This consists of a mixture of 9 volumes of ordinary " plain"

1 Cd. 2472, 1905.

spirit and 1 volume of "wood naphtha," to which mixture has been added 0375 per cent. of "mineral" naphtha.1 It contains, therefore, practically 10 per cent. of wood naphtha. (For a description of these two kinds of "naphtha," see later on in this section).

The plain spirit used for methylating purposes must not be of lower strength than 50 over proof. No higher limit of strength is laid down by the regulations. Instead of plain spirit, colonial rum of strength as low as 20 over proof may be used, but in practice rum is now never methylated. Usually the strength of the spirit employed for methylating is more than 60 o.p. No duty is paid on British spirits used for making methylated spirit; and foreign and colonial spirits so used are exempt from the ordinary spirit duty, but pay a small Customs "surtax" of a few pence per gallon. . The idea of this surtax is to compensate for the extra cost of alcohol manufacture in this country due to excise restrictions.

Methylated spirit may only be made by distillers, rectifiers, or licensed methylators. It is, in fact, chiefly made by methylators.

Spirits for methylation come from Customs or Excise duty-free warehouses accompanied by official permits, and are received by revenue officers who examine and check the strength and quantity, and see the spirits run into the mixing vats. To the spirit in each vat is then added one-ninth of its bulk of approved wood naphtha. The contents of the vat have to be thoroughly mixed, the total quantity and strength again measured, and the liquid then further mixed with three-eighths of one per cent. of approved mineral naphtha. The vat and its contents are then handed over to the methylator for disposal in accordance with prescribed regulations. Not less than 500 gallons of methylated spirit must be made at each mixing.

Mineralised methylated spirit is the kind which is ordinarily retailed for burning, domestic, and general purposes. It may not be purified, and it is subject to the general restriction laid down in the Spirits Act, 1880, s. 130 - namely, it may not be employed in making any article capable of use as a beverage, or internally as a medicine. Any quantity up to 5 gallons may be sold by retail at one time, but the seller must be duly licensed for the sale of methylated spirit.

This mineralised spirit is very useful for a large number of purposes, but it has one marked drawback.' It becomes turbid on dilution with water, by reason of the mineral naphtha being thrown out of

1 Since June, 1918, the mineralised spirit has also been coloured with methyl violet solution. This property interferes occasionally with its employment where a diluted spirit is required.

The alcoholic strength of mineralised methylated spirit is usually either about 61° over proof, or about 64° over proof. The general range may be taken as from 60° to 64° o.p., though, exceptionally, spirits as low as 58° or as high as 66° o.p. may be met with. Taking the average strength as 62 o.p., the general composition of the spirit may be expressed as follows: -

Mineralised methylated spirit at 62° over proof.

Note

The sum of the separate percentages is greater than 100, because contraction occurs when water is mixed with alcohol.