and blow upon it, the sublimation of the flowers will be much sooner effected. This is a general rule with regard to all matters that are to be sublimed or evaporated; the reason of which we have already given.

It is proper that no interval be left between the furnace and the pot containing the Antimony, lest the heat should be thereby communicated to the aludels, on which the flowers fasten best when they are cold.

After the operation, there remains at the bottom of the pot a portion of Antimony half calcined; which being pulverized, and thoroughly calcined till it emit no fume, may be employed to make the Glass of Antimony.

PROCESS XV.

Put the covers again in their places, and proceed in the same manner as before; when the vessels are cold you will find half as many more flowers as you got the first time.

Proceed thus till you have converted all your Regulus into flowers. This will require a considerable number of sublimations, which, as you advance, will always yield you a greater portion of flowers; respect, however, being had to the quantity of Regulus remaining in the pot.

OBSERVATIONS.

We must here repeat what we said just before, in our observations on the preceding process; viz. that Regulus of Antimony is capable of being wholly elevated and sublimed by the action of fire; but that it must at the same time undergo a considerable change and alteration. These flowers of Regulus of Antimony are very different from every other Antimonial preparation. They resemble the Pearly Matter in this, that they cannot be reduced to a Regulus by any means whatever: but they differ from it, 1. in that they are not fixed; for, when melted by fire, they fly wholly away in vapours: 2. in that they are capable of being dissolved by aqua regis, much in the same manner as the Regulus; whereas the Pearly Matter is known to be indissoluble by any Acid.

As soon as Regulus of Antimony is in fusion, it begins to sublime into flowers; so that it is needless to apply a greater degree of heat than is just sufficient to melt it.

A pan of some width is preferable to a crucible for this operation; because the upper surface of the Regulus melted therein is larger, and, the larger that surface is, the more considerable is the quantity sublimed from it.

The two covers which are applied within and over the pot are designed to check, as much as possible, the dissipation of the melted Regulus; yet without absolutely excluding the free access of the air, the concourse of which is useful in all metallic sublimations. Notwithstanding these precautions, it is impossible to prevent the escape of some of the Regulus, in vapours that cannot be confined. Somewhat less than three fourths of the Regulus made use of is nearly the yield in flowers: the rest evaporates through the interstices left by the covers, which must not be luted for the reason just assigned.

CHAP. II.

Of Bismuth.

PROCESS I.

The ore of Bismuth may also be treated like the ores of Lead and Tin; that is, it may be reduced into a fine powder, mixed with the black flux, a little Borax, and Sea-salt; put into a close crucible, and fused in a melting furnace. In that case you will find a button of Regulus covered with scoria. By this method rather more Bismuth is obtained; and it is best to make use of it when the ore is poor, because, in such a case, none at all would be obtained by the other process. But here care must be taken to apply at once the degree of fire necessary to melt the mixture: for, if it remain long in the fire, much Bismuth will be lost, on account of the great volatility of this semi-metal, and the facility with which it turns to a calx.

Bismuth is pretty frequently found pure in its earthy and stony matrices; and when mineralized it is usually so by Arsenic, which, being still more volatile, flies off in vapours while the ore is melting, provided it be but in a small quantity: if there be much of it, and the ore be smelted by fusing it with the black flux, the Arsenic also is reduced to a Regulus, unites more intimately with the Bismuth, becomes a little more fixed by that union, and increases the quantity of the semi-metallic mass found after the fusion.

Though Bismuth be not usually mineralized by Sulphur, that is not because it is incapable of uniting therewith; for, if equal parts of Bismuth and Sulphur be melted together, after the fusion the Bismuth will be found increased near an eighth part, and formed into a mass disposed in needles much like Antimony.

When we come to treat of the ore of Arsenic, we shall have occasion to say a good deal more concerning Bismuth and its ore; because these minerals resemble each other very much.

Mr. Geoffroy, son of the Academician, hath shewn in a Memoir read before the Academy of Sciences, that there is a great resemblance between Bismuth and Lead. That Memoir, which contains only the beginning of Mr. Geoffroy's course of experiments, proves that the author supports with dignity the glory of his name. It is there demonstrated, by a very great number of experiments, that fire produces the same effects on Bismuth as on Lead. This semi-metal is converted into a calx, into litharge, and into glass, as Lead is; and these productions have the same properties as the preparations of Lead made with the same degree of fire. Bismuth is capable of vitrifying all the imperfect metals, and of carrying them off through the pores of the crucible. So that Gold and Silver may be purified and cupelled by its means, as well as with Lead. You may on this occasion turn to what we have said concerning Lead.

