Elements of the Theory and Practice of Chymistry, 5th ed.

by Pierre Joseph Macquer

Then raise your fire more boldly. The acid Spirit will continue to rise, and will be accompanied with a black, fetid, empyreumatic, ponderous, and very thick Oil. Urge the fire to the utmost extremity, so that the retort may be of a perfect red heat. This violent fire will raise a little Volatile Alkali, besides a portion of Oil as thick as pitch. When the distillation is finished, you will find in the retort a black, saline, charred matter, which grows hot when wetted, attracts the moisture of the air, runs per deliquium, and hath all the properties of a Fixed Alkali.

This mass, being exposed to a naked fire in the open air, burns, consumes, and is reduced to a white ash, which is a fiery, caustic, Fixed Alkali.

OBSERVATIONS.

The matters qualified to produce a spirituous liquor by fermentation, do not all contain the just and accurate proportion of Acid necessary to constitute an Ardent Spirit. Many of them, the juices of fruits for instance, and especially that of the Grape, are replete with a super-abundant quantity of Acid, more than concurs to form that product of fermentation. This super-abundant Acid, combined with some of the Oil and earth contained in the fermented liquor, produces a sort of Salt, which hangs for a while suspended in that liquor, but after some time, when the Wine stands quiet in a cool place, separates from it, and forms a stone-like incrustation on the inside of the vat in which the Wine is kept. This matter is called Tartar.

The Lees of Wine resemble Tartar, in as much as they contain, and yield when analyzed, the same principles; but they differ from it in this, that they contain, moreover, a greater quantity of earth, of phlegm, and a little Ardent Spirit, which are only mixed, but not united, with the tartarous Acid.

The residue, or sort of extract, which remains in the cucurbit after Wine hath been deprived of its Ardent Spirit by distillation, hath also a great conformity with Tartar. It even contains that portion of Tartar which remained suspended in the Wine at the time of its distillation: and accordingly this residue of Wine, being analyzed, yields the same principles with Tartar.

Hence we see, that liquors, which have undergone the spirituous fermentation, consist of an Ardent Spirit and a Tartarous Acid suspended in a certain quantity of Water.

In the analysis of Tartar there are several things worthy of notice. The first is, the vast quantity of Air that this mixt body yields when it begins to be decomposed. The chief difficulty attending its analysis arises from this air; which issues out and exerts its elastic force with such impetuosity, that all the precautions above-mentioned are no more than necessary to prevent the bursting of the vessels.

The singular nature of the thin limpid Oil, which rises with this air, after the first acid phlegm, deserves likewise our particular attention. This Oil is one of the most penetrating we know. Boerhaave, who distilled Tartar without having a vent-hole in his receiver, was obliged, in order to prevent its bursting, to apply it to his retort with a lute so weak that most of the elastic vapours might perspire through it; and he observed, that, though the neck of his retort entered above five inches into the mouth of his receiver, and was luted on as closely as possible with such a lute, yet this light Oil of Tartar constantly returned back again, as it were, and pervaded the substance of the lute, so that a good deal of it dropped in a dish placed on the outside on purpose to receive it. This Oil is probably rendered so active and subtile, only by having been exceedingly attenuated by the fermenting motion. This experiment is one of those which sufficiently prove the necessity of employing receivers having a small vent-hole, that may be opened and shut as occasion requires.

The last remark we shall make, on the productions of Tartar by distillation, relates to the caput mortuum found in the retort when the operation is finished. This residue is very different from that which other vegetable matters afford: for, when they are decomposed in close vessels, they leave nothing but a mere charred matter, in which no saline property appears, and from which no Fixed Alkali can be obtained, but by carrying their analysis to the utmost; that is, by burning them in the open air. Tartar, on the contrary, only by being distilled in close vessels, without burning it afterwards in the open air, is changed into a substance which hath all the properties of a Fixed Alkali. This is probably owing to the Tartar's containing the principles requisite to form a Fixed Alkali in a much greater quantity than they are to be found in any other substance. As Tartar thus alkalizated in close vessels still contains much inflammable matter, it might be employed with advantage as a reducing flux, in several operations of metallurgy.