ALCOHOL.— Rectification of Spirit.

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marks about 46 per cent, over proof, and is aboutthe strength of spirit of wine in general; of this,about 80 gallons are obtained from 100 gallons ofordinary whisky, of 25 per cent, over proof. Afurther distillation affords a liquid of spec. grav.0-820, which is the strongest spirit that can be ob-tained by mere distillation.

The presence of fusel oil in alcohol may be recog-nized by its taste, especially after dilution with a largequantity of water; and by its smell, particularly afterrubbing the alcohol between the hands, or allowingpart of it to burn away. Vogel finds that alcoholto which nitrate of silver solution has been added,when placed in the sunshine, remains perfectly brightand clear; whereas, if it contains fusel oil, it becomesvery strongly reddened.

Gobel states that the origin of any particularalcohol can be ascertained by the following means,even when no particular odour can be detected byordinary examination. A solution of 1 part of potas-sium hydrate in a small quantity of water is added to160 parts of the brandy or spirit to be examined;after agitation the whole is reduced by slow evapor-ation to 15 parts. An equal volume of dilute sul-phuric acid is then added, and the mixture wellshaken. In the case of potato spirit the vapourevolved has a very disgusting odour, and produceswhen inhaled spasmodic contraction of the throat,headache, and giddiness. In the case of malt spiritthe odour resembles that of sour dough, and pro-duces a similar though less powerful physiologicalaction, ltum, arrack, brandy, have when treated inthis way each their characteristic and perfectly dif-ferent odour.

Caustic potassa—under the name of grey salts—or soda, is added to unite with the oil; pearl-ash—white salts—is employed with the view of combiningwith the water, as well as to take up the fatty oroily impurities. The alkali combines with the oil,giving a soap which remains in the still, while thespirit passes off divested of its impurities. It hasbeen ascertained that when carbonated alkali is used,the distillate contains a sufficient amount of the saltto affect reddened litmus and turmeric; hence thismethod cannot always be followed.

When calcium chloride, caustic lime, sodium sul-phate, potassium acetate have been employed, eitherfor the purpose of uniting with water or oily matterin the liquors, portions of these bodies are, accordingto the statements of Dubue, invariably found in thedistillate. The same authority states, that whenspirit was distilled over calcined alum, the condensedliquid reddened litmus paper; but when sulphuricacid was added in small quantity to the spirit, theproduct which came over was found to be quitepure. Alumina, or aluminous clay, well washed anddried, was found capable of extracting small quanti-ties of water from spirit, and no portion of it passedover into the receiver.

Charcoal is a means by which the disagreeableflavour of spirituous liquors is removed. It has beenmade the subject of investigation by many chemists,among whom Lowitz ascertained that, by distilling

common malt spirit over charcoal, or by merelyagitating the two together, its peculiar bad smell wasremoved. He performed ten experiments with onepound of common spirit for each operation, and avariable quantity of charcoal, from half a drachm tofive ounces, with the following results:—

Half a drachm of charcoal scarcely altered the smell,and the liquor did not clear for six months.

One drachm of the charcoal had no better effectin removing the bad flavour and odour ; but clearedit in four months.

Two drachms cleared the spirit in one month.

Four drachms removed the smell in a very sensibledegree, and the spirit became clear in one month.

One ounce of the charcoal completely freed thespirit from the bad smell, and clarified it in afortnight.

An ounce and a half cleared it in eight days; threeounces in five days; four ounces in twenty-four hours;and five ounces in two hours.

The charcoal, mixed with water and distilled,yields an additional quantity of alcohol, but veryimpure, because at the heat required for the distilla-tion part of the absorbed fusel oil is likewise partedwith. The charcoal is said to be the more active thesofter it is. For purifying brandy Stickel prefersbone charcoal to wood charcoal.

Kunkel was the first chemist who made the essen-tial oils contained in spirit the object of research.His method of rectification was to dilute largely withwater and distil. The fusel oil being less volatile,passes over towards the end of the distillation, andyields, when nearly all the alcohol has passed over,a turbid distillate, because the alcohol which distilsover at that stage of the process contains too muchwater to hold the fusel oil in solution. The headand condensing worm must be cleaned after eachdistillation, or otherwise the alcohol which passesover at the beginning of the following distillationwill be strongly contaminated by the fusel oil de-posited in them.

Wood-ashes had for a long time been almost ingeneral use in the rectification of spirituous liquors ;their beneficial effects are due to the amount ofalkali they contain, which enters into combinationwith the small quantity of acid formed in the spirit,as well as with the oily matters.

It would appear that filtration through hydrate oflime has the effect of removing some of the essentialoils from spirit; the practice had been followed inFrance , particularly with those who carried on anillicit trade by adding an odoriferous oil to theirbrandies, and then entering them at the customs asperfumes.

The fragrant principle was removed, subsequently,by diluting with water, and filtering through lime,slaked in the air, which had the effect of separatingthe oil, provided it had not been present in greatexcess.

Zeize affirms that agitation with a small quantityof hypochlorite of lime (bleaching powder) has theeffect of destroying the essential oil, and that the spirit,after distillation from the lime compound, resembles