_Benzoic acid_, C₆H₅COOH, though not much employed, except in medicine, is a still more powerful disinfectant, and has the advantage of being non-poisonous to human beings. “_Cresotinic acid_,” which is derived from the cresols as salicylic acid is derived from phenol, is more soluble than salicylic acid. It is not very poisonous, and a powerful disinfectant. In a crude form it has been introduced by Hauff, of Feuerbach, for bating or removing lime from hides. This it does very well, though without the softening action of a true bate. It has a tendency to produce a pinkish stain, and in some degree a sort of tanning of the fibre. Its price, moreover, is rather high for extensive technical use. (See also p. 162.) “_Anticalcium_” is a more recent preparation introduced as a bate by the same firm.[12] It is a solution of mixed sulphonic acids derived from cresols, and has considerable disinfectant powers. It removes lime very effectively, but from its acid character somewhat swells the skin. It is used very successfully as a drench for thin skins (p. 163). [12] Gerber, 1895, p. 133. “C.T.” (coal-tar) bate is a grey crystalline pasty mass, with a tarry smell, and is chemically very similar to anticalcium if not identical with it. _Naphthalene sulphonic acid_ has strong antiseptic properties. Its use in bating has been patented by Burns and Cross. (See p. 163.) _Naphthols_, C₁₀H₇(OH).--These bodies, which have the same relation to naphthalene as the phenols to benzene, are powerful antiseptics; and naphthalene itself appears to have antiseptic power, and is occasionally used for denaturising salt. There are two naphthols, varying in the position of the OH group in the molecule, and denominated α and β, of which α naphthol is the more powerful antiseptic and the less poisonous, though β, being cheaper, is the common commercial article. It is said that quantities so small as 0·1-0·4 grams of α naphthol per liter are sufficient to prevent the development of microbes, while of β naphthol about ten times that quantity is required. Naphthols are not very expensive, but their value is diminished by the fact that they are insoluble in water. They are soluble in alkaline solutions, but their compounds with bases are of much lower antiseptic value, and the same is true of their alcoholic solutions; when an alcoholic solution is added to water the naphthol is precipitated, but if an addition of soap or camphor be made to the alcoholic solution, the naphthol remains in a very finely divided condition, if not dissolved. Adopting Eitner’s suggestion with regard to oxynaphthoic acid (see below), hides may no doubt be sterilised by treatment first with an alkaline naphthol solution, and then with a very dilute acid to set the naphthol free. “_Hydronaphthol_,” β tetra-hydro-naphthol, C₁₀H₁₂O, is obtained by the reduction of β naphthol by sodium (Rideal). It seems to be an excellent disinfectant.