Oil, Consol′idated. Syn. Campticon, Factitious caoutchouc. A substance having most of the properties of india rubber, prepared by oxidising boiled linseed oil, or any other oil that hardens on exposure to the atmosphere. To obtain the solid oil, plates of glass are dipped into linseed oil, the films are then allowed to dry, and the process is repeated again and again until the plates are coated with many layers of perfectly oxidised oil. Instead of plates of glass, extensive surfaces of prepared cloth are employed when the manufacture is carried out on a large scale. The solid oil, having been scraped or peeled off the surfaces, is worked with a small proportion of shell-lac, by means of a mixing machine with hot rollers, until a material singularly like caoutchouc is produced. The consolidated oil can be rolled on to fabrics, so as to form a waterproof cloth, having the finish and flexibility of rubber-cloth. By the action of heat the consolidated oil may be converted into a hard substance resembling vulcanite and ebonite. Its useful applications appear to be very numerous, but its manufacture has not as yet made much progress.
OIL-GAS. A mixture of several gaseous hydrocarbons, obtained by passing common whale fat, resin, the heavy petroleum or shale oil, or the tarry residues left after the distillation of these two latter substances, or other cheap animal oil, through red-hot tubes, or by allowing it to fall in drops on red-hot stones or bricks arranged in an iron retort, or other suitable apparatus. The gas has great illuminating power, requires no purification, and is quite free from the ammoniacal and sulphur compounds which vitiate coal-gas. The sp. gr. of oil-gas varies with the heat employed in its production. It averages from 0·76 to 0·90, but it may rise as high as 1·1.
The composition of coal gas, as given by Payen, is as follows:—
| Oil Gas. | Gas from Petroleum residues. | |
| Olefiant gas and homologues | 22·5 | 17·4 |
| Marsh gas | 50·3 | 58·3 |
| Hydrogen | 7·7 | 24·3 |
| Carbonic oxide | 15·5 | — |
| Nitrogen | 4·0 | — |
OILS (Drying). All the fixed oils have an attraction more or less powerful for oxygen, and, by exposure to the air, they either become
hard and resinous, or they only thicken slightly, and become sour and rancid. Those which exhibit the first property in a marked degree, as the oils of linseed, poppy, rape, and walnut, are called ‘drying oils,’ and are used as vehicles for colours in painting. The others are frequently termed ‘glutinous’ or ‘non-drying oils.’
The resinifying or drying property of oils is greatly increased by boiling them, either alone or along with some litharge, sugar of lead, or white vitriol, when the product forms the ‘boiled oil’ or ‘drying oil’ (oleum desiccativum) of commerce. The efficacy of the process, according to Liebig, depends on the elimination of substances which impede the oxidation of the oil. The following formulæ are adopted for this purpose:—
1. Linseed oil, 1 gall.; powdered litharge, 3⁄4 lb.; simmer, with frequent stirring, until a pellicle begins to form; remove the scum, and when it has become cold and has settled decant the clear portion. Dark coloured; used by house-painters.
2. Linseed oil and water, of each 1 quart; white vitriol, in powder, 2 oz.; boil to dryness. Paler than the last.
3. Pale linseed or nut oil, 1 pint; litharge or dry sulphate of lead, in fine powder, 2 oz.; mix, agitate frequently for 10 days, then set the bottle in the sun or a warm place to settle, and decant the clear portion. Very pale.