This is a pale, odorous resin, less hard than lac, with which it is often associated as a spirit-varnish. It consists of three resins differing as to solubility in alcohol, either, and turpentine. It forms a good pale varnish for light-colered woods; when required to be polished, Venice turpentine is added to give it body.

Of the solvents of these various resins, little need be said. In the manufacture of varnishes, great care, as well as cleanliness, are required. The resins should be washed in hot water, to free them from particles of dust and dirt; they should be dried and assorted according to their color, reserving the lightest shades for the best kinds of varnish.

The linseed-oil should be as pale colored, and as well clarified as possible. New oil always contains mucilage, and more or less of foreign matters; as these prevent the regular absorption of oxygen, the oil requires preliminary treatment. The common plan is to boil it with litharge; but such oil varnish is inferior to that prepared with sulphate of lead.

The best method is to rub up linseed-oil with dry sulphate of lead, in sufficient quantity to form a milky mixture. After a week's exposure to the light, and frequent shaking, the mucus deposits with the sulphate of lead, and leaves the oil perfectly clear. The precipitated slime forms a compact membrane over the lead, hardening to such an extent that the clarified oil may be readily poured off.