The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Alcohol, Methylated                                      Alcoholometer
Alcohol, Methylated. Rectified spirit to which 10 per cent, of crude wood spirit has been added to render the mixture unpalatable has long been sold, by permission of the Excise authorities, without being subject to the heavy duty payable on alcohol in other forms ; but by a regulation which came into force in 1891 such methylated spirit as is sold retail in the shops must contain, in addition to the 10 per cent, of crude wood spirit,per cent, of petroleum, having a specific gravity of
not less than "800. This petroleum is separated on the addition of water, rendering the liquid milky or turbid ; and methylated spirit containing the petroleum is partially unfitted for several uses to which it was formerly applied in connection with photo-graphy. Methylated spirit of the old kind can be obtained, in quantities of not less than ten gallons, under regulations which can be ascertained by writing to the head of the Excise Depart-ment, Somerset House, London. On making formal application to the Somerset House authorities for a permit to purchase from a distiller ten gallons of methylated spirit free from petroleum, the applicant is waited upon by a local exciseman, and after complying with a number of formalities, more or less detailed according to the degree to which the exciseman is punctilious, the permit is given. (See following article.)
Alcohol, Methylic. An alcohol containing CH2 less than ordinary or ethylic alcohol, and therefore having the formula CH40. It is a chief constituent in the crude wood spirit, used for mixing with ordinary alcohol for the constitution of the methylated spirit of commerce (see Alcohol, Methylated) ; when pure, methylic alcohol has not the characteristic taste and smell of wood spirit, but rather resembles ordinary or ethylic alcohol. Its specific gravity is '8142, and it boils at about 650 C. The purified commercial methylic alcohol, which costs about 2s. per lb., may be used in most cases as a substitute for ordinary alcohol, but the crude wood spirit, costing about 4-?. a gallon, is generally a less desirable material to use, even than the methylated spirit containingper cent, of petroleum.
Alcoholometer. A hydrometer specially graduated so as to give the strength of alcohol at one reading. (See Alcohol ; also Hydrometers and Hydrometry.)