ALC
A L G
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Or, with lei's trouble, add one part of thealkali to four parts of brandy, and dillill afterftanding together for about a day •, but the for-mer procefs is the beft.
Burnt alum, dried Glauber’s fait, or decrepi-tated common fait may be very convenientlyfubftituted for the carbonated alkali.
Hot, dry, cauftic alkali is Hill more efficaciousin feparating the water from the alcohol, which,carefully diftilled, is extremely pure. But caufticalkalies, as well as lime, decompofe fo much ofthe alcohol, in the way that will be afterwardsmentioned, as to render it both a wafteful pro-cefs and one that requires more care in con-ducing it.
By the above means the levity and proportion-able dephlegmation of alcohol may be broughtfrom the fpecific gravity of .825 at 6o° of heat,to about .813 0 or perhaps ftill higher. Maltfpirits yield as ftrong and pure an alcohol aswine brandy.
Various methods have been employed forafcertaining the ftrength of ardent fpirit, butthis is attended with more difficulty than mightat firfl be imagined. Long habit will enable aperfon to judge with tolerable accuracy by thetafle, and the frothinefs and fize of the bubbleswhen fhaken, but this is obvioufly liable toerror. The tefl of burning the fpirit has longbeen ufed, and with proper precaution it maybe brought to fome degree of accuracy. It hasbeen already mentioned that a very pure alcoholwill burn away without leaving any refidue,and that the weaker the fpirit is, the morewater will be left after combuftion. In manycountries this trial is actually performed in thefollowing Ample manner. d A cylindrical filvercup, properly gradulated and made for this pur-pole, is filled to a known height with the fpirit,which is then kindled, and is fuffered to bumtill the flame goes out, after which the quantityof watery refidue is noted. Pure alcohol leavesnone, rectified fpirit of moderate ftrength about2j per cent, French brandy about 5 6, commongood malt fpirit about 65, and the like. Theprincipal imperfection of this method, is thedifficulty of always performing the experimentunder fimilar external circumftances: and be-fides it is by no means proved that the com-buftion of compound fpirits will follow thefame rules as that of Ample mixtures of alcoholand water. In this trial the refidue Hill containsa portion of alcohol, the combuftion ceafingbefore all the fpirit is burnt off; but on the
other hand, fome of the water muft neceffarilyhave been evaporated by the heat of combuftion.
Another trial, though extremely incorrect,is to pour a few drops of the fpirit on a veryfmall heap of gunpowder, and kindle it. Thefpirit firft burns as ufual, and when the laftportion is burning off, tire powder explodes,if the fpirit has not been too watery to leavethe powder very damp. Cotton wool burns inlike manner at the end of the combuftion ofthe fpirit, if not too damp. But it is wellknown that a little heap of powder drenchedwith even a ftrong fpirit, will not take fire,and a large heap will explode if only a fewdrops of a watery fpirit is ufed. Befides, thefetefts, were they accurate, would only indicatetwo degrees of ftrength, that which would firethe powder, and that which would not.
Another teft, fufficiently accurate for a rougheftimation of the ftrength of the fpirit, is toffiake it in a bottle with fome dry carbonat ofpotaffi, and to judge of its ftrength by thequantity of water which the alkali attractsfrom it.
A fpirit that fwims in olive oil has fometimesbeen confidered as proof, and this method isarilually ufed in the manufarilure of rum, butthis tell alfo only indicates two degrees.
The only mode of afcertaining the relativeftrength of every fpecies of ardent fpirit, withany confiderable accuracy, has been by deter-mining its fpecific gravity; and the high publicimportance of the fubject in countries wherethe qonfumption of fpirits adds a vaft fum tothe public revenue, has been the means of infti-tuting many very interefting feries of experi-ments to this purpofe.
As our limits will not allow a complete noticeof all that has been done on this fubjerit indifferent countries, we ffiall principally confineourfelves to the very minute, accurate, andevery way excellent feries of experiments madefor the Honourable Board of Excife, by SirCharles Blagden , affifted by Mr. Gilpin, andpubliffied in the 79th and 8 2d volumes of thePhilofophical Tranfaffions.
Their objeril was to determine by a ritualexperiment, the fpecific gravity of mixtures ofdifferent proportions of alcohol of a determi-nate ftrength, with pure diftilled water atdifferent degrees of the thermometer; and thefeexperiments were carried to a minutenefsmuch more than neceffary even for the highduties now levied on fpirits, where a trifling
c Blagden Phil. Tranf.