Chapter LXIII: Part III: Of Operations on Animal Substances (3)

It is very true that vegetable and animal substances, the only ones that produce Soot in burning, contain some portion of Sea-salt: but then this Salt is very fixed, and seems unfit to rise with the Acid, the Oil, and the subtile Earth, of which the Volatile Alkali is formed. Therefore we must suppose either that its elevation is procured by the force of the fire, aided by the volatility of the matters that exhale in burning; or that, being decomposed by the violence of the combustion, its Acid alone rises with the other principles above-mentioned. The latter seems probable enough: for though in the common operations of Chymistry the bare force of fire doth not seem sufficient to decompose Sea salt; yet the example of Sea-plants, which, before burning, contain this Salt in abundance, and whole ashes contain scarce any at all, but are replete with its fixed part, that is, with its Alkaline basis, seems to prove that, when this Salt is intimately mixed with inflammable matters, it may be destroyed by burning; so that its Acid shall desert its basis, and fly off with the Soot.

Before the exact method of procuring Sal Ammoniac was known, it was generally imagined that the manufacturers, mixed Sea-salt, and even Urine, with the Soot; because these two substances contain the principles of which this Salt consists. But, besides that the contrary now certainly appears from the above-mentioned Memoirs, it hath been shewn by Mr. Duhamel, who hath published several Memoirs and experiments concerning the composition and decomposition of Sal Ammoniac, from which we have partly taken what we have already said on this subject, and which will furnish us with some more curious observations; it hath been shewn, I say, in the first of Mr. Duhamel's Memoirs, printed with those of the Academy for 1735, that the addition of Sea-salt to the Soot, from which Sal Ammoniac is to be extracted, contributes nothing to its production, and cannot increase its quantity. That alone, therefore, which was originally contained in the matters that produced the Soot, enters as a principle into the composition of Sal Ammoniac. We observed also, in treating of the analysis of Soot, that Mr. Boerhaave obtained from it a considerable quantity of an Ammonical Salt without any additament.

Sal Ammoniac is sometimes found perfectly formed in the neighbourhood of Volcanoes. This Salt is probably produced from the fuliginosities of vegetable or animal matters consumed by the fire of the Volcano.

Sal Ammoniac is often impure, because it carries up with it, in sublimation, some of the black charred matter which ought to be left at the bottom of the vessel: but it is easily purified. For this purpose you need only dissolve it in water, filter the solution, then evaporate and crystallize; by which means you will have a very white and very pure Sal Ammoniac. You may, if you please, sublime it again in a cucurbit and blind head, with a fire not too brisk. Some of it will rise in the form of a light white powder, called _Flowers of Sal Ammoniac_. These Flowers are no other than true Sal Ammoniac, which hath suffered no decomposition; because the bare action of fire is not capable of separating the Acid and the Volatile Alkali, of which this Neutral Salt consists. When you intend to decompose it, you must use the means to be mentioned hereafter.

Though Sal Ammoniac be only semi-volatile, and requires a considerable heat to sublime it, yet it hath the property of carrying up with it matters that are very fixed and ponderous; such as metallic substances, and some kinds of earths. For medicinal uses we sublime therewith Iron, Lapis Hæmatites, the Copper in blue Vitriol, &c. and then it takes different names, as _Martial Flowers of Sal Ammoniac_, _Ens veneris_, and other such denominations, which it borrows from the matters sublimed with it.

PROCESS III.

_Sal Ammoniac decompounded by Acids._

Into a large tubulated glass retort put a small quantity of Sal Ammoniac in powder: set your retort in a furnace, and lute on a large ballon, as in the distillation of the smoaking Acids of Nitre and Sea-salt. Through the hole in your retort pour a quantity of Oil of Vitriol, or Spirit of Nitre, equal in weight to your Sal Ammoniac. An effervescence will instantly follow. The mixture will swell, and discharge white vapours, which will come over into the receiver. Stop the hole in the retort immediately, and let the first vapours pass over, together with some drops of liquor, which will distil without fire. Then put a few coals into the furnace, and continue the distillation with a very gentle heat; which however must be increased, little by little, till nothing more will come off. When the operation is finished, you will find in the receiver a Spirit of Salt, if you made use of Oil of Vitriol; or an _Aqua regis_, if Spirit of Nitre was employed: and in the retort will be left a saline mass, which will be either a Glauber's Secret Sal Ammoniac, or a Nitrous Sal Ammoniac, according to the nature of the Acid used to decompound the Sal Ammoniac.

_OBSERVATIONS._

Sal Ammoniac, which consists of the Marine Acid united to a Volatile Alkali, is, with respect to the Vitriolic and Nitrous Acids, just the same as Sea-salt is with respect to those Acids; that is, the Vitriolic and Nitrous Acids, having a greater affinity, than the Marine Acid, with Volatile as well as Fixed Alkalis, will decompound the Sal Ammoniac, by expelling the Acid from its basis, and assuming its place, just as they do with regard to Sea-salt. Most therefore of what was said concerning the decomposition of Sea-salt, and the distillation of its Acid, by the two other Acids, must be applied here.

We shall only observe, that, when the Acid of Sal Ammoniac is to be distilled from it by the interposition of the Vitriolic or Nitrous Acid, great care must be taken to put but a very small quantity of this Salt into the retort; especially if the Acids to be added are concentrated: for, as soon as they mix with the Sal Ammoniac, a great effervescence arises, and the mixture swells to such a degree, that, unless the quantity in the retort be very small, it may run over altogether into the receiver. It is also proper to take notice, that this operation admits of but a small degree of heat, for two reasons; first, because the Acid of the Sal Ammoniac, being very easily dislodged by an Acid stronger than itself, rises also very easily; secondly, because the Sal Ammoniac which is to be decompounded, as well as the Ammoniacal Salts which result from its decomposition, are semi-volatile, and will sublime in substance if they be exposed to the smallest excess of heat. Moreover, the Nitrous Sal Ammoniac would be in danger of taking fire and exploding, for a reason frequently mentioned above.

The Nitrous Sal Ammoniac may be decompounded, as well as Sal Ammoniac, by the Vitriolic Acid. But, as the Nitrous Acid contained in the Salt is the strongest of all Acids next to the Vitriolic, no other Acid but this is able to expel it from its basis; in which respect this Salt resembles Nitre.

Instead of employing the Acids of Vitriol and Nitre to decompound Sal Ammoniac, we might make use of Neutral Salts consisting of these Acids combined with metallic or earthy bases: but then, as this decomposition cannot be effected without a greater degree of heat, there is reason to apprehend that some of the Sal Ammoniac would be thereby sublimed, before it could be decompounded.

PROCESS IV.