PROCESS II.

Bismuth may also be precipitated by the means of Fixed or Volatile Alkalis; but the precipitate is not of so fine a white as when procured by the means of pure water only.

If a greater quantity of aqua fortis, than that prescribed in the process, be made use of to dissolve the Bismuth, a great deal more water will also be required to precipitate the Magistery; because there will be much more Acid to weaken. This white ought to be well washed, in order to free it from any remainder of acidity; and it should be kept in a bottle well stopped; because the access of the air makes it turn brown, and if any of the Acid be left it will turn it yellow.

A solution of Bismuth prepared with the proper quantity of aqua fortis, that is, with two parts of the Acid to one of the semi-metal, concretes into little crystals almost as soon as made.

Aqua fortis not only acts on Bismuth when separated from its ore, and reduced to a Regulus, but attacks it even in its ore, and likewise dissolves at the same time some portion of the ore itself. With this solution of the ore of Bismuth Mr. Hellot makes a very curious Sympathetic Ink, differing from all that were known before.

Mr. Hellot prepares the liquor in the following manner: "He bruises the ore of Bismuth to a coarse powder. On two ounces of this powder he pours a mixture of five ounces of common water with five ounces of aqua fortis. He does not heat the vessel till the first ebullitions are over. He then sets it in a gentle sand-heat, and lets it digest there till he sees no more air bubbles rise. When none appear in this heat, he increases it so as to make the solvent boil slightly for a full quarter of an hour. It takes up a tincture nearly of the colour of brown beer. The ore that gives the aqua fortis this colour is the best. He then lets the solution cool, laying the matrass on its side, that he may decant the liquor more conveniently when all is precipitated that is not taken up by the solvent.

"The second vessel, into which the liquor is first decanted, he also lays declining, that a new precipitation of the undissolved matters may be obtained; after which he pours the liquor into a third vessel. This liquor must not be filtered, if you would have the rest of the process succeed perfectly; because the aqua fortis would dissolve some of the paper, and that would spoil the colour of your paper.

"When this solution, which Mr. Hellot calls the Impregnation, is thoroughly clarified by being decanted three or four times, he puts it into a glass bason with two ounces of very pure Sea-salt. The fine white salt made by the sun succeeded best with Mr. Hellot. If that cannot be had, common bay-salt, purified by solution, filtration, and crystallization, may be used instead of it. But as it is rare to meet with any of the sort that is not a little tainted with iron, the white bay-salt is to be preferred. The glass bason he sets in a gentle sand-heat, and keeps it there till the mixture be reduced by evaporation to an almost dry saline mass.

"If you desire to save the aqua regis, the impregnation must be put into a retort, and distilled with the gentle heat of a sand-bath. But there is an inconveniency, as Mr. Hellot observes, in employing a retort; which is, that, as the saline mass cannot be stirred while it coagulates in the retort, it is reduced to a compact cake of coloured Salt, which presents but one single surface to the water in which it must be dissolved; so that the dissolution thereof takes up sometimes no less than five or six days. In the bason, on the contrary, the saline mass is easily brought to a granulated Salt, by stirring it with a glass rod; and, when thus granulated, it has a great deal more surface; it dissolves more easily, and yields its tincture to water in four hours time. Indeed one is more exposed to the vapours of the solvent, which would be dangerous, if the operation were to be often performed, without proper precautions.

"When the bason, or little vessel, containing the mixture of the Impregnation and Sea-salt is heated, the liquor, which was of an orange-coloured red, becomes a crimson red; and, when all the phlegm of the solvent is evaporated, it acquires a beautiful emerald colour. By degrees it thickens, and acquires the colour of a mass of Verdegris. It must then be carefully stirred with the glass rod, in order to granulate the Salt, which must not be kept over the fire till it be perfectly dry; because you run a risk of losing irrecoverably the colour you are seeking. You may be sure you have lost it, if by too much heat the Salt that was of a green colour become of a dirty yellow. If it be once brought to this state, it will continue without changing when cold: but if care be taken to remove it from the fire while it is still green, you will see it gradually grow pale, and become of a beautiful rose colour as it cools.

