In the Belgian process the reduction and distillation are carried out in cylindrical or elliptical retorts of fire-clay, from 3 ft.
The three isomeric cresols are found in the tar obtained in the destructive distillation of coal, beech-wood and pine.
The solubility of naphthalene by various oils has led some engineers to put in naphthalene washers, in which gas is brought into contact with a heavy tar oil or certain fractions distilled from it, the latter being previously mixed with some volatile hydrocarbon to replace in the gas those illuminating vapours which the oil dissolves out; and by fractional distillation of the washing oil the naphthalene and volatile hydrocarbons are afterwards recovered.
On distillation of equal parts of dry potassium acetate and arsenious oxide, a colourless liquid of unbearable smell passes over, which is spontaneously inflammable and excessively poisonous.
It is also found among the distillation products of bituminous coal, lignite, and various shales, and has been detected in fusel oil and crude petroleum.
It is prepared by boiling the needles in a solution of soda to remove the resin, which process loosens the fibre and renders its separation easy; it has some resemblance to coarse wool, and is spun and woven into blankets and garments that are said to be warm and durable; it is also used for stuffing cushions; an essential oil, obtained by a previous distillation of the leaves, has medicinal virtues attributed to it by some German practitioners.
Various arrangements have been proposed and patented for the continuous distillation of petroleum, in which crude oil is supplied to a range of stills as fast as the distillates pass off.
Large quantities of carbonate used to be manufactured from the aqueous residue left in the distillation of beet-root spirit, i.e.
The pyrites is subjected to dry distillation from out of iron or fire-clay tubular retorts at a bright red heat.
The existing refineries were accordingly altered so as to adapt them for the refining of petroleum; but in the manufacture of burning oil from petroleum the small stills which had been in use in the distillation of shale-oil were at first employed.