_Sal Ammoniac decompounded by Fixed Alkalis. Volatile Salt. The Febrifuge of Sylvius._

Into a glass alembic or retort put Sal Ammoniac and Salt of Tartar, pulverized and mixed together in equal quantities. Set your vessel in a proper furnace, and immediately lute on a large receiver. A little volatile Spirit will ascend; and a volatile Alkali, in a concrete form, very white and beautiful, will sublime into the head, and come over into the receiver, in quantity near two thirds or three fourths of the Sal Ammoniac used. Continue the distillation, increasing the fire by degrees, till nothing more will sublime. Then unlute the vessels. Put up your Volatile Salt immediately into a wide-mouthed bottle, and stop it close with a crystal stopple. At the bottom of the retort, or cucurbit, you will find a saline mass, which, being dissolved and crystallized, will form a Salt nearly cubical, having the taste and other properties of Sea-salt. This is the _Sal Febrifugum Sylvii_.

_OBSERVATIONS._

This decomposition of Sal Ammoniac is the reverse of that in the preceding process. In the former operation it was shewn that the Acid of Sal Ammoniac may be separated from its basis, by applying to that basis a stronger Acid: in the present operation, on the contrary, the basis of this Salt is separated from its Acid, by presenting to that Acid a Fixed Alkali, wherewith it hath a greater affinity than with the Volatile Alkali which serves it for a basis.

The action of Fixed Alkalis upon Sal Ammoniac is so vigorous and sudden, that, as soon as these two matters are mixed together, the Volatile urinous Salt rushes out with great activity, even without the help of heat; so that much of it will be lost, if care be not taken to confine the mixture immediately in those vessels by means of which it is to be distilled.

The Volatile Salt obtained by this operation is white, pure, and very active; having been freed from the greatest part of its superfluous fat matter, both by the union it had contracted with the Marine Acid, and by the Fixed Alkali employed to separate it therefrom. This Salt is so quick and volatile, that if, on taking out the receiver, it be left a little too long exposed to the air, before it be put into the bottle in which it is to be kept, a great deal of it will exhale and be lost. For the same reason care should be taken, while the vessels are unluting, that the vapour of this Salt do not strike the organ of smelling, or be drawn into the lungs in respiration; for it affects those organs so powerfully, and makes such a quick impression on them, that the operator would be in danger of suffocation. Yet it is of great service, when cautiously smelled to, for exciting the vibrations of the _Genus Nervosum_, in Apoplexies, Fainting fits, and Hysterical disorders. But it must always be administered with great caution; for it hath a corrosive quality, and is no less caustic than a Fixed Alkali. This is proved by applying it to the bare skin, and keeping it on by means of a pitch-plaster, so that it cannot fly off in vapours: for, as soon as it begins to grow warm, it produces on the skin a smarting sensation, like that of burning, attended with much pain, and in a very short time makes an eschar like a caustic.

The Volatile Spirit, obtained in the decomposition of Sal Ammoniac by a Fixed Alkali, derives its origin from the Phlegm contained in the saline matters that are mixed together on that occasion. The moister those matters are, the more Spirit there will be. This also is very active and penetrating. But as it owes these qualities wholly to the Volatile Salt dissolved in it, the more of this Spirit comes off, the less Salt will there be.

If you desire to have much Volatile Spirit, a quantity of water, proportioned to the quantity of Spirit you want, must be mixed with the Salts. In this case the distillation begins with a humid vapour, which coagulates on the sides of the receiver into a concrete Salt, almost as soon as it comes over. There rises afterwards an aqueous vapour, not so saline or volatile as the former. This liquor dissolves the Salt that was coagulated before; and, if the water added was in sufficient quantity, it will dissolve the Salt entirely; otherwise it will dissolve but a part thereof, and then it is certain that the liquor is a Volatile Spirit as strongly impregnated with Salt as it can be. The reason why the liquor that rises first contains a great deal more Volatile Salt than the other, in so much that it coagulates and becomes solid, is because the Volatile Salt rises in distillation much more easily than water.

In whatever manner the Volatile Spirit or Salt be distilled from Sal Ammoniac, by means of a Fixed Alkali, we always find at the bottom of the retort, or cucurbit, when the operation is finished, a new Neutral Salt compounded of the Acid of the Sal Ammoniac, and of the Alkali used in the distillation. If the Salt of Tartar be used, this new Neutral Salt will be perfectly like that produced by combining this Alkali with the Acid of Sea-salt, to the point of saturation. The figure of the crystals of this Salt, though much like that of the crystals of Sea-salt, is nevertheless a little different. However, this Salt possesses the chief properties of Sea-salt. It bears the name of _Sal Febrifugum Sylvii_, because that Physician attributed to it the virtue of curing intermitting fevers. But its title to this virtue is very doubtful, at least in this country.

If the Salt of Soda be used, instead of Salt of Tartar, to decompound Sal Ammoniac, a Volatile Spirit and Salt will in like manner be obtained; and the Neutral Salt left in the retort, after distillation, will be a true regenerated Sea-salt, perfectly like native Sea-salt; because, as we have said before, the Salt of Soda is of the same kind with the natural basis of Sea-salt; and the inconsiderable differences, observable between the _Sal Febrifugum_ and Sea-salt, can be attributed only to such as may be found between the Alkaline bases of those two Salts.

PROCESS V.

_Sal Ammoniac decompounded by Absorbent Earths and Lime. The Volatile Spirit of Sal Ammoniac. Fixed Sal Ammoniac. Oil of Lime._

Let one part of Sal Ammoniac, and three parts of Lime, slaked in the air, be pulverized separately, and expeditiously mixed together. Put this mixture immediately into a glass retort, so large that half of it may remain empty. Apply thereto a capacious receiver, with a small hole in it to give vent to the vapours, if needful. Let your retort stand in the furnace about a quarter of an hour, without any fire under it. While it stands thus, a great quantity of invisible vapours will rise, condense into drops, and form a liquor in the receiver. Then put two or three live coals in your furnace, and gradually increase the fire till no more liquor will rise. Now unlute your vessels, taking all possible care to avoid the vapours, and quickly pour the liquor out of the receiver into a bottle, which you must stop with a crystal stopple rubbed with emery. There will remain, at the bottom of the retort, a white mass, consisting of the Lime employed in the distillation, together with the Acid of the Sal Ammoniac: this is called _Fixed Sal Ammoniac_.

