third, the Rigidity of the Particles of the Menftruum. The fourth is Fire, which agitates and inforces the Action of the Particles of the Menftruum. But the infufficiency of mechanical Power for producing the Effects of many Menftruums, the Author fhews by a Rationale; adding a rehearsal of those Menftruums wherein fomething more is neceffary: fuch are Water and aqueous Bodies, Salts, and faline Bodies, as Sapo's, &c. alfo Earths, and terrestrial Bodies: Sulphurs, and Refins.

For Oils, and oily Menftruums, he fhews that oily Menthe Action of Fire, Water, Acids, Alkalies, andЛtruums. the Spiritus rector, have a great share in the Effects thereof. For fpirituous ones, as Alcohol, the an- Spirituous; tient Chemists make a great Secret of it, infomuch that Weidenfeld is of opinion this is the only thing they conceal.

Those popularly called fpirituous Menftruums are different from Alcohol, and are confidered by the Author under the two Heads of alcaline and acid Spirits. The alcaline fubdi- Alcaline. vide into those which are fimple, as Spirit of Sal Armoniac; and compound. For the acid kind, tho' ufually by Chemifts confidered as Spirits, the Author fhews from feveral Reasons, that they belong rather to the Clafs of Salts, and therefore refers their Confiderations to that head.

Salts make a capital Article in the Bufinefs saline. of chemical Menftruums. When pure, they confift of Elements too minute to be perceivable even by a Microscope; fo that no Light can be had thence with regard to their Figures. The ufual Manner of confidering them, is as affociated with other Bodies, particularly Water and Earth; in which State it is, that they chiefly make the Object of chemical Operations.

Salts

Fixed Alcali.

Kinds.

Salts then may be divided into such as either differ in their Principles, or in the Body or Bafis combined with them, or in both: with regard to the former, Salts and confequently faline Menftruums are subivided into,

66

1. Fixed Alcali; the Characters whereof are, that it is of a vegetable Origin, procured "from Plants by burning them to afhes; re"mains long fixed in the Fire; diffolves in a "moist Air, and will not keep long dry in the "clofeft Veffel; affords a hot pungent Savour, "accompanied with a Senfe of Acrimony, and "even fomething of an urinous Taste (whence "the Salts of this Clafs are frequently, tho' with"out much Propriety, called urinous Salts ;) that "when burnt, it yields no Smell, on account of "its fixity; when mixed with Acids, makes "an Ebullition, and grows hot; mixed with "the Juices of Tournfol, Roses, or Violets, turns "them from a green Colour to blue: when ap

plied to the warm Body, raises an Inflamma"tion, and Eschar. And lastly, that it has a "Faculty of deterging and cleanfing Bodies."

The Salts of this Clafs are procurable in greater or lefs quantity from all Plants; moft plentifully from that called Kali, and least from thofe which yield a pungent Smell, as Leeks, and the like. Add, that not being native, but the mere Creatures of the Fire, they are liable to be destroyed again.

Fixed Alcalies are various, according to the Degrees of Purity wherein they are procured ;the most ordinary is procured from Pot-Afbes, by diffolving them in hot Water, and skimming off the Salt that fwims a-top. Another is that procured from Wine-Lees, by burning them; another from Tartar by Distillation;

others

others from Salt-petre; others from Tartar and Salt-petre; others from Nitre and Antimony. Alcalies are alfo of different Degrees of Purity, according as more or lefs of the acid Salt, Oil, and Earth of the Vegetables, is left adhering to them; as alfo according to the different Bodies added to them.s

Some other Properties of fixed Alcali, are, Powers. its Power of attracting Water, and retaining it when attracted; a Power of repelling Air, or perhaps attracting it; of mixing greedily with Alcohol; of attracting diftilled Oils, as well as thofe procured by Preffion; and of attracting Acids of all kinds, tho' fome more than others. Add, that the Power of Alcali, as a Menftruum, has its Bounds, for that it has no Effect upon pure Quickfilver, nor even upon the purer Metals, as Gold and Silver.

