Proof (unit of measure)

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Proof is an obsolete unit of measure for the alcoholic strength of a drink and is an alternative to expressing it in percentage by volume . While in most European countries the alcohol percentage is given in percentage by volume, this obsolete unit is still occasionally found in the USA and Great Britain .

In the USA, the conversion factor from proof to volume percent is 1/2. Accordingly, the indication of alcoholic strength is in the unit Proof twice the specification in volume. For example, the volume percentage of an alcoholic drink with the specification 101 Proof is 50.5% alcohol. In some countries, e.g. For example, in Great Britain there are other units of measurement such as "Degrees Proof" or "Proof Spirits", especially on whisk (e) ys. "100 Degrees Proof" corresponds to 57.15% Alc./Vol. "100 Degrees Proof" thus corresponds to a conversion factor of 4/7. This means that 100 ° proof corresponds to 50% by volume in the USA and around 57% by volume in the UK. 100 British proofs indicate the value from which gunpowder soaked in the liquid burns with a blue flame. With Overproof a spirit with more than 57% alcohol is known that burns in the same test with a yellow flame, Under Proof is a drink with less than 57% alcohol, which does not burn during the test.

The etymology of the name goes back to the English word proof (= proof, sample). British sailors had tested the strength of the rum they were entitled to by soaking gunpowder with rum and setting it on fire.

State regulations

EU

The EU follows the rules of the International Organization for Legal Metrology . After this, the alcohol content can be given in percent by volume or by mass. No unequivocal recommendation for either method is made. However, it is stipulated that if the alcohol content is stated as a percentage by volume, the alcohol content must be stated as a percentage of the total mass, while the mixture of water and alcohol has a temperature of 20 ° C (68 ° F) at the time of measurement. There are still no regulations regarding bottle labels or the purity of the alcohol.

Great Britain

Since January 1, 1980, the alcohol content in Great Britain has been given in percentages by volume, as required by the EU. On January 1, 1980, Great Britain, together with other EU member states, adopted the recommendations of the International Organization for Legal Metrology. The alcohol content is then measured as a percentage of the volume at a temperature of 20 ° C (68 ° F). This replaces the measurement of alcohol content using the Sike hydrometer, which has been used in Great Britain to determine alcohol content for over 160 years. The measurement procedure of the International Organization for Legal Metrology was adopted by all EU member states in 1980.

United States

In the USA, too, the alcohol content is given as a percentage of the volume. According to Article 27 of the Code of Federal Regulations , manufacturers are instructed to declare the alcohol content of their spirits as a percentage by volume. However, proof is still a common indication for spirits.

See also

Individual evidence

William B. Jensen: The Origin of Alcohol "Proof". Retrieved May 18, 2015 .

Alcohol Problems and Solutions. Retrieved May 18, 2015 .

Meaning of proof in spirits. Retrieved May 18, 2015 .

International Organization of legal Metrology: International Alcoholometric Tables. Retrieved May 18, 2015 .