_OBSERVATIONS._

In our Elements of the Theory, we explained how we imagine that Lime and other substances, which, according to the Table, have less affinity than Volatile Alkalis with Acids, are nevertheless capable of decompounding Sal Ammoniac, by uniting with its Acid, after expelling it from its basis, which is a Volatile Alkali. To recapitulate our opinion in two words: we conceive this to depend on the fixedness of these earthy and metallic additaments, which enables them to resist the force of fire, and on the volatility of the basis of Sal Ammoniac, which proves a great disadvantage to it when it comes to struggle, as it were, with those fixed additaments, aided by a considerable degree of heat. We shall only observe, that we are not singular in this opinion, nor indeed did we deliver it as a new one; that several modern Chymists concur with us therein, and particularly Mr. Baron, whom we have already mentioned more than once on the subject of Borax; and who, we think, was the first that ever took particular notice of it in print, viz. in his Memoirs on Borax, communicated to the Academy before the publication of our Elements. For the explanation of this phenomenon, therefore, we refer to those Memoirs, which are actually published, and to what we have already said on the subject in our treatise above-mentioned.

Another phenomenon, which is equally singular and curious, furnishes us with matter for several reflections, and gives us occasion to relate, in few words, the result of Mr. Duhamel's most sagacious experiments and speculations tending to discover the cause thereof. The point under consideration is the different forms and properties which the Volatile Alkali assumes, when separated from Sal Ammoniac by the means of a Fixed Alkali, and by the means of Lime. We know that the former is always in a concrete form, unless the mixture, from which it is distilled, be absolutely drenched with water; and that the latter, on the contrary, is always in a fluid form, and constantly liquid, whatever method be taken to distil it.

Some Chymists imagine, that the Volatile Salt of Sal Ammoniac appears in a concrete form, only because it still contains some Acid; whence they conclude that the reason why no concrete Volatile Salt can be obtained by the means of Lime is, because it absorbs all the Acid of the Sal Ammoniac; which is not the case, they say, with Fixed Alkalis. Others impute the constant fluidity of the Volatile Spirit of Sal Ammoniac, obtained with Lime, to the particles of fire which they suppose communicated thereto by that substance. Mr. Duhamel equally refutes both these opinions, by proving from experiments that Fixed Alkalis are capable of absorbing as much Acid as Lime can, and even more; and that, having been calcined as long, and with as violent a fire, as Lime, they must contain and communicate as many particles of fire; if indeed it be possible that the particles of fire should actually be lodged, and continue imprisoned, in calcined substances, as these gentlemen suppose. Yet this is contrary to experience; seeing the Volatile Salt distilled by the means of a Fixed Alkali, though ever so long and ever so violently calcined, is always in a concrete form, and doth not resemble the Volatile Spirit of Sal Ammoniac prepared with Lime.

In order to throw the necessary lights on this point, Mr. Duhamel had recourse to the only method that can be depended on in Natural Philosophy; namely, Experiments. He accordingly made several, of which these are the chief.

First, he distilled a Volatile Salt, by the means of well desiccated Salt of Tartar, and Salt of Soda; and, urging the fire with great violence towards the end of the operation, he thus obtained a quantity of Volatile Salt equal to, or even exceeding, that of the Sal Ammoniac he used: whence he justly concluded that, on this occasion, the Volatile Salt carried up, and volatilized some of the Fixed Salt.

Secondly, he found upon trial that the Volatile Spirit, obtained from Sal Ammoniac by the means of Lime, appears in the form of a liquor, only because it is mixed with some water which was contained in the Lime. Of this truth he had the following decisive proof: having attempted to prepare a Volatile Spirit of Sal Ammoniac with Lime, which had not been slaked, either in the air or by water, he could not obtain any Volatile Spirit: or, at least, the quantity was so small that it might be reckoned as nothing; and even that was wholly due to the moisture which Sal Ammoniac necessarily contains, together with that which Lime imbibes from the air, if ever so little exposed thereto.

From these two experiments Mr. Duhamel draws the following consequences: viz. that the Volatile Salt cannot be separated from the Sal Ammoniac and sublimed, without carrying along with it some of the additament which serves to extricate it; or, instead thereof, some other body with which it is capable of uniting: that Fixed Alkalis have the property of being thus carried up by the Volatile Alkali, and subliming with it: that the case is not the same with Lime, which therefore cannot, when alone, separate and sublime the Volatile Alkali of the Sal Ammoniac; but becomes capable thereof when it hath imbibed any moisture, which joins with the Volatile Salt, and rises therewith in distillation. And hence it must be concluded, that, seeing the Volatile Salt carries up with it some of the Fixed Alkali, by the means of which it is separated, it will be in a concrete form; what it carries up along with it being dry and solid: whereas, when it is distilled with Lime, it cannot but be liquid; seeing it must needs be dissolved by the moisture it gets from the Lime, without which it would not rise.

But to what must we attribute these effects produced by Lime, so different from those produced by Fixed Alkalis? Are they owing to its quality of Lime? or would it produce the same, if it were only a mere Absorbent Earth? Mr. Duhamel hath answered this question by a third sort of experiment. He tried to decompound Sal Ammoniac, and to separate its Volatile Alkali, by a pure Absorbent of Earth, without mixing any water with it, or calcining it.

For this purpose he made use of Chalk; and his experiment succeeded. By means of this additament he decompounded Sal Ammoniac, and by the experiment obtained the lights he wanted. The Volatile Alkali, being extricated by the dry but uncalcined Chalk, rose in a concrete form, as with Fixed Alkalis; and in like manner carried up with it some of the earthy additament. The same Chalk when calcined, and converted into Lime, produced the very effect of Lime on Sal Ammoniac. It is therefore from calcination alone that Absorbent Earths derive the property of retaining obstinately the Volatile Alkali, and preventing its sublimation by refusing to rise with it as Fixed Alkalis do.

Though these ingenious experiments evidently furnish us with great lights, for discovering the cause of the solidity or fluidity of the Volatile Alkali, when separated from Sal Ammoniac by different additaments, as they fully determine several preliminary questions immediately relating thereto; yet they still leave us, in some measure, at a loss with regard to the chief point. For we do not yet know why Fixed Alkalis and Absorbent Earths, which, in all Chymical trials, shew that they have certainly as much fixity as Lime, are carried up by the Volatile Alkali, while Lime resists, instead of rising with it as those other substances do, obstinately retains it, and even fixes it in some measure, so that it is impossible for it to sublime. This question, in my opinion, depends on the theory of Lime; nor can we hope to resolve it in its full extent, till we get a further insight into the nature of that singular substance than we have at present.

On this subject, however, Mr. Duhamel hath offered some conjectures, founded on the known properties of Lime, and supported by experiments. "Lime," says he, "is an earth freed by calcination from almost all its humidity, almost all its Acid, and all the fat it contained; whether that fat came from some animal parts, as is the case of those stones which consist of shells; or whether it were a bituminous fat, as may happen to be the case with some others: this substance is withal acrid and fiery; it is very greedy of moisture, and imbibes it when exposed thereto. It absorbs Acids, and retains them strongly; and, lastly, it unites with fat matters, and therewith makes a kind of soap."