The Author fubjoins feveral Problems, or Points of Inquiry concerning Alcalies; as, whether it be poffible for any Alcali to remain long in the Air, without lofing its alcaline Characters; and whether it will not always, by its meeting with acid or oily Bodies therein, turn into a neutral Salt, or a Sapo? Whether the fame does not happen in the Bodies of Plants, or Animals; and whether hence does not every day arise a great Quantity of compound Salts, &c.

The fecond Clafs of faline Menftruums are Volatile volatile Alcalies, ufually fuppofed to owe their Alcalies. origin to the Putrifaction, or Diftillation of P. 803, vegetable and animal Bodies. The Powers and Properties of these are much the fame as thofe of the fixed Kind; except that they No. XVI. 1732. VOL. III.

a

Cc

act

Acid, 804.

Kinds.

Neutral.

act with a lefs Degree of Heat, and that if the Fire be raised beyond a certain Point, they

evaporate.

The third Clafs confifts of acid Menftruums, which are rarely found in a folid Form, except in the effential Salt of four Plants, or Tartar. Whether there be any in Animals, is difputed; as alfo, whether thofe in Vegetables be native, or produced therein by Fermentation? At leaft, Fermentation appears greatly to promote the occult Acid lodged in Vegetables.

The Acids produced by Fermentation, are divided by the Author into Vinofe and Acetofe; which latter are of fuch importance in Chemistry, that all Menftruums are frequently called by the Name of Aceta Philofophorum. Again, foffil Acids, proper for diffolving Gold, Silver, &c. are either native, which are very rare; or fixed, as thofe found in Sulphur, Alom, Vitriol, Nitre, and Sea-Salt. From the whole, the Author deduces feveral Corollaries concerning the Nature of different Menftruums; and fhews more particularly their Agreement and Difagreement, both with themfelves, and with Alcalies.

The fourth Clafs confifts of neutral faline Menftruums; fuch are Sal Ammoniac, Sea-Salt, Salt-petre, Borax, and divers other compound Salts, the menftrual Properties and Effects of each whereof, the Author fhews at large; clofing the Chapter with a Number of Corollaries concerning the Powers, Properties, and Action of Menftruums; wherein he liquidates many Points, ftarts divers new Views and Hints, from the Facts delivered in the course of the Hiftory.

For

For the universal Menftruum or Alcabeft, Alcabeft. the Author makes a particular Article; wherein P. 848. he gives its Hiftory at large; deducing its Name, Etymon, Synonima's, Origin, Powers, Manner of Action, and Effects; Immutability, and Volatility. Inquires into the Matter of which the Alcaheft is to be made, viz. whether SeaSalt, the Bafis of the Sal Circulatum minus; or Mercury, the Bafis of the Sal Circulatum majus; or fome Metal or Earth.

The Theory ends with an account of the chemical Furniture of Veffels and Utenfils.

869.

In the Veffels the Conditions required are; Veffels. that they be fit to contain the Object, and to fuftain the Force, of Fire, and other diffolving Agents. Either the Matter or Form of these is confidered. The Matter is either Wood or Stone, or Potters Earth, or Glass, which laft has extraordinary Conveniencies: for the Figure, it is various, according to the ufes; and may be reduced to the two Heads. of cylindrical Veffels, which rarely come in ufe, and conical ones: in which latter, fome have the Figure of the Cone erect, used to hinder the afcent of the Bodies expofed to the Fire; others have it inverted, or placed on its Vertex, ufed in feparating the fixed Parts of Bodies from the lighter and more volatile. The Principles both of Geometry and Hydraulicks, on which thefe different Structures depend, are explained by the Author; as also the feveral Inftruments themselves, viz. the Retort, Cucurbit, Matrass, Long-neck, Receiver, Alembic, Pelican, &c.

He proceeds to confider Lutes, or "thatLutes. 881. "tenacious fort of Bodies, which grow folid as "they dry, and ferve for clofing the Junctures

C.c 2

" of