“Cresotinic acid,” a mixture of impure acids obtained from cresols in the same way as salicylic acid is manufactured from pure phenol, was introduced as a bate and unhairing and deliming agent by J. Hauff, of Feuerbach.[91] He also claims the use of hydrochloric acid to liberate the acid after it has been combined with lime in the deliming process. It is only soluble to the extent of about 1 in 800 of water, so that, even if used in excess, no dangerously strong solution is formed, but it has a tendency to slightly swell, and somewhat harden, the hides or skins, so that it is perhaps more suitable for sole than dressing leather. It has also powerful disinfectant properties (see p. 29).[92] [91] Eng. Pat. 14,889, 1888. [92] Compare also Journ. Soc. Chem. Ind., 1889, p. 954. Hauff states that a solution of 18 lb. of cresotinic acid in 500 gallons of water at 30° C. will bate one lot of 50 heavy hides, and that the same liquor may be used continuously, by adding 4-5 lb. more cresotinic acid for each successive 50 hides. For bating glove-leather, Hauff recommends the use of 5 kilos. cresotinic acid dissolved in 1000 liters of warm water for every 500 kilos. of wet skins, to which is added ammonia nearly sufficient to neutralise the cresotinic acid, leaving the solution still slightly acid to litmus paper; and he also advises the addition of 5 kilos. of ammonium chloride or sulphate. The goods are paddled in this solution for about half an hour. “Oxynaphthoic acid,” the corresponding mixed acids of the naphthols (p. 30), has also been patented by Hauff as a bate, since cresotinic acid sometimes acts too powerfully on light skins.[93] He mentions that mixtures of this and cresotinic acid, or salicylic acid, may also be used. Oxynaphthoic acid requires for its solution 20,000 to 30,000 parts of water. [93] Eng. Pats. 10,110 and 12,521. Journ. Soc. Chem. Ind., 1889, pp. 124, 809; 1890, p. 85. A mixture of the α and β mono- and di-sulphonic acids of naphthalene has also been patented for bating,[94] under the name of “Acrilene bating and puering acid.” 150 calf-skins, weighing 880 lb., were pured in a 3 per cent. solution of the α acid, and gave 266 lb. of leather as against 255 lb. from a lot of similar weight treated with hen-dung, and this gain was more than maintained on stuffing, while the shoulders were plumper and fuller. This patent appears to anticipate a part of Hauff’s claim mentioned in the next paragraph. [94] Burns and Hull, Eng. Pat. 8096, 1891; Journ. Soc. Chem. Ind., 1892, p. 48.