All these properties are verified by experiments; and therefore Mr. Duhamel thinks he hath a right to say, that Lime acts not only on the Acid of Sal Ammoniac, but also on the fatty matter which always accompanies Volatile Alkalis, and is essential to their nature; and therefore it decompounds them. Of this Mr. Duhamel gives the following convincing proof, founded on experiment. He took some Volatile Spirit distilled with Lime, and abstracted it several times from a fresh parcel of Quick-Lime. The quantity of the Spirit diminished sensibly every time; and the Lime was at last so replete with fat, that the Vitriolic Acid, when poured thereon, became very sulphureous; and moreover, when calcined in a crucible, it emitted a very perceptible smell of burnt grease.

Indeed Fixed Alkalis are also capable of absorbing and retaining fat matters; but not near so strongly as Lime: because these Salts are never entirely freed from that which they contain originally; whereas Lime seems much poorer, and absolutely void of any oily matter.

On these principles Mr. Duhamel resolved to try if he could not obtain a Volatile Alkali in a concrete form, by distilling the Volatile Spirit from Lime, brought nearly to the condition of a Fixed Alkali, by imbibing a portion of fat matter. With this view he distilled a great quantity of Volatile Spirit from a little Lime, and actually obtained a small portion of Volatile Salt; because the great quantity of Volatile Spirit had, in some measure, saturated the Lime with fat matter.

Mr. Duhamel tried also to bring Lime back to the condition of a pure Absorbent Earth, to _decalcine_ it, if I may use the term; in order to try whether he could not by this means make it produce the same effect as Chalk. For this purpose he lixiviated some Lime four months successively, pouring every day fresh water on it, and removing that of the preceding day, together with the crystalline crust which always formed on it; and after leaving this Lime two years in the shade, he applied it to Sal Ammoniac. It produced a moderate quantity of Volatile Salt, which was very transparent, and seemed to be crystallized in cubes. Thus we see Lime rendered very like Chalk. Yet it was pretty acrid on the tongue, and the Volatile Salt, obtained by its means, was more disposed to run into a liquid than that separated by Chalk: which shews that this Lime still retained some part of its former character, and that its transformation was not complete.

To conclude what relates to the Volatile Alkali of Sal Ammoniac, it only remains that we say a word or two of that portion of the earthy or saline additament, which, though fixed in its nature, sublimes nevertheless with the Volatile Alkali, and gives it a concrete form.

Mr. Duhamel, who, in every subject that he handles, omits nothing worthy of attention, made several other experiments, with a view to discover whether or no the Salt of Tartar, and the Chalk, carried up by the Volatile Alkali, be truly volatilized; and whether or no there be such a strict union contracted, between the Urinous Salt and these fixed substances, that the whole results in what is called a _Concrete Volatile Salt_; or if those fixed substances be united but superficially with the Urinous Salt, which only carries them up along with itself in sublimation, as Sal Ammoniac carries up several very fixed metallic matters.

The result of the experiments made by Mr. Duhamel for this purpose is, that the fixed substances carried up by the Volatile Alkali of the Sal Ammoniac are actually volatilized; that they make, as it were, one whole with it; and are so closely combined therewith, that almost all the most efficacious means of separating fixed from volatile matters are unsuccessful with regard thereto. Nothing, for instance, is fitter to separate a volatile substance from a fixed one, than to mix the compound with a great quantity of water, and to distil the whole, with such a degree of heat as shall be exactly sufficient to elevate the volatile part. In this manner Mr. Duhamel treated Volatile Alkalis replete with Fixed Salt, and with Chalk: but though he applied no more than the gentlest degree of heat; nay, exposed his mixture to the air only, fearing lest he should make the heat too strong if he used fire; yet the fixed part, which the Volatile Salt had carried up with it, continued still united therewith; so that the whole passed over in distillation, or was dissipated by evaporation, without leaving any thing fixed at the bottom of the vessel.

He also justly looked on Acids as an effectual means of procuring the separation, or decomposition, he was in quest of. We know that, with the Volatile Alkali, they form Ammoniacal Salts, which, though they are not so light as the Volatile Alkali, sublime nevertheless with a moderate heat; and that, on the contrary, the same Acids with Fixed Alkalis, or Absorbent Earths, form Neutral Salts, which resist the violence of fire. On this principle Mr. Duhamel poured Acids, to the point of saturation, upon Volatile Alkalis containing much Fixed Alkali, or Chalk. But this experiment succeeded no better than the foregoing; for the mixture being put to distil, sublimed wholly in Sal Ammoniac. Indeed a little fixed matter was left at the bottom of the retort; but the quantity thereof was too small to merit notice.

At last, the only way Mr. Duhamel could think of, for separating, from a Concrete Volatile Alkali, the fixed parts which that Salt had rendered Volatile, was to expose it to the air, covered with a piece of gauze only; but in its dry state, without dissolving it in water. The Volatile Urinous Salt was by this means dissipated; having deserted the fixed part, which remained at the bottom of the bason, and, being exposed to the fire, retained its fixed nature. But it took more than a year to effect this separation; nor are we sure that it was complete; for it is not certain that all the fixed part was left behind, and that some of it was not dissipated with the Volatile Urinous Salt.

This volatilization, this kind of metamorphosis of a Fixed Alkali and an Absorbent Earth into a Volatile Alkali, is a very curious phenomenon, and deserves to be considered by the best Chymists.

We shall finish our observations on the decomposition of Sal Ammoniac by Lime, with some reflections on the nature of the _caput mortuum_ that remains after this distillation.

This residuum is only Lime impregnated, but not saturated, with the Acid of Sea-salt. If the distillation be urged at last with a violent fire, the _caput mortuum_ will be found formed into a mass, seeming to have been half-melted. This matter is a kind of Phosphorus, and emits light in the dark, when struck with any hard body. Mr. Homberg was the first who discovered it to have this property. Having calcined, and melted together in a crucible, one part of Sal Ammoniac and two parts of Lime, with a design to fix that Salt, he observed the mass remaining after the fusion to have the property just mentioned.

Lime, thus impregnated with the Acid of Sal Ammoniac, is very improperly called by the name of _Fixed Sal Ammoniac_. This compound attracts the moisture of the air, and even runs wholly into a liquid, if it be impregnated with much Acid. It hath almost all the properties of Fixed Alkalis. This liquid is called _Oil of Lime_, for the same reason that deliquated Salt of Tartar is called _Oil of Tartar_.

