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Section 6: Sale and Distribution

How is the alcoholic strength of Scotch Whisky measured?

In common with other EC countries, on 1st January, 1980 Britain adopted the system of measurement recommended by the International Organisation of Legal Metrology, a body with most major nations among its members. The OIML system measures alcoholic strength as a percentage of alcohol by volume at a temperature of 20°C. It replaced the Sikes system of measuring the proof strength of spirits, which had been used in Britain for over 160 years .

What was meant by proof spirit?

The Customs and Excise Act of 1952 defined spirits of proof strength as follows:

'Spirits shall be deemed to be at,proof if the volume of the ethyl alcohol contained therein made up to the volume of the spirits with distilled water has a weight equal to that of twelve-thirteenths of a volume of distilled water equal to the volume of the spirits, the volume of each liquid being computed as at fifty-one degrees Fahrenheit'.

In other words. proof spirit meant that the spirit at a temperature of 51°F. weighed exactly twelve- thirteenths of a volume of distilled water equal to the volume of the spirit. It was, in fact. a mixture of spirit and water of a strength of 57.1% of spirit by volume and 42.9% of water.

How was whisky tested for proof strength?

Spirit of proof strength was the technical standard by which strength was measured until 1st January, 1980. Hundreds of years ago, spirit of this strength was proved when whisky and gunpowder were mixed and ignited. If the gunpowder flashed, then there was enough whisky in the mixture to permit ignition. Such whisky was held to have been proved. If the spirit was weaker than this proof strength ignition did not take place.

In the 1740's. the Customs and Excise and the London distillers began to use Clark's hydrometer, an instrument devised to measure spirit strength. A more accurate version by Bartholomew Sikes was universally adopted under the Hydrometer Act,1818, and remained in standard use until 1980.

At what strength is whisky sold (a) at home, (b) for export?

All whisky is retailed at a minimum 40% volume of alcohol for the home market. A strength of 43% volume is often found in export markets.

How does U.S. proof strength compare with British and European strengths?

Some U.S. proofs and their British and European equivalents are:
American		British and

100 deg Proof		50% Alc. vol.
 86 deg Proof		43% Alc. vol.
 80 deg Proof		40% Alc. vol.

What sizes of casks are used for bulk whisky and what are their respective capacities?

			Approximate content
Cask			In litres

Butt			500
Hogshead		250-305
American Barrel		173-191
Quarter			127-159
Octave			45-68

What is the liquid content of the bottles most commonly used for Scotch Whisky sales in the home market?

Bottle			70cl
Half-bottle		35cl
Miniature		 5cl

How soon after it is distilled is whisky usually sold?

The normal practice is for the blender to buy the whisky as soon as it is distilled. It is then kept under bond in warehouses at the distillery to mature until the blender requires it. By law whisky must mature for a minimum of three years. although in practice the minimum age is much greater. After blending, Scotch Whisky is usually returned to cask and left for a further period of several months to allow the constituent whiskies to 'marry'. It is then bottled for sale.

© SWA 1995