4. Linseed oil, 100 galls.; calcined white vitriol (‘sulphate of zinc’), in fine powder, 7 lbs.; mix in a clean copper boiler, heat the whole to 285° Fahr., and keep it at that temperature, with constant stirring, for at least one hour; then allow it to cool, in 24 hours decant the clear portion, and in 3 or 4 weeks more rack it for use. Used for varnishes.
5. (Liebig.) Sugar of lead, 1 lb., is dissolved in rain water, 1⁄2 gall.; litharge, in fine powder, 1 lb., is then added, and the mixture is gently simmered until only a whitish sediment remains; levigated litharge, 1 lb., is next diffused through linseed oil, 21⁄2 galls., and the mixture is gradually added to the lead solution, previously diluted with an equal bulk of water; the whole is now stirred together for some hours, with heat, and is, lastly, left to clear itself by exposure in a warm place. The lead solution which subsides from the oil may be used again for the same purpose, by dissolving in it another lb. of litharge, as before.
6. (Wilks.) Into linseed oil, 236 galls., pour oil of vitriol, 6 or 7 lbs., and stir the two together for 3 hours; then add a mixture of fuller’s earth, 6 lbs., and hot lime, 14 lbs., and again stir for 3 hours; next put the whole into a copper, with an equal quantity of water, and boil for about 3 hours, lastly, withdraw the fire, and when the whole is cold, draw off the water, run the oil into any suitable vessel, and let it stand for a few weeks before using it. Patent.
7. (‘Allg. Polytech. Zeitung.’) Binoxide of
manganese (in coarse powder, but not dusty), 1 part; nut or linseed oil, 10 parts; mix, and keep the whole gently heated and frequently stirred for 24 to 36 hours, or until the oil begins to turn reddish. Recommended for zinc paint, but is equally adapted for other purposes for which boiled oil is employed.
Obs. There is often a difficulty in obtaining the oils ‘bright’ after boiling or heating them with the lead solutions; the best way, on the small scale, is either to filter them through coarse woollen filtering paper, or to expose the bottle for some time to the sun or in a warm place. On the large scale, the finer oils of this kind are often filtered through Canton-flannel bags. The litharge and sulphate of lead used in the above processes may be again rendered available for the same purpose, by washing them in hot water, to remove adhering mucilage.
OILS (Empyreumat′ic.) Syn. Olea empyreumatica, L. The ’empyreumatic oils’ of the old pharmaceutical writers were oily fluids obtained by the dry distillation of various substances, animal, vegetable, and mineral. But few of them are in use at the present day, though formulæ are given for them in some of the foreign pharmacopœias. Two or three have useful applications in the arts, and it is therefore necessary that we should briefly describe their preparation. When the ingredients are of a liquid or pasty nature, or become so when heated, they are usually mixed with about twice their weight of sand, powdered glass, or other like substance, to divide them, and thus expose them more effectually to the action of the fire. Care must also be taken to provide a well-cooled receiver, which must be furnished with a tube to carry off the non-condensable gases liberated at the same time as the oil. The products of the first distillation are generally purified by rectification, either alone or along with water. In general, they require to be preserved from the light and air.
The following are the principal substances belonging to this class:—
Oil of Al′oes. Syn. Aloetic oil; Oleum aloeticum, L. 1. From Socotrine or hepatic aloes distilled along with sand.
2. (Batavian—Cadet de Gassincourt.) Olive oil, 1 lb.; hepatic aloes and myrrh, of each in powder, 2 oz.; olibanum, 1⁄2 oz.; distil in a sand bath, from a stoneware retort. Used as an external vermifuge for children; a portion is rubbed 2 or 3 times a day over the umbilical regions.