PROCESS VI.

_Volatile Alkalis combined with Oily matters. A Volatile Oily Aromatic Salt._

Pulverise and mix together equal parts of Sal Ammoniac and Salt of Tartar: put the mixture into a glass or stone cucurbit: pour on it good Spirit of Wine, till it rise half an inch above the matter. Mix the whole with a wooden spatula; apply a head and a receiver, and distil in a sand-bath, gently heated, for two or three hours. A Volatile Salt will rise into the head; and then the Spirit of Wine will distil into the receiver, carrying with it a portion of the Volatile Salt.

When nothing more will come over, let your vessels cool; then unlute them, separate the Volatile Salt, and weigh it directly. Return it into a glass cucurbit, and for every ounce thereof add a dram and a half of Essential Oil, drawn from one or more sorts of aromatic plants. Stir the whole with a wooden spatula, that the Essence may incorporate thoroughly with the Volatile Salt. Cover the cucurbit with a head, fit on a receiver, and, having luted it exactly, distil in a sand-bath, as before, with a very gentle heat. All the Volatile Salt will rise, and stick to the head. Let the fire go out, and when the vessels are cooled take your Salt out of the head. It will have an odour compounded of its own proper smell, and the smell of the Essence with which it is combined. This is an _Aromatic Oily Salt_. Put it into a bottle stopped close with a crystal stopple.

_OBSERVATIONS._

The design of this operation is to incorporate and unite an Oil with a Volatile Alkali. Spirit of Wine is added in the distillation of the Volatile Salt, intended for this purpose, in order to prepare it for receiving the Oil, and combining more easily therewith. This Salt hath the property, as was shewn in the preceding operation, to carry up with it part of the substances with which it is distilled. On this occasion therefore, it is impregnated with a little of the Spirit of Wine; and this Spirit, which contains in itself an oily matter, and is the solvent of Oils, cannot fail to facilitate the union of the Oil with the Volatile Salt, as it serves for a medium between them. Yet it must not be considered as a necessary one. A Volatile Salt, sublimed with Salt of Tartar alone, would also very readily take up any Oil with which it should be distilled. We have seen that Volatile Alkalis are originally impregnated with much Oil, which is radically dissolved in them; and consequently they have a great affinity with that substance. So that if we distil them with Spirit of Wine, at the beginning of this operation, we do it not out of any necessity, but only with a view to accelerate or facilitate the intended union.

In this distillation the Volatile Alkali always rises first, and before the Spirit of Wine; which proves that it is much more volatile, though it be more ponderous than the Spirit.

If the Spirit of Wine used in this distillation be very aqueous, it will dissolve the Salt as it comes over, and will reduce it into a Spirit: but if, on the contrary, it be well dephlegmated, the Volatile Alkali will remain in a concrete form, and will not be dissolved in this first distillation.

If you desire to have the Volatile Salt entirely dissolved in the Spirit of Wine, though highly dephlegmated, it must be repeatedly distilled a great number of times with the same Spirit of Wine: for, though the small quantity of Spirit of Wine, with which it unites in the first distillation, be not capable of reducing it into a liquid, yet, as it takes up more and more every time it is distilled, it dissolves at last, and then with the Spirit of Wine forms a fluid that appears perfectly homogeneous. The Volatile Alkali is now rendered considerably milder by the union thus contracted, and is accordingly called the _Dulcified Volatile Spirit of Sal Ammoniac_.

When well dephlegmated Spirit of Wine is mixed with a Volatile Spirit of Sal Ammoniac, perfectly saturated with Volatile Salt, these two liquors together immediately form a white opaque _coagulum_. But for this purpose you must not use a Volatile Spirit distilled with Lime; for then the experiment will not succeed.

This _coagulum_ does not seem to be the effect of an intimate union between the two substances mixed together, like that which results from the union of a Fixed Alkali with an Oil. It hath just now been shewn that Spirit of Wine and a Volatile Alkali do not readily unite together. I believe the effect rather depends on this, that Spirit of Wine hath a greater affinity than the Volatile Salt with water; and therefore the Spirit, which ought to be perfectly dephlegmated, attracts the water wherein the Volatile Salt was dissolved, which thereupon recovers its concrete form; and being at that time mixed with the Spirit of Wine, it keeps that Spirit locked up among its parts, and hinders it from appearing with its natural fluidity.

What confirms this notion is, that the _coagulum_, which at first seems to make but one whole, soon separates into two parts, whereof one, which is solid, and nothing but the Volatile Salt concreted, lies at the bottom of the vessel; and the other, which is fluid, cannot be mistaken for any thing but the Spirit of Wine, which, being disengaged from the particles of Salt, recovers the form of a liquid, and, being the lightest, floats over the Salt. Yet these two substances, though now very distinct from each other, are not so pure as before they were mixed together. The Spirit of Wine hath dissolved a little of the Volatile Salt; and, on the other hand, the Volatile Salt retains a little of the Spirit of Wine. They may indeed be perfectly united and blended with each other, by the method above delivered; that is, by being frequently distilled and cohobated together, till they form one mixt; but then that mixt will be in a liquid form.

The first time this mixture is distilled, a great deal of Volatile Salt rises first, which is very fit to unite with an Essential Oil, and so to become a Volatile Oily Aromatic Salt.

THE END.

_GEOFFROY'S TABLE of the COMPARATIVE AFFINITIES observed between sundry substances._]

I. Acid Spirits
Fixed Alkali
Volatile Alkali
Absorbent Earths
Metallic Substances

II. Marine Acid
Tin
Regulus of Antimony
Copper
Silver
Mercury

Gold

III. Nitrous Acid
Iron
Copper
Lead
Mercury
Silver

IV. Vitriolic Acid
Phlogiston
Fixed Alkali
Volatile Alkali
Absorbent Earths
Iron
Copper
Silver

V. Absorbent Earths
Vitriolic Acid
Nitrous Acid
Marine Acid

VI. Fixed Alkali
Vitriolic Acid
Nitrous Acid
Marine Acid
Spirit of Vinegar
Sulphur

VII. Volatile Alkali
Vitriolic Acid
Nitrous Acid
Marine Acid

VIII. Metallic Substances
Marine Acid
Vitriolic Acid
Nitrous Acid

IX. Sulphur
Fixed Alkali
Iron
Copper
Lead
Silver
Regulus of Antimony
Mercury
Gold

X. Mercury
Gold
Silver
Lead
Copper
Zinc
Regulus of Antimony

XI. Lead
Silver
Copper

XII. Copper
Mercury
Calomine

XIII. Silver
Lead
Copper

XIV. Iron
Regulus of Antimony
Silver, Copper, Lead

XV. Regulus of Antimony
Iron
Silver, Copper, Lead

XVI. Water
Ardent Spirits
Neutral Salts

EXPLANATION OF THE PLATES.

