X Lixivium tartari.

(a) See Dr. Home's Experiments on bleaching. - It has been suspected that the matter in Russia potash, which seemed from Dr. Home's experiments to be quicklime, is no other than the earth of the vegetable ashes themselves, which earth, by strong calcination, such as this kind of potash is said to undergo, assumes some of the most striking characters of true quicklime. Since the eftablishment of the American manufacture, the Russia sort has in this country fallen so much into difuse, that it is very difficult to procure a specimen that can be depended on as genuine. What has been sent to me as true Russia potash (and which indeed has greatly the appearance of what used to be fold under that name) on being elixated with water, leaves a large quantity of earthy matter, greatest part of which dissolves readily in aquafortis. This solution has exactly the same taste with a solution of chalk made in the same acid: on dropping into it a little vitriolic acid, the liquor grows instantly milky, and a copious precipitation ensues. This precipitability by the vitriolic acid is one of the properties of calcareous earths, which the earth of vegetables has not been found to acquire by any degree of calcination; and therefore we may conclude that in the making of this potash real quicklime is mixed, in very large proportion.

Quicklime remarkably increases the activity of all these salts; enabling them, in a liquid or dilute form, to dissolve oils, fats, etc. far more powerfully than either the lime or alkali by themselves; and in a solid or more concentrated one,

Sal alkalinus fixus vegeta-bilis purifi-catus Ph. Ed,

Kali praepar-Ph. Lond,

Aqua kali Ph. Land, one, to act as caustics. For these purposes, the London college directs four pints of water to be poured to six pounds of quicklime, which are to stand together for an hour: then as much more water as will make the whole four gallons, with four pounds of alkaline salt, are to be added, and the whole boiled for a quarter of an hour, when it is to be suffered to cool, and strained off. The liquor is known by the name of soap lye, and ought to be of such a strength, that an exact wine pint may weigh just sixteen ounces troy. If it excites any fermentation with acids, more quicklime is to be added. The common lyes of our soft-soap makers are considerably stronger than this: Dr. Pemberton observes, that their lyes will be reduced to the strength here proposed, by diluting them with somewhat less than an equal measure of water. * In the Edinburgh pharmacopoeia this preparation is thus directed. Eight ounces of fresh quicklime are put into an iron or earthen vesel with twenty-eight ounces of warm water. When the ebullition is over, six ounces of pure vegetable sixt alkali are added, and after perfect mixture, the vessel is covered and suffered to cool. The matter is then poured into a glass funnel, lined with a linen rag, and is set to drain into a glass bottle as long as any liquor will run. Some more water is then to be poured to the matter in the funnel, which will drain through it; and this is to be repeated till three pounds of liquor are procured, which is to be shaken together, and kept in a well flopped phial, (a)

(a) Pure alkaline salt requires commonly about twice its weight of quicklime to render it completely caustic, Complete causticity is known by the lye making no effervescence with acids. A redundance of lime is known, by the lye growing milky on dropping into it a little common alkaline lye, or on blowing into it with the breath through a glass pipe.

Aqua kali Ph. Lond.

Lixivium causticum Ph. Ed.

The dry salt obtained by evaporating these lyes is a strong and sudden caustic: for the greater convenience of using, it is urged in a crucible with a strong fire, till it flows like oil, then poured upon a flat plate made hot, and whilst the matter continues soft, cut into pieces of a proper size and figure, which are kept in a glass vessel closely stopt. It deliquiates much sooner in the air, and dissolves more readily in watery liquors, than the milder alkalies, and in this consists its principal inconvenience; being apt to liquefy so much upon the part to which it is applied, as to spread beyond the limits in which it is intended to operate. This inconvenience is avoided, by boiling down the soap lye only to one third † or fourth ‡ part, and then, while the liquor continues boiling, sprink-ling in, by little and little, so much powdered quicklime as will absorb it so as to form a kind of paste†: or, more accurately, in the proportion of five pounds four ounces, to sixteen pints of the original lye ‡: the addition of the lime in substance renders the preparation less apt to liquefy, and hence more easily confinable within the intended limits, but at the same time proportionably more slow in its operation.

2. Sal alkalinus volatilis. Volatile alkaline salt: obtainable, by distillation with a strong fire, from all animal matters, from foot, and in small quantity from most vegetables: producible also in animal substances, very plentifully in urine, by putrefaction, and in this case separable by distillation with a gentle heat-When the salt is once formed, whether by ignition or putrefaction, it gradually exhales in moderately warm air; and rises sooner in distillation than highly-rectified vinous spirits, condensing about the sides of the recipient into crystalline concretions. It requires for its solu-tion three or four times its weight of water.

Kali purum Ph, Lond.

Causticum commune acerrimum Ph. Ed.

† Causticum commune mitius Ph.Ed.

X Calx cum kali puro Ph. Lond.

These salts are in smell as well as taste very penetrating and pungent: they are the only concrete salts that in their pure state emit sensible effluvia. They dissolve oils, resins, fats, etc. more languidly than the fixt alkalies, on account perhaps of their not being susceptible of any considerable heat, by which their men-strual power might be promoted. In the bodies of animals, they operate more powerfully than the fixt, both as resolvents and stimulants; are more disposed to direct their force to the cutaneous pores, and less to the grosser emunctories; and act more remarkably upon the nervous system. They are particularly useful in lethargic and apoplectic cases; in hysterical and hypochondriacal disorders, and the languors, head-achs, inflations of the stomach, flatulent colics, and other symptoms attending those distempers, especially in aged persons and those of a phlegmatic habit: in languors and faint-ings, their stimulating smell gives oftentimes immediate relief. In some kinds of fevers, particularly those of the low kind, accompanied with a cough, hoarseness, redundance of phlegm, ana lentor of the blood, they are of great utility; liquefying the thick juices, raising the pulse, and exciting a salutary diaphoresis. In putrid fevers, scurvies, and wherever the mass of blood is thin and acrimonious, they are hurtful: for though they powerfully resist the putrefaction, of animal substances, that are detached from the vital oeconomy, yet, in living animals, one of their primary effects is a colli-quation of the humours, which in its advanced state is very nearly allied to the advanced state of putrefactive colliquation: their immoderate use has brought on high scorbutic symptoms, resembling those of the true putrid scurvy (a). These salts are most commodiously taken in a liquid form, largely diluted; or in that of a bolus, which should be made up only as wanted, the salt soon flying off. The dose is from two or three grains to ten, twelve, or more.