"Mr. Hellot removes it from this vessel, and throws it into another containing distilled rain water: and this second vessel he keeps in gentle digestion till he observes that the powder which falls to the bottom is perfectly white. If, after three or four hours digesting, this powder still continues tinged with a rose colour, it is a proof that water enough was not added to dissolve all the Salt impregnated with the tincture of the solution. In this case, the first tinged liquor must be poured off, and fresh water added, in proportion to the quantity of tinged Salt, that is supposed to remain mixed with the precipitate.

"When the ore is pure, and doth not contain a great deal of fusible stone, commonly called Fluor or Quartz, an ounce of it generally yields tincture enough for eight or nine ounces of water, and the liquor is of a beautiful colour like that of the lilach or pipe-tree blossom. In order to prove the effect of this tincture, you must write with this lilach-coloured liquor on good well-gummed paper, that does not sink: or you may use it to shade the leaves of some tree or plant, having first drawn the outlines thereof lightly, with China-ink or with a black-lead pencil. Let this coloured drawing, or writing, dry in a warm air. You will perceive no colour while it is cold; but if it be gently warmed before the fire, you will see the writing, or the drawing, gradually acquire a blue or greenish-blue colour, which is visible as long as the paper continues a little warm, and disappears entirely when it cools."

The singularity of this sympathetic ink consists in its property of disappearing entirely and becoming invisible, though it be not touched with any thing whatever: and this distinguishes it from all others; which, when once rendered visible by the application of proper means, do not again disappear, or at least not without touching the strokes on the paper with some other liquor.

Mr. Hellot made a vast variety of experiments on this subject, and gave his sympathetic ink successively the properties of all others that are known.

It follows from Mr. Hellot's experiments, that it is the Acid of Sea-salt which makes this saline magma of a green colour while it is hot: that without this Acid the saline matter continues red; and that the solution of Bismuth-ore in aqua fortis may therefore serve as a touchstone, to discover whether or no any unknown Salt under examination contains Sea-salt, or a portion of the Marine Acid.

He also proves, in the Memoirs he hath given in on this subject, that the Nitrous Acid is the true solvent of those ores of Bismuth which contain moreover Smalt and Arsenic. That Acid dissolves all the metallic and colouring matters contained in those ores, sparing nothing but the sulphureous and arsenical portion, the greatest part of which remains precipitated; and from this colouring matter the sympathetic ink derives its virtue.

Under the head of Arsenic we shall speak more amply of this matter in Cobalt, or the ore of Arsenic, that gives a blue colour to the sand with which it is vitrified.

The Vitriolic Acid does not, properly speaking, dissolve Bismuth. If to one part and an half of this semi-metal you add one part of Oil of Vitriol; distil the whole to dryness; and then lixiviate with water what remains in the retort; the liquor you obtained by this means will be of a reddish yellow colour, but will let nothing fall when mixed with an Alkali: and this shews that the Vitriolic Acid acts only upon the inflammable part of Bismuth, and doth not dissolve its metallic earth.

It dissolves the ore of Bismuth more perceptibly than Bismuth itself; because the ore contains, besides the reguline part, an arsenical matter, and a coloured matter, over which perhaps it hath more power.

The Acid of Sea-salt attacks and dissolves Bismuth in some small measure, but slowly and with difficulty. That this Acid dissolves a portion of our semi-metal may be proved, by mixing a Fixed or Volatile Alkali with Spirit of Salt in which Bismuth hath lain some time digesting; for then a precipitate falls.

But, though the Marine Acid be capable of dissolving Bismuth, it doth not follow that it hath a greater affinity than the Nitrous Acid with this metallic substance, as some Chymists have thought; who imagined that, in the precipitation of the Magistery of Bismuth by a solution of Sea-salt, the Acid of that Salt quits its basis to unite with the Bismuth which it precipitates, as is the case in the precipitations of Lead and of Silver by the same Salt, and that it forms, on this occasion, a Bismuthum corneum.

On this subject, Mr. Pott observed, 1. that, when only a small quantity of the solution of Sea-salt is mixed with the solution of Bismuth in the Nitrous Acid, no precipitate is formed: now it is certain that when the smallest quantity whatever of Sea-salt is mixed with the solution either of Lead or of Silver, a precipitate is immediately deposited, in a quantity proportioned to that of the Salt used.

