FORMALDEHYDE. — This gaseous compound, discovered by von Hoffman in 1867, is produced when a current of air charged with vapor of methyl-alcohol (wood-alcohol, or refined wood-spirit) is directed upon an incandescent spiral of platinum wire, or spongy platinum. By means of a suitable condensing apparatus a liquid called formol may be obtained, which consists of a solution of formal dehyde-gas in methyl-alcohol.
A watery solution of the gas is the formalin of commerce, which contains 40 per cent. of formaldehyde.
Formaldehyde is also known as for micaldehyde, methyl-aldehyde, and oxy methylene.
Polymeric Modifications.—When for maldehyde is heated or strongly concen trated, it is converted into a white crys talline powder (paraform, or paraformde hyde), which possesses most of the char acteristics of formaldehyde, owing to its gradual reversion to the gaseous state.
When paraform is volatilized it reverts to the gaseous form, but is redeposited as a sublimate in the crystalline form (surgical dressings and bandages are im pregnated with formaldehyde in this way).
When formalin. (watery solution of formaldehyde-gas) is heated in a dish or vessel, formaldehyde is disengaged and, at the same time, paraform crystals are deposited on the interior of the vessel. Paraform, or the polymerized form of formaldehyde, is also known as para formaldehyde, paraformicaldehyde, tri formol, trioxymethylene, and dry for malin, and may be obtained in the form of white, crystalline powder, or molded into pastils.
Physiological Action.—Formaldehyde has an intensely irritating effect on the mucous membrane of the eyes and air passages. Taken internally, in the form
of paraformaldchyde, in doses as high as 90 grains, it produces no untoward effect.
It is excreted by the kidneys. When in jected subcutaneously in dogs, Pilliet observed congestion and degeneration, change in the kidneys, liver, and spleen_ Formaldehyde is a blood-poison. In troduced into the body, it causes excite ment followed by slow asphyxia, and added to the blood outside the body it destroys the corpuscles and produces lisematin. The last body is formed with out any preliminary change of oxy hromoglobin to reduced haemoglobin. Benedicenti (Arch. f. [Anat. u.] Physiol., II. 3, 4, p. 210, '97).
The ingestion of paraform has not as yet been followed by fatal poisoning. Concentrated aqueous solutions in con tact with the skin are somewhat like car bolic acid. The skin becomes rough and whitish; a sharp stinging is felt if the skin is abraded.
Proper treatment in poisoning by for maldehyde consists in the administration of spirit of Mindererus (the official solu tion of the acetate of ammonium). Large draughts of water were also given in a case reported. Editorial (Jour. de Pharm. et de Chir., p. 10, '99).
Therapeutic Uses.—The chief use of formaldehyde so far has been as an anti septic and disinfectant. It has, as such, been highly recommended by Trillat and Roux, of the Pasteur Institute.