On analysis, the crystals we obtained were found to contain C8H8O3. This is exactly the composition which recent researches of Carles have established for the aromatic principle of vanilla. The transformation of the crystalline product of fermentation into vanillin is represented by the following equation:
C10H12O3 + O = C2H4O + C8H8O3.
To remove all doubt regarding the identity of artificial vanillin with the natural compound, we have transformed the former into a series of salts, which have the general formula, C8H7MO3, and into two substitution products, C8H7BrO31, and C8H7TO3, both of which had previously been prepared by Carles from the natural compound.
VAN SWIETEN’S SOLUTION. Contains 1⁄1000th part of its weight of corrosive sublimate; or 1⁄2 gr. per fl. oz.
VAPOUR. Vapours are really gases, and amenable to substantially the same physical laws; as ordinarily understood, however, the difference between a gas and a vapour is the following:—A gas is a form of matter which exists, at ordinary temperatures and pressures, in a state of vapour; whilst a vapour has been formed by the application of heat to a body usually existing in the solid or liquid form; gases, therefore, differ from vapours only in being derived from bodies which, in the solid or liquid form, boil at very much lower temperatures.
Vapour of Ammonia. Syn. Vapor ammoniæ. (St Th. Hosp.) Solution of ammonia (·959), water, equal parts. A teaspoonful in a pint of water at 80° F. for each inhalation. In chronic laryngitis and functional aphonia.
Vapour of Benzoin. Syn. Vapor benzoini. (St Th. Hosp.) Compound tincture of benzoin, 1 oz. A teaspoonful to 1 pint of water at 140° F. In acute inflammation of the pharynx and larynx.
Vapour of Carbolic Acid. Syn. Vapor acidi carbolici. (St Th. Hosp.) Carbolic acid, 420 gr.; water, 1 dr.; 20 drops of this in 1 pint of water, at 140° F., for each inhalation. For syphilitic and carcinomatous ulcerations.
Vapour of Chlorine. Syn. Vapor chlori. (B. P.) Put chlorinated lime, 2 oz., into a suitable apparatus, moisten it with cold water, and let the vapour that arises be inhaled.
Vapour of Conia. Syn. Vapor coniæ. (B. P.) Mix extract of hemlock, 60 gr.; solution of potash, 1 dr.; and distilled water, 9 dr. Put 20 minims of the mixture on a sponge, in a suitable apparatus, that the vapour of hot water passed over it may be inhaled.