PLATE FIRST.

FIG. I. _A Copper Alembic._

A. The Cucurbit or Body.
B. The Neck.
C. The Head.
D. The Beak, Nose, or Spout.
E. The Refrigeratory, or Cooler.
F. Its Cock.
G. The Receiver.

FIG. II. _A Glass Alembic._

A. The Cucurbit.
B. The Head.
C. The Gutter within the Head.
D. The Beak.

FIG. III. _A long-necked Glass Alembic._

A. The Body of the Matrass.
B. The Neck.
C. The Head.

PLATE SECOND.

FIG. I. _A Glass Alembic of one piece._

A. The Cucurbit.
B. The Head.
C. The Aperture in the Head.
D. Its Stopple.
E. The Mouth of the Cucurbit.

FIG. II. _A Pelican._

A. The Cucurbit.
B. The Head.
C. The Aperture in the Head, with its Stopple.
D. D. The two curved Spouts.

FIG. III. _A Row of Aludels._

FIG. IV. _A Retort._

A. Its Bowl.
B. Its Neck.

FIG. V. _An English Retort._

PLATE THIRD.

FIG. I. _A Reverberating Furnace._

A. The Ash-hole Door.
B. The Fire-place Door.
C. C. C. C. Registers.
D. The Dome, or Reverberatory.
E. The Conical Funnel.
F. The Retort in the Furnace.
G. The Receiver.
H. H. Iron Bars to sustain the Retort.

FIG. II. _The Conical Funnel by itself._

FIG. III. _Back View of a Muffle._

A. The bottom of the Muffle.
B. Its Arch.
C. C. C. Lateral apertures.

FIG. IV. _Fore-View of a Muffle._

FIG. V. _A Melting Furnace._

A. A. The Base of the Furnace.
B. The Ash-hole.
C. D. The Grate for the Fire.
E. The Fire-place.
F. G. H. Curvature of the inside of the upper part of the
Fire-place.
I. The Shaft or Chimney.

PLATE FOURTH.

_A Cupelling Furnace._

A. The Ash-hole.
B. B. Its sliding Doors.
C. The Fire-place.
D. D. Its sliding Doors.
E. F. Small apertures in the Sliders.
G. G. Holes for Bars to bear the Muffles.
H. H. H. Iron braces in the fore-part of the Furnace, which form
grooves for the Doors of the Fire-place and Ash-hole to slide in.
I. The upper pyramidal part of the Furnace.
K. An aperture therein for managing the Coals.
L. The opening at top.
M. The Pyramidal Cover.
N. The Chimney or end of the Shaft, on which the conical Funnel
may be fitted.
O. O. O. O. Handles for moving the sliding Doors.
P. P. Ears of the Pyramidal Cover.

_N. B._ The Furnaces, as represented in the two last Plates, are not in due proportion to each other. The Cupelling Furnace is much larger than it should be, with respect to the Melting Furnace. These dimensions are here given it, only that all its parts might be more distinctly expressed, than could have been done if we had made it less.

INDEX.

A

Absorbent Earths, _Pag._ 5, 512

Acetous Fermentation, 90, 536, 539

Acids in general, 13
the Universal, or Vitriolic, 19, 172
the Nitrous, 12, 170
the Marine, 25, 213
the Vegetable, 90, 440
the Animal, 107, 578

Acids dulcified, 87

Adopters, 132

Æther, 88, 492, 501

Æthiops Mineral, 61, 304
of Antimony, 63

Affinities between Bodies in general, 9
of Acids in general, 121
of the Marine Acid, 122
of the Nitrous Acid, 123
of the Vitriolic Acid, _ib._
of Absorbent Earths, _ib._
of Fixed Alkalis, _ib._
of Volatile Alkalis, 124
of Metallic Substances, _ib._
of Sulphur, _ib._
of Mercury, _ib._
of Lead, 125
of Copper, _ib._
of Silver, _ib._
of Iron, _ib._
of Regulus of Antimony, _ib._
of Water, _ib._
of Spirit of Wine, _ib._

Air, 2
from Guaiacum-Wood, 440
from Tartar, 516

Alembics of Metal, 128

Alembics of Glass, 129
tubulated, _ib._

_Algaroth, Pulvis_, 342

Alkalis, 14
Fixed, 14, 106, 448, 449
from Sea-salt, 26
from maritime plants, 106
from burnt vegetables, 448
from Nitre, 187
from Tartar, 515
from Wine-lees, 517
made more Caustic by quick-lime, 36, 455
Volatile, 98, 107, 446, 599, 609
from plants with cruciform flowers, 445

Alkohol, 88, 484

Aludels, 130

Alum, 19, 165
Roman, 167

Amalgams, 59, 233

Amber, 119, 467

Ammoniacal Salts, 98

Analysis, Chymical, 101
of Vegetables, 102
of Animals, 106
of Minerals, 108
of Guaiacum Wood, 440
of Mustard-seed, 445
of Wood-soot, 457
of Turpentine, 460
of Benzoin, 463
of Amber, 467
of Bees-Wax, 472
of Honey, 474
of Gum-Arabic, 476
of Wine, 480
of Spirit of Wine, 486
of Tartar, 514
of Vinegar, 542
of Putrid Vegetables, 559
of Butter, 566
of Cheese, 569
of Whey, 571
of Bullock's Blood, 574
of Beef, 580
of Ox-bones, 583
of Mutton-Suet, 584
of Pullet's Eggs, 586
of Human Excrement, 588
Urine, 596

Animals, 106, 574

Anodyne Mineral Liquor, 500

Antimony, Crude, 65, 116, 234, 315, 335, 339
Diaphoretic, 67, 326
unwashed, 329

_Aqua Fortis_, 24, 42
purified, 43
blue, 377

_Aqua Phagedenica_, 312

_Aqua Regis_, 38, 42, 217, 227

_Aquila Alba_, 61, 312

_Arcanum Duplicatum_, 19
_Corrallinum_, 60, 308

Ardent Spirits, 85, 481

Aromatic strong Waters, 514
Oily Volatile Salt, 620

Arsenic, 72, 118
Fixed, 381

Assay, parting, 42, 250

Ash-hole, 134

_Aurum Fulminans_, 38, 39, 229
reduced, 38, 39, 230

B

Ballons, 132

_Balneum Mariæ_, 133

Balsams, 81, 460
of Sulphur, 434

Bar iron, 48

Basis of Sea-Salt, 26
of Nitre, 185

Baths, Water, Vapour, Sand, 133

Beak of an Alembic, 128

Bee's-wax, 472

Bell-metal, 53

Benjamin, or Benzoin, 463

Bezoar Mineral, 64, 343

Bezoartic Spirit of Nitre, _ib._

Bile, 108

Bismuth, 69, 117, 350

Bitumens, Native, 79, 119, 467
Artificial, 493, 513

Black Copper, 263, 264
Flux, 241

Blind Head, 130

Blood, 108, 574

Blue _Aqua Fortis_, 377
Enamel, 371
Powder, _ib._
Vitriol, 46, 111, 286

Boles, 169

Bones, 583

Borax, 27, 218, 524

Brandy, 85, 483

Brass, 71, 352

Brewing Malt liquor, 479

Bronze, 53

Burnt Alum, 19

Butter of Antimony, 64, 338
Lunar, 341
of Bee's-wax, 472
of Cacao, 410, 473
of Milk, 564, 566, 568

