ALCOHOL. The liquor procured by distillation of vegetable infusions of a saccharine nature, and juices which have passed through the vinous fermentation. Ordinary alcohol is not pure, containing usually half its weight of water, from which it may be freed by redistillation at a gentle steam or water-bath heat, until its specific gravity it •830. To free it per fectly, it is necessary to add into the still, or retort, caustic lime, calcined pearl ashes, or fused chloride ealcium ; it is then perfectly free from Water, and has a specific gravity,of •793 ; it then boils at 169° Fahr. Alcohol may also be concen trated by eXpOsing it in ox bladdera, OW ing to 'the property which the possess, of allowing Water to pass throtigh the pores and evaporate out, but giv ing little or no facility for the vapor of alcohol to escape. Both surfaces of the bladder should be soaked in wa ter, and freed from fat and minute ves sels adhering on both the outer and inner surfaces ; it then should get a couple of coats of a solution of isin glass on the outer, and double the number on the inside surface ; the spirit is then poured in, but the bladder not quite filled by it, a portion of air occupying the top : it is then tied tightly at the mouth, and hung in a warm place near a stove or oven.
In this way alcohol may be concentrated in twelve hours, and this kind is well adapted for varnishes. Alcohol has a great attraction for water, and if left ex posed, tepidly attracts moisture from the air : it should therefore be kept in well closed vessels. From this property it is well adapted for preserving anatomical specimens. It has the property of dis solving many substances, as soap, cam phor, resins, essential oils, castor oil, forining varnishes, essences, perfumes, and extracts. If these solutions be mixed with water, milkiness or opacity is pro duced, owing to the alcohol separating these substances, by preferring to unite with the water. 'The strength of alcohol is determined by instruments which read off its specific gravity, calculated tables for 'which may be found in more techni cal works. The instruments are termed aleoholmeters, hydrometers. Gay-Lus sae's instrument, the " alcoometre," is probably the instrument yielding the most correct results : absolute alcohol consists chemically of 4 atoms of carbon, 6 of hydrogen, and 2 of oxygen.
ALE. Infusion of barley and infusion of hops, fermented together.