spirits

general 

Alcohol, the liquid most of us so willingly enjoy in a form or another. It is the quintessence of many of the world's most celebrated beverages, from wine to pure medical spirit, is manifest most powerfully in "The water of life", aqua vitae or spirits. In these, regardless of flavour or strength, the arts of distillation play a very significant if not total role.

Spirits, which may range from a little over 20% alcohol up to a dangerously high level 99% alcohol, are produced legally or illicitly in near every country around the globe. You can find them in huge variety of bases and flavours, in numerous brands and every imaginable taste and qualities from the superb to the noxious. They have been prescribed and proscribed and above all, taxed.

distillation

To start with, the role and presence of alcohol needs some defining. Wine holds alcohol, some also contain distilled spirits, even though it's widespread custom to talk about alcohol as something separate from the natural vinous product and to reserve the term for distillates.

The word dates from early Arabic civilisation. It derives from al-koh'l, a very fine metallic powder, often antimony, used as a cosmetic. The word became to mean anything highly refined and hence to distillation, which is a form of refinement. The Arabic association was probably reinforced by Islamic alchemists, who used forms of distillation to obtain perfumes from flowers and perhaps making alcohol for medicinal purposes.

Unfortunately there is very little knowledge considering the early history of distilling or precisely who invented the process. Certainly it was being practised before the scientific principles underlying it were understood. The whole concept depends on the fact that alcohol evaporates at a lower temperature than water, 78.3° C.

It may be presumed that even though there was no technical knowledge of temperatures, experimenters in various parts of the world found they could, by heating wine and trapping the vapour, make a stronger beverage, just as they could concentrate and refine perfumed oils from flowers. It is believed that the Chinese were performing some sort of distilling from rice already over 3000 years ago.

By 800 BC the practise had spread to India and Japan. When distillation arrived to Western Europe is under constant debate, there are semi-legendary tales of distilling in Ireland over thousand years ago, and there are claims that the first proper separation of alcohol and water (alcool vini) took place in France around 1100 A.D.

The first real evidence doesn't emerge until 1519, when a fairly effective still was illustrated in Das Buch zu Destillieren by Hieronymous Braunschweig. The distillation in Europe most probably antedates that by many years, but only during the last 400 years has distillation of spirits become a commercial proposition and gradually it has assumed its current importance socially and economically.

Of all known types of alcohol two are the basic: the one that matters is ethyl alcohol (ethanol), and the other main group is methanol (also called wood alcohol) which is a poison.

Two general styles of still are in regular use for predicting potable spirit: the pot-still, also called alambic, and the patent (continuous) still, named after Aeneas Coffey who perfected it.

pot-still

The pot-still has remained practically unaltered for centuries, apart of obvious refinements and with changes in detail for specific products: thus a Scotch whisky still is not exactly the same as that used for cognac. The pot-still is used as well for primitive distillations (moonshine to you and me) as for the best whisky, brandy and special rum. It also plays a part in production of superior gin.

For which ever purpose the pot-still is used, for making moonshine or the finest Highland malt, the principle is essentially the same. In reality, it's a gigantic kettle. Into it goes alcohol bearing liquid and when the right degree of heat is applied the alcohol evaporates. This steam carries only a little water in it, and in which flavourings inherent in the original liquid are suspended —wine or whatever. When the alcohol vapour cools in a condenser it is then spirit.

continuous Still

The continuous still is altogether different. Patented in the 1830s by Aeneas Coffey it was improved from a continuous distillation which was evolved in Scotland, originally developed by Robert Stein who was a major figure in the early Lowland Scotch whisky industry. The continuos still obviates the long delay for refilling which is required in the pot-still method, it is also more complicated equipment than the pot-still.

The benefits of the continuos still enables modern distilleries to have a flexibility of control beyond that of pot-stills and thus allows them constantly produce quantities of high-strength, high-quality alcohol.

Continuos still has its benefits in mass production of basic unflavoured spirits which will eventually become gin or vodka, but is unsuitable for making fine malt whisky or brandy. It is also excellent for production of fairly heavily flavoured spirits, such as rum, and is at its best when lightly flavoured spirits, such as grain whisky, is produced.