C

_Cadmia Fornacum_, 71, 358

Calamine, or _Lapis Calaminaris_, 71, 118, 357

Calcination, 29, 30, 36, 117

Calx of Antimony, 63, 321
reduced, 323
vitrified, 330
of Arsenic, 367
of Bismuth, 69
of Copper, 267
of Lead, 292

Calx of Tin, 52, 280
of Zinc, 361

Camphor, Native, 465
Factitious, 466

_Caput mortuum_, 105

Carat, 55

Caustic Stone, common Caustic, or potential Cautery, 33, 455

Cementation, 48, 258

_Cendre Gravelée_, 517

Ceruse, 92, 553

Chalybeated Tartar, 95, 528
Soluble, 94, 528

Charcoal, 8, 77, 449

Cheese, 562

Churning, 564

Chyle, 108, 393, 563

Chymical Decomposition, 101
Vessels, 126
Furnaces, 133

Chymistry, its Object, 1

Cinabar, 62, 116, 298, 306
of Antimony, 69, 338

_Clyssus_ of Antimony, 330
of Nitre, 189

Coal, 8, 77, 449

Cobalt, 119, 367

Cohobation, 130

Colcothar, 174
its Salt, _ib._

Colophony, 462

Combination of Mercury with Sulphur, 306
with the Marine Acid, 308
of Regulus of Antimony with the Marine Acid, 338
of Zinc with Copper, 361
of Fat Oils with Acids, 398
with Fixed Alkalis, 400
with Sulphur, 405
with Lead, 406
of Essential Oils with Sulphur, 434
with Fixed Alkalis, 438
of Spirit of Wine with the vitriolic Acid, 492
with Spirit of Nitre, 503
with the Marine Acid, 508
of Crystal of Tartar with Absorbent Earths, 519
of Crystal of Tartar with Fixed Alkalis, 524
with Iron, 528
with Regulus of Antimony, 534
of Vinegar with Alkalis, 547
with Copper, 550
with Lead, 552
of a Volatile Alkali with Acids, 602
with oily Matters, 618

Combustion, its effect on Vegetables, 448

Condensation of Air, 3

Cooler of an Alembic, 129

Copper, 44, 113, 247, 253, 262, 289
separated from Iron, 56
from Lead, _ib._
Black, 263

Copperas, or Green Vitriol, 49, 160

Corrosive Sublimate, 61, 308

Cream, of Milk, 562
of Tartar, 93, 517

_Cremor Calcis_, 30, 520

_Crocus Martis_, 49, 276
_Aperiens_, 51, 277
_Astringens_, _ib._
_Metallorum_, 66, 326

Crucibles, 132

Cruciform flowered Plants, 445

Crystallization, 16

Crystals of Antimony, 336
of Arsenic, 72, 377
of Bismuth, 253
of Silver, 40, 254
of Tartar, 93, 517
of Lead, 92, 297
of Mercury, 307
of Venus, or Copper, 550

Cucurbit, 128

Cupel, 55, 243

Cupelling, 243

Curd, 56, 569

D

Decoction, 410, 419

Decomposition, Chymical, 101
of Sulphur by burning it, 176
of vitriolated Tartar by means of the Phlogiston, 179
of Nitre by means of the Phlogiston, 186
of the vitriolic Acid, 191
of Arsenic, 377
of Sea-salt by means of the Phlogiston, 197
of the vitriolic Acid, 211
of the Nitrous Acid, 217
of Borax by means of Acids, 218
of Butter of Antimony by means of Water, 342
of Fat Oils combined with Acids, 398
with Fixed Alkalis, 400
with Lead, 406
of Essential Oils combined with Sulphur, 434
with Fixed Alkalis, 438
of Spirit of Wine combined with the vitriolic Acid, 492
of Soluble Tartars, 95, 526
of Regenerated Tartar, 547
of Salt of Coral, Crab's eyes, Pearl, &c., 549
of Verdegris, 550
of Salt or Sugar of Lead, 555
of Sal Ammoniac by Acids, 607
by Fixed Alkalis, 608
by Absorbent Earths and Lime, 611

Decrepitation, 27

_Deliquium_, 12

Diaphoretic Antimony, or Mineral, 65, 67, 326
Unwashed, 329
Dissolution of Metals, 35

Distillation, 101
_per descensum_, 127, 419
_per ascensum_, 128
_per latus_, 131

Distilled Verdegris, 550
Vinegar, 91

Dome of a Furnace, 135

Dry way of parting Metals, 42

Drying varnish, 87

Dulcified Acids, _ib._
Volatile Spirit of Sal Ammoniac, 620

E

Earth, 4
fusible or vitrifiable, 5, 29
unfusible or unvitrifiable, _ib._
absorbent, 5
calcinable and uncalcinable, 29

Eggs analyzed, 586

Elasticity of air, 3

Elements of Bodies, 2

Elixirs, 512

Emetic Tartar, 95, 326, 331, 534
Wine, 326, 331

Empyreumatic Oils, 82

Emulsion; vegetable, 104, 392
Animal, 563, 587

Enamel, 52
Blue, 371

_Ens Veneris_, 607

Epsom Salt, 196

Essential Oils, _see_ Oils.

