_Oxynaphthoic acid_, α hydroxynaphthoic acid, C₁₀H₆(OH)COOH, which bears the same relation to naphthol as salicylic acid does to phenol, is cheaper than salicylic acid, and said to be a more powerful antiseptic. Its salts have no antiseptic power. In its commercial form it is a reddish crystalline powder, inodorous, but with a burning taste, and its dust causes violent sneezing. It is scarcely soluble in water, and is said to undergo some change on keeping which lessens its germicide power; it is readily soluble in alcohol, and the solution produces a milky fluid on mixture with water. Such a solution containing 15 grams of the acid in 4 liters of water, will sterilise a hide. Eitner recommends[13] that it should be dissolved in dilute soda solution, and the hides, after soaking in it, passed through water slightly acidified with hydrochloric acid, as has been suggested in the case of naphthol; the method is also applicable to creosotinic acid, the hides being permanently sterilised so that they cannot be unhaired by sweating, though they will lime in the usual manner. [13] Gerber, 1888, p. 101; 1889, pp. 99 _et seq._ See also p. 163. _Carbon disulphide._--Moret has suggested an aqueous solution of this compound as an antiseptic, and it seems to have considerable sterilising powers, but from its inflammability, poisonous character, and unpleasant smell, it is not likely to come largely into use. _Formaldehyde_, COH₂, has recently been introduced as an antiseptic in aqueous solution containing 40 per cent. of formaldehyde together with a little formic acid, under the names of “formalin,” “formol,” etc. It seems to have great disinfectant powers, and may possibly be valuable in various processes of leather manufacture as it becomes cheaper, but has a curious hardening tanning effect on hide fibre and gelatinous matters, so that in very dilute solution it will produce leather.[14] The vapour of formaldehyde, or of its condensation-product paraform, may be employed to harden microscopic preparations. 1 part of formaldehyde, and consequently 2¹⁄₂ parts of “formalin” in 12,000 parts of water, is said to sterilise, and this proportion would form a good disinfectant solution. Even in considerably larger proportion than the above, it does not appear to be poisonous, and thus possesses the bactericidal power of sublimate without the latter’s poisonous properties. Formaldehyde has another advantage over most, if not all other antiseptics, in that it may be used as well in the gaseous as in the liquid state, and on that account it is largely employed in the disinfection of rooms or of articles which would be spoiled if they were to be wetted, as the gaseous formaldehyde, though thoroughly disinfecting them, will not injure the colours of materials of the most delicate fabrics. [14] Gerber, 1897, p. 67; ibid., 1899, pp. 101, 205, 218.