For general purposes alcohol is denatured with a mixture of wood naphtha, heavy benzine, and malachite green, in the proportions of 2 litres, 1 litre, and 2 decigrams, respectively, per 100 litres of alcohol at strength higher than 83°. For varnishes, the spirit is denatured with 2 litres of wood naphtha per 100 litres, and at least 4 per cent. of resin or gum-resin. Special processes of denaturing are also allowed, provided that they are such as to give protection against the regeneration of potable alcohol.