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The method he therefore invented is this: fill a flill half full with the fpirit prepared for alcohol in one or the other of thefe ways, add to it half a pound of pure decrepitated, and perfectly dried fea-falt; put this in hot, then place on the head, and carefully lute the junctures ; leave this for twelve hours in a heat fo fmall, as not to make the alcohol boil, then diftil off the fpirit ; keep the firft two ounces apart, becaufe fome aqueous vapour may have happened to lodge in the head, or worm of the ftill, which this cer- tainly wafhes off; after this receive two thirds of the fol- lowing alcohol into a pure dry glafs-veficl, and keep it per- fectly flopped ; then draw off the remainder, and keep that by ftfelf : there will remain a moift fait in the ftill, which has attracted the aqueous matter of the alcohol, and held it fo down, that it could not rife by the heat of boiling water, which is all that muff be ufed in this diftillation; and the fait having been firft decrepitated, never makes any change in the alcohol, by adding any thing thereto. By this means an alcohol is prepared perfectly pure, and. fit for all the ufes of chemiftry.
The alcohol thus perfected is the lighteft of all fluids next to air ; it is extremely pellucid, thin, and fimple, and is to- tally inflammable, burning without fmoak, and without leaving any feces behind. It has no difagreeable fmell in the burning, remains the fame after diftillation, is very ex- panfive with heat, eafdy boils over the fire, is of a grateful odour, and agreeable tafte. This fluid inftantly coagulates all the juices of the body, except pure water and urine; it hardens the folid parts of the body, and preferves both the folids and fluids from putrefaction, or fpontaneous refolu- tion ; it preferves the bodies of birds, fifties, infects, and other animals fufpended in it, perfect for ages. It mixes almoft uniformly with water, vinegar, any acid liquors, oils, and pure volatile alkaline falts ; and diflblves gummy and refinous bodies. Hence we are acquainted with no li- quor, either natural, or produced by chemiftry, which will mix with more bodies.
It is in particular an excellent vehicle for the prefidingypzrzV of vegetables, as by means of it that fpirit may be com- modioufly extracted from its own body, and fitted for me- dicinal purpofes. In the living human body it wonderfully raifes, gratefully affects, and ftirs the animal, natural, and \\ti\ fpirit s, whence it gives encreafe to the ftrengtb, fenfes, and agility ; but by its power of coagulating the blood, fe- rum, and other juices, it may kill by being imprudently taken. It inftantly flops bleeding, by at once contracting the veffels, and coagulating that blood which it touches at the mouths of them ; and hence it is a fudden and powerful remedy in thefe cafes.
If the parts of animals, or vegetables, fufpended in alcohol, contain any thing oily in them, the alcohol immediately extracts it from the matter, which thence becomes fhrunk, wrinkled, and withered ; but fmall birds with their feathers on, and fifh that are well covered with fcales, remain per- fectly preferved in their. recent form, by being plunged in hot alcohol. When they have been long enough in the fpirit to be perfectly penetrated by it, they may be taken out and dried in a flack oven, and afterwards put up in empty glaffes well flopped, where they will remain beautiful fpecimens for ages. Boerh. Chem. Part 2. p. 126. ■ Alcohol being required on many occafions to be perfectly pure, and free from the lcaft drop of water, it may be pro per to add here the true and infallible rules of judgin when it is fo. Thefe are the following.
1. If any oil be contained in the alcohol, it turns milky on being mixed with water.
2. If it contains any acid; when a little of it is mixed with fpirit of fal armoniac, there will be an effervefcence, otherwife there will be only a fimple coagulation ; and if any thing alkaline be contained in it, this will be difcovered by the mixing it with acids; as for the other falts, they are fcarce ever contained in the alcohol.
Thefe are the tefts of fuch admixtures, but they are the leaft common ; water is the moft frequent, and moft to be fufpectcd in it, and this is the moft difficult to be difco- vered. To this purpofe a little of it is to be fired in a fpoon in a ftiH place, where there is no wind moving, and if no water be left in the fpoon, this is a fair ftep toward its an fwering expectation : this, however, alone is by no means to be depended upon. Gunpowder alfo put into a fpoon, and covered with alcohol, if when the whole is burnt away it takes fire, gives another proof that there is but little water contained in it; but this does not prove, any more than the former, that there is none. After thefe trials, the fureft is this : take a round chemical vial, capable of hold- ing four or fix ounces, and having a long neck ; fill two thirds of this with alcohol, and add to it a drachm of pure fait of tartar well dried, and heated very hot; ftiake them well together, and hold them over the fire to make them juft fo hot, as that the alcohol does not quite boil. If after this the fait of tartar is perfectly dry, we may be aiWed that the alcohol contains no water, or if any, not to be dif- covered by any experiment hitherto known, unlefs by the water collected from its flame when perfectly burnt. 1
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If after the fait of tartar has remained dry ever fo long at the bottom of this pure alcohol, only a drop or two of water be added to it> the fait immediately becomes moift, ant j hangs about the bottom and fides of the veffel. To this it is to be added, that this pure alcohol, when diftilled, gi Ves no appearance of itfelf, either in the head or neck of the alembic, nor on the fides of the receiver ; neither appear- ing like the aqueous fluids in moift drops, nor like good fpirit of wine, running in veins, but remaining invifible to the eye, except at the bottom of the receiver. This pro- perty of alcohol was known to the antient chemifts, as ap- pears by their writings. Bocrbaave's Chemiftry, Part 2. p. 127.