Essential Salts, 103, 387
of Vinegar, 545
of Wine, 103
of Flesh, 582

Expressed Juices, of Plants, 103, 383
of Animals, 106

Expressed Oils, 103, 386, 387

Extracts, 104, 106, 419
by Triture, 389

F

Falsification of Essential Oils, 425

Fat, Animal, 107, 584

Fat Oils by expression, 103, 386
by decoction, 410
attenuated, 395

Fat Lute, 148

Febrifuge of Sylvius, 608

Ferment, or Yest, 481

Fermentation, 83
Vinous or Spirituous, 83, 478, 481
checked, 481
Acetous, 83, 87, 90, 536
Putrefactive, 83, 557

Fetid or empyreumatic Oils, 82

Fire, element of, 5
how applied, 134
naked, _ib._

Fire-place, of a Furnace, _ib._

Fixed Nitre, 23
Sulphur of Antimony, 68, 329
Sal Ammoniac, 618
Arsenic, 381

Flesh analyzed, 580

Flints, 29

Flowers, 130
of Antimony, 63, 347
of Regulus of Antimony, 348
of Sulphur, 20
of Zinc, 70, 359
of Benzoin, 463
of Sal Ammoniac, 606
Martial, 607

Fluor, of an Ore, 110
aqueous of a Salt, 180

Fluxes, 46, 241

Foliated Salt of Tartar, 549

Forge, 142

Forged Iron, 48

Fulguration in cupelling, 244

Fulmination of Nitre, 23

Furnaces their Construction, 134
Reverberating, 137
Melting, 140
Cupelling, 142
Lamp-heat, 146
Forge-heat, 142

Furnace-Calamine, 358

G

Glass, 5
of Lead, 54, 293
of Antimony, 63, 330
of Bismuth, 69, 351
of Zinc, 360

Glauber's Salt, 27, 169, 213

Gold, 37, 112, 223
refined by Cementation, 258
imitated, 71, 364

Golden Sulphur of Antimony, 68, 318, 334

Grain, in Salt Petre working, 183

_Gravelle_, or _Gravellee_, 517

Green Precipitate, 60
Vitriol, 49, 111
fluid, 278

Guaiacum Wood analyzed, 440

Gums, 81
analyzed, 476

Gum Resins, 477

Gypsum, 169, 404

H

Head of an Alembic, 128
Blind-head, 130

Heart-burn, 568

Heat, reverberated, melting, forging, lamp-heat, &c., 134

_Hepar Sulphuris_, 21

Hoffman's Anodyne Mineral Liquor, 500

Honey analyzed, 474

Hops, 484

I

Icy Oil of Vitriol, 18, 173

Infernal Stone, 40, 255

Infusion, 492

Ink, sympathetic, 353

Iron, 47, 114, 270
red-shire and cold-shire, 272
pig-iron made malleable, 273
converted into Steel, 48, 274

Juices by expression, of Plants, 102, 383
of Animals, 106

K

Kermes Mineral, 68, 332

Killed Mercury, 305

L

Laboratory, of a Furnace, 135

_Lac Calcis_, 30, 520
_Sulphuris_, 21

_Lapis infernalis_, 40, 255
Calaminaris, 71, 118, 357
purified, 362

Lead, 53, 115, 286
White, 92, 553

Lees of Wine, 515, 517

Libavius, his smoking Liquor, 61, 285

Lime, Lime-stone, 29, 520
slaked in the air, 30

Lime-water, 30, 520

Liquescent Salts, 17

Litharge, 54, 294

Liver of Sulphur, 21, 73
of Antimony, 67, 325
of Arsenic, 75

_Luna Cornea_, 57, 256, 257

Lunar Crystals, 40

Lutes, 147, 148

M

Maceration of Plants, 415

Magistery, 22, 36
of Sulphur, 22
of Bismuth, 70, 352
of Coral, Pearl, Crab's-eyes, &c., 549
of Lead, 553

Magnesia, 186

Malt, Malting, Malt-liquor, 479, 486

Manna, 475

Marcasites, 109

Matched Wines, 482

_Materia perlata_, 65, 67, 328

Matrass, 129

Mercury, 58, 115, 298
revivified from Cinabar, 62
obtained from Lead, 296, 298

_Mercurius præcipitatus per se_, 58, 302
_dulcis_, 61, 312
_vitæ_, 64, 342

Mercurial Earth, 25, 34

Metals, 37
perfect and imperfect, 35, 37

Metallic substances, 35

Milk, 108, 393, 562

Minerals, 108

Minium, 53

Moist way of parting Metals, 42

Mortar, 30

Mother-water, 186

Muffle, 144

Must, 482

Mustard-seed analyzed, 446

N

Neck of the Alembic, 128

Neutral Salts, 15
having Lime for their basis, 33
Arsenical, 73, 377
of Vinegar with absorbent Earths, 92

Nose of the Alembic, 128

Nitre, 22, 181
its basis, 185
fixed or alkalizated, 23, 187, 379
quadrangular, 27, 220

Nitrous Salts with an earthy basis, 22
with Lead, 297
with Mercury, 307

O

Object of Chymistry, 1

Ochre, 50

Oils, in general, 76
Mineral, 79
Vegetable, 80
Animal, 82
Fetid, or Empyreumatic, _ib._
Fat, by expression, 102, 386
by decoction, 410
Essential by expression, 388
by distillation, 412, 444
_per descensum_, 418
rectified, 422
falsified, 425

Oils fired by Acids, 426

Oil of Vitriol, 18
Icy, 18, 173

Oil-varnish, 87

Oil of Tartar _per deliquium_, 94
of Lime, 208, 611
of Salt, 216
of Mercury, 304
of Amber, Volatile, 467
of Eggs, by expression, 586, 588
of Myrrh _per deliquium_, 587

Ores, 109

Orpiment, 75, 118, 369

P

Panacea of Mercury, 61, 314

Pancreatic Juice, 108

Parting Process, in the humid way, 42, 250
in the dry way, 258

Pearly matter, 65, 67, 328

Pelican, 130

Penny-weight, 56

_Petroleum_, 79

Philosophic Wool, 70
Spirit of Vitriol, 343

Phlogiston, 7

Phosphorus of Urine, 26, 77, 78, 198, 446, 447
Homberg's, 618

Pig-Iron, 48, 271

Plaster, 407

_Plumbum corneum_, 57

Point of Saturation, 16

_Pompholyx_, 70

Potential cautery, 33

Powder-blue, 371

Precipitant, 66

Precipitation, 22, 36

Precipitate of Sulphur, 22
of Gold, purple, 284

Precipitate, Red, 60, 307
Green, 60
Yellow, 61
White, 307

Precipitated _Aqua Fortis_, 44

Prince's Metal, 71, 364

Principles of Bodies, 2

Principle of Odour, 408, 413

Proof of Spirit of Wine, 484

_Pulvis Algaroth_, 342

Purification of Nitre, 185
of Spirit of Nitre, 194
of Spirit of Salt, 213
of the Sedative Salt, 222
of Silver by Nitre, 248

_Pyrites_, 110, 160
Yellow, 110
White, 111, 118
Copper-coloured, 111

Q

Quadrangular Nitre, 27, 217

Quartation, 43, 251

Quartz, 147