Alcohol is an Arabic term used by chemists to signify highly rectified or pure spirit, such as Spirits of Wine; the term has also another meaning, viz., anything reduced into an impalpable powder ; but it is now rarely used in this sense. Alcohol is generally prepared by fermenting saccharine Substances, such as malt, and the process of converting the sugar into alcohol is called vinous fermentation. This process of conversion may be thus briefly described. The liquor containing the dissolved sugar is subjected to a heat of 150° and allowed to cool to 70°, yeast is then added ; very shortly, an internal movement in the fluid takes place, a thick scum forms on the surface, and a gaseous matter escapes, which is carbonic acid gas; the hydrogen in the fluid then unites with a portion of the carbon, and forms olefiant gas, which, uniting with the water (oxygen and hydrogen), composes alcohol, and this, from its superior lightness, passes over and is condensed, in combination with watery vapour, in a cooled receiver. To deprive alcohol of its water, it is passed through dried Carbonate of Potash, Chloride of Calcium, Lime, Barytes, or Alumina; or it may be done by putting it an open vessel under the exhausted receiver of an air pump, previously placed in a vessel containing lime.
Pure alcohol is a transparent, colourless fluid, of a pungent taste and fragrant odour; it is lighter and more volatile than water, burns with a blue flame which becomes yellowish when the spirit is diluted with water, when mixed with an equal bulk of which, it is termed Proof Spirit, it then has a specific gravity of 0 917, and this is not quite so strong as that used for many tinctures and other pharmaceutical purposes, the strength of which is represented by 0930, the gravity of pure alcohol being, according to Lowitz, 0.796, although the Leyden college make it 0815. The pure spirit of commerce is seldom less than from 0.830 to 0.835.
Alcohol is the active principle of all intoxicating drinks, the habitual use of which, according to Dr. Paris, induces "more than half of all our chronic diseases." Brandy, Rum, Gin, Whisky, etc, are but variously flavoured forms of diluted alcohol; medicinally they are sometimes prescribed, and employed with good effect.; brandy has been found especially useful to rouse the system in some cases of extreme debility, and in the sinking stages of typhus fever, etc.
They are sometimes recommended as nervous stimulants in cases of great depression, but there is always danger that the taking of them may become a confirmed habit, which will grow upon the patient, and eventually make a wreck of mind and body.