Water is a folvent to alcohol, or fpirit of wine, in certain circumftances, but not fpontaneoufly, or in all mixtures. If water be gently poured into it, it does not diffolve it, or mix itfelf with it, but falls through it, and collects itfelf into a feparate body at the bottom of the veffel ; as foon, however, as they are fhook together, the alcohol begins to blend with the water, though at firft, or with a little mak- ing, it only is difperfed in form of unctuous veins through the body of the water, but by continued fliaking, they perfectly unite. As alcohol, therefore, is a pure vegetable oil, produced by a perfect fermentation, its nature is thus perfected, fo as not only to burn in the fire, but to mix per- fectly and eafily with water : but water impregnated with falts will not diffolve alcohol, for a ftrong folution of fait of tartar in water, will not be brought to mix with alcohol by any fhaking, nor even by boiling together; but as foon as the mixture has flood a little, the fpirit gets to the top, and remains perfectly unmixed with the water. Salt of tartar unites itfelf more intimately than many other falts to water; and if another fait, which more eafily feparates from water, fuch as Epfom fait, be, in the place of fait of tartar, dif- folved in water, though the folution be ever fo ftrong, the liquor will diffolve alcohol; and on their being mixed to- gether, the whole will become turbid and white, and the fait will be precipitated in cryftals. Boerbaerue's Chem. Part 1. p. 452.
Water has alfo this remarkable quality, that if mixed with alcohol, in which any effential oil lias been difTolved, it fe- parates the oil from the alcohol. Thus if oil of cinnamon be diffolved in pure alcohol, and water be let tail into this folution, the mixture prcfently becomes white and opake, though it was perfectly pellucid before; and the oil fepa- rates itfelf from the alcohol, and gathers into a body. Hence it appears, that alcohol is difqualified by water for the dif- folving of thefe oils ; that it alfo more eafily and readily unites with water than with them ; and finally, that thefe effential oils, while they appear to be wholly diffolved in the alcohol, and no longer look like oils, but like fpirit, yet are really oils, and eafily feparable in their true form. Boerh. Chem. Part 1. p. 453.
Proof fpirit cannot be ufed for burning in lamps, for dif- folving rofins, for making varnifh, and there are a great number of tinctures, folutions, and mixtures^ for which it cannot ferve ; but alcohol, befide its ready ufe in the medi- cinal way, may, when the fpirit is of a proper kind, be made into punch, and all other mixtures, with more purity, and a great deal more certainty and exactnefs in point of ftrength. Shaw's Effay oh Diftillery. Colouring of Spirits. The art of giving to diftilled liquors a colour, which takes off their watery appearance, and gives them a refemblance of the foreign brandies, £5V. The colouring is not only necefiary on this account, but as we ufually efteem the Jpirits by the proof of the crown of bubbles, it is found that the clean rectified fpirit will not afford this proof till it has received its dofe of the colour. The diftillers difpenfe this colour in any proportion that they find convenient or neccflary : it is always yellow, but according to the degree differs extremely in deepnefs, from the paleft ftraw colour to the deepen: orange. This art of colouring was firft introduced, from obferving that all the fine and foft foreign brandies, that had the mellownefs ne- ceffary to their perfection to the tafte, had alio a yellow co- lour. The colour, in this cafe, has indeed nothing to do with the flavour ; but that being kept in cafks the fame age that was neceffary to give them this mellownefs, would alfo give them a colour from the wood. It was hence fuppofed, that the particular excellence of the foreign brandies de- pended on the woody colour, and accordingly have been taken to give the fame colour to our fpirits, by various me- thods.
The way of obtaining it, by many years ftanding in the calk, proved too tedious for our hafty workmen, and ac- cordingly they provided means of giving it extempore by ftrong tinctures of feveral ingredients ; the chief of which are logwood, faffron, Japan earth, treacle, burnt fugar, and oak chips : the three former of thefe have but little to re- commend them, but the others are found very ready, and very proper for the ufe.
Treacle gives a fine colour, not much unlike that of the foreign brandies, and being neceflarily ufed in a large quan- tity, as its colour is but dilute, it not only mends the bubble,