However, these two methods are not in rivalry: they tend to complement each other in many directions, or are employed to produce distinctively different styles of spirit. Occasionally, a modified rectifier column, as used in continuos distillation, will work in conjunction with a pot-still: it's function then will be to rectify (purify) completely spirit that is going to be transmuted into, say a fine London Dry gin.

Preparations must be made to all distilling an alcoholic fluid. The most common sources are wine, grain or fermented molasses, though others such as potatoes, fruit and rice can be used as well. During the manufacture of alcoholic washes on the scale of modern industry, a great deal of carbon dioxide is given off. It forms a by product almost as important as the subsequent distillates.

matter of proof

Since the introduction of spirits into the social arena, methods of assaying their strength have been sought. When alcohol came to be taxed, this became a matter of urgency and essential when and where the tax was related to the proportion of alcoholic content. Not until recently the question of protecting consumer was a high priority.

Probably the earliest idea of how to assess what constituted aqua vitae was to dip a rag into the liquid and ignite it. If it contained sufficient alcohol the rag would catch fire, otherwise the liquid would be too watery and naturally not burn.

By the 15th century another method had become popular; that of pouring oil on to the fluid. If the oil sank, the spirit was strong enough; if it stayed on top, it was too weak. These methods gave no other indication but establishing a vague minimum level.

After those two primitive methods mentioned above, the gunpowder treatment was a slight improvement. The liquid was mixed with the explosive, and a flame was applied. If the liquid didn't ignite, it was not strong enough. If it flared, it was sufficiently ardent to be passed as 'proved'.

If it exploded mildly, it was stronger still, or 'over-proof'. Another old process of proving spirit was to burn of the alcohol: if the residual liquid was less than half the original quantity, the spirit content was satisfactory.

taxman takes his share

The first recorded use of taxation according to proof dates over 300-years back, in 1688 to encourage English distilling imported spirits were charged a duty of two shillings per gallon or 'single-proof' and twice that sum for 'double-proof'.

Some very experienced distillers could, and perhaps still can, determine the strength with remarkable accuracy by partly filling a glass jar with spirit and, by striking the base, cause small bubbles to rise to the surface; the larger the bubbles and the longer they last, the stronger the alcoholic content.

scientific methods

Areometer was the first scientific instrument to measure alcoholic strength, it worked on a principle originally discovered by Archimedes. Known as the mustimètre in France, it is used there to test the specific gravity of grape 'must' and thus to forecast the probable strength of the wine to be fermented from it. Broadly with spirits, the greater the specific gravity, the lower their strength.

The English scientist Robert Boyle laid the foundations for the introduction of the first practical hydrometer for measuring the specific gravity of liquids in 1730. However, it took over 30 years before the 'proof' was defined (1762).

It took another 23 years before an improved hydrometer was legally approved in England as an instrument for assessing the strength of spirits. Finally in 1816 a retired Collector of Excise Taxes, Bartholomew Sikes (or Sykes) developed a proof measurement system which remained unchallenged for over 150 years.

Nowadays the strength of alcohol is assessed to the highest degree of accuracy but the methods and scales vary nationally. The American definition of proof spirit: that which 'contains one-half its volume of pure alcohol of a specific gravity of 0.7939 at 60°F' whereas the British proof spirit was '12/13 of an equal volume of water at 51°F'.

gay-lussac system

Probably the most widely employed system today is the French Gay-Lussac system which simply expresses alcoholic content in percentage of pure spirit: a bottle with 45° on it means that the contents have 45% pure alcohol by volume.

american system

Although the definition of American system seems daunting, it is relatively easy to understand. Proof spirit is represented by the figure 100 and pure alcohol by 200, so therefore halving the proof figure on the bottle will give the strength of the spirit in terms of percentage of pure alcohol. The British system, on contrary, has no such easy reference.

british system

In the British system proof spirit was also represented by 100, but the pure (absolute) alcohol was given the figure 175.25, in practise 175. No one probably ever asked the inventor Bartholomew Sikes, the reasons behind this peculiar arrangement, which vastly complicated the use of the admirable hydrometer he perfected.

Luckily for British consumers, since 1980 has conformed with a recommendation of the International Organisation of Legal Metrology, reinforced by EU (then EEC) directive, and adopted assessment and announcement of alcoholic strengths by percentage of volume. In effect the system is the same as Gay-Lussac, with one, solely technical, difference.