WHISKY or WHISKEY, a potable alcoholic liquor dis tilled from cereal grains. The term is derived from the Celtic uisque-beatha afterwards contracted to usquebaugh meaning water of life. The distillation of alcoholic beverages from fermented liquors became general throughout the whole of Europe during the 16th and i7th centuries, but, whilst in the southern grape producing countries wine is the liquor which is subjected to dis tillation, various types of grain are used in the north. Itof interest that in all cases, doubtless owing to their stimulating properties, the same significance attaches to the terms generally applied to strong alcoholic liquors, e.g., eau de vie and aqua vitae, and Robert Burns uses these terms synonymously. At first usque bough referred not only to the plain spirit derived from grain but also to compounded beverages prepared by the addition to the spirit of sugar and flavourings such as saffron and nutmeg.
Whiskies are sometimes classified according to their geo graphical origin :—Scotch, Irish and American, but the chief differences are due to the secondary products—higher alcohols, esters, aldehydes, etc.
(2) The fermentation of the wort to produce the wash.
(3) Separation of the spirit from the wash by distillation. The wort is prepared by mixing various grains with malt, the nature and proportion being subject to considerable variation.
In Irish pot-still distilleries malted and unmalted barley, oats, wheat and rye are generally used, whilst for Scotch pot stills malted barley is practically the only material. In the patent still distilleries in both countries, the wort usually consists of maize, barley, rye (malted and unmalted) and oats, the first, which is seldom used in the pot still whiskies, being the principal in gredient.
The malt or mixture of malt and grain is crushed and raised to a suitable temperature with hot water, the diastase of the malt thus converting the starch into sugar. During this process other substances, the exact nature of which is not thoroughly understood, are obtained in solution. From these are derived the secondary constituents already referred to which impart to the various brands their distinctive flavour. The Scotch pot still or malt whiskies fall into four main types. (I) The High land malts produced chiefly in the Speyside or Glenlivet district constitute one of the most popular. They possess a full ethereal flavour which affords evidence of the fact that the malt has been cured over peat fires. (2) The Lowland malts of the south, al though possessed of an excellent full flavour, are not so distinc tive as those produced in the north and approximate more closely in taste and smell to the patent still spirit. (3) Those produced in Islay have a particularly strong flavour, due in part to the "peated" malt, and are used to a considerable extent for blend ing purposes. (4) Those produced in Campbeltown are similar to the Islays but their flavour is more pronounced.
The patent still spirits do not display the great range and va riety of flavour and bouquet observed in spirits of pot still origin.
This is due in part to the fact that the patent stills render pos sible a much higher degree of rectification and also to the employ ment of malt which has not been cured over peat fires.
their most simple form they consist of a vessel in which the wash is boiled and to which is attached a pipe or "still head" to carry the vaporized ingredients of the wash to a condenser whence the distilled liquor falls into a receiver. The heat is supplied di rectly from a fire, or, in the more elaborate types, by means of steam coils or jackets. The neck was originally made long to prevent the boiling wash being mechanically carried over into the receiver by frothing or spraying. In effect it has a certain rectifying action condensing and returning to the retort the ingredients boiling at a higher temperature. This rectification is in many instances increased by the addition of baffle plates in the tube or small condensers so arranged that liquid condensed therein shall be returned to the retort and not passed into the receiver. This is often effected by an additional pipe or "lyne arm" connecting the rectifier with the retort. In Ireland the stills are usually larger than in Scotland, having a capacity up to 20,000 gallons. The method usually adopted, while varying in detail, is more complicated than that followed in Scotland. Three distillations take place. Strong low wines, weak low wines, strong feints and weak feints (see SPIRITS) are collected and the re sultant fraction has a higher strength, 24 to 3o overproof. The still usually known as the "patent still" was originally devised by Aeneas Coffey in 1831. (See SPIRITS.) It consists es sentially of two columns, the "rectifier" and the "analyser." Each column is subdivided horizontally into a series of chambers by means of per forated copper plates. The columns are filled with steam passed in at the bottom of the analyser. The wash is pumped from the "still charger" through a pipe which passes from the top of the rectifier to the bottom and then to the analyser, where it is discharged on to the first plate. In its course through the rectifier the pipe traverses each chamber twice by means of a double bend. In this way the wash is heated almost to boiling point before it is discharged, the ascending steam and vapours in the rectifier being cooled at the same time by the descending wash. The wash cannot pass through the perforations of the plates in the analyser owing to the pressure of the steam and, by an ingenious de vice of a safety valve and a drop pipe fitted to each plate, an inch of wash accumulates on the plates before any can be discharged to the chamber below. By the continuous upward discharge of steam through the wash the latter is gradually deprived of its alcohol and other volatile constituents which are carried with the steam back to the rectifier where they are condensed. The temperatures of the chambers of the rectifier are suc cessively cooler from bottom to top resulting in a separation of the condensed liquor into various fractions. At one point the temperature is approximately that at which strong ethyl alcohol condenses and the chamber at this point is fitted with a special arrangement for carrying off the liquor condensed therein. In the first and last stages of the distilla tion the spirit collected is not of sufficient strength and is returned to the still, whilst a further device facilitates the collection of the fusel oil, which is of use in commerce. Its value has been enhanced in recent years by the demand for solvents used in cellulose lacquers. Its composition varies considerably.