2. Mr. Pott, having examined the precipitate of Bismuth thrown down by a solution of Sea-salt, found it not to have the properties of a metallic substance rendered horny: on the contrary, that precipitate being exposed to a very violent fire appeared refractory, and could not be melted.

CHAP. III.

Of Zinc.

PROCESS I.

Most of the Zinc we have comes from an ore of difficult fusion that is worked at Goslar, and yields, at one and the same time, Lead, Zinc, and another metallic matter called Cadmia Fornacum, which also contains much Zinc, as we shall afterwards see.

The furnace used for smelting this ore is closed on its fore-side with thin plates or tables of stone, not above an inch thick. This stone is greyish, and bears a violent fire.

In this furnace the ore is melted amidst charcoal, by the help of bellows. Each melting takes twelve hours, during which time the Zinc flowing with the Lead is resolved into flowers and vapours, great part of which adheres to the sides of the furnace in the form of a very hard crust of earth. The workmen take care to remove this crust from time to time; for it would otherwise grow so thick at last as to lessen the cavity of the furnace very considerably.

There adheres moreover to the fore-part of the furnace, which is formed, as we said before, of thin plates of stone, a metallic matter, which is the Zinc, and is carefully collected at the end of each melting, by removing from this part all the live coals. A quantity of small coal is laid unlighted at the bottom; and on this small coal, by striking the stone plates gently with a hammer, the Zinc is made to fall out of the other matter, known by the Latin name of Cadmia Fornacum, among which it appears fixed in a radiated form. To this other matter we may properly enough give the name of Furnace-Calamine. The Zinc falls in the form of a melted metal, all on fire, and in a bright flame. It would soon be entirely burnt and reduced to flowers, as we shall see, if it were not extinguished, and easily cooled and fixed, by being hid under the unlighted small-coal placed below on purpose to receive it.

The Zinc adheres to the fore-part of the furnace preferably to any other, because that being the thinnest is therefore the coolest: and, in order further to promote its fixing on this part, they take care to keep the thin stone plates cool during the operation, by throwing water on them.

Hence it appears, that Zinc is not extracted from its ore by fusion and the precipitation of a Regulus, like other metallic substances. This is owing to the great volatility of our semi-metal, which cannot, without subliming, bear the degree of fire necessary to melt its ore. It is at the same time so combustible, that a great part of it rises in flowers which have not the metalline form.

Mr. Marggraff provides against these inconveniences by working the ore of Zinc in close vessels. By this means he prevents the Zinc from taking fire, and being converted into flowers; so that it sublimes in its metalline form. The water in the recipient serves to receive and cool the drops of Zinc that may be forced quite over the helm. As the operation requires a most violent fire, these drops must needs issue exceeding hot, and, without this precaution, break the recipient.

Mr. Marggraff by the same process extracted Zinc out of the Furnace-Calamine procured from ores containing Zinc; from Tutty, which is a sort of furnace-calamine; from the flowers and from the calx of Zinc; and from the precipitate of White Vitriol; all of them matters known to be Zinc, that wanted nothing but the phlogiston to give it a semi-metalline form, and from which nevertheless no body could ever before him procure any Zinc.

Mr. Marggraff observes, that the Zinc obtained by his process bears being flatted under the hammer into pretty thin plates; which the common Zinc will not do. The cause of this probably is, that the Zinc obtained by his method is more intimately combined with the phlogiston, and contains a greater quantity thereof, than that which is procured in the ordinary way.

PROCESS II.

Zinc takes fire very easily as soon as it is affected by a certain degree of heat; which proves, that in the composition of this semi-metal there is very much phlogiston, united but slightly with its metallic earth. The Flowers into which Zinc resolves, during its combustion, are of a perfectly singular nature, and differ greatly from all the other productions obtainable out of metallic substances.

They may be considered as the very calx of Zinc, or its metallic earth robbed of its phlogiston, and sublimed during the combustion of this semi-metal, being probably carried up by the phlogiston in flying off. For these Flowers, when once sublimed, are afterwards exceedingly fixed: they sustain the greatest violence of fire without rising, and are converted by it into a sort of glass.