§ 141. Benzoline (mineral naphtha, petroleum naphtha, petroleum spirit, petroleum ether) is a mixture of the lighter series of hydro-carbons; the greater part consists of heptane, and there is also a considerable quantity of pentane (C7H16) present. The specific gravity varies from ·69 to ·74. It is very inflammable, and is used in sponge lamps, and also as a solvent for gutta-percha, naphthalene, paraffin, wax, and many other bodies. By the practical chemist it is much employed.
The similarity of the terms benzoline and benzene has caused benzoline to be often confused with benzol or benzene, the leading constituent of coal-tar naphtha (C6H6). Mr Allen[132] gives in the following table a summary of the chief points of distinction, both between petroleum naphtha, shale naphtha, and coal-tar naphtha. The table is founded upon the examination of particular samples, and commercial samples may present a few minor deviations.
[132] Commercial Organic Analysis, vol. ii. p. 31.
TABLE OF THE VARIETIES OF NAPHTHA.
| Petroleum Naphtha. | Shale Naphtha. | Coal-tar Naphtha. |
|---|---|---|
| Contains at least 75 per cent. of heptane, C7H16, and other hydrocarbons of the marsh gas or paraffin series; the remainder apparently olefins, CnH2n, with distinct traces of benzene and its homologues. | Contains at least 60 to 70 per cent. of heptylene, C7H14, and other hydrocarbons of the olefin series; the remainder paraffins. No trace of benzene or its homologues. | Consists almost wholly of benzene, C6H6, and other homologous hydrocarbons, with a small percentage of light hydrocarbons in some samples. |
| Specific gravity at 15°, ·600. | Specific gravity at 15°, ·718. | Specific gravity ·876. |
| Distils between 65° and 100°. | Distils between 65° and 100°. | Distils between 80° and 120°. |
| Dissolves coal-tar pitch, but slightly; liquid, but little coloured even after prolonged contact. | Behaves similarly to petroleum naphtha with regard to the solution of pitch. | Readily dissolves pitch, forming a deep brown solution. |
| On shaking three measures of the sample with one measure of fused crystals of absolute carbolic acid, no solution. Liquids not miscible. | When treated with fused carbolic acid crystals, the liquids mix perfectly. | The liquids form a homogeneous mixture when treated with fused carbolic acid crystals. |
| Combines with 10 per cent. of its weight of bromine in the cold. | Combines with upwards of 90 per cent. of its weight of bromine. | Combines slowly with 30-40 per cent. of its weight of bromine. |
§ 142. Paraffin Oil (or kerosine, mineral oil, photogen, &c.) is the chief product resulting from the distillation of American petroleum—the usual specific gravity is about ·802—it is a mixture of hydrocarbons of the paraffin series. It should be free from the more volatile constituents, and hence should not take fire when a flame is applied near the surface of the cold liquid.
§ 143. Effects of Petroleum.—Since we have here to deal with a commercial substance of such different degrees of purity, and various samples of which are composed of such various proportions of different hydrocarbons, its action can only be stated in very general terms. Eulenberg[133] has experimented with the lighter products obtained from the distillation of Canadian petroleum. This contained sulphur products, and was extremely poisonous, the vapour killing a rabbit in a short time, with previous insensibility and convulsions. The autopsy showed a thin extravasation of blood on the surface of each of the bulbi, much coagulated blood in the heart, congested lungs, and a bloody mucus covering the tracheal mucous membrane. An experiment made on a cat with the lighter petroleum (which had no excess of sulphur) in the state of vapour, showed that it was an anæsthetic, the anæsthesia being accompanied by convulsions, which towards the end were tetanic and violent. The evaporation of 1·5 grm. in a close chamber killed the animal in three hours. The lungs were found congested, but little else was remarkable. Much petroleum vapour is breathed in certain factories, especially those in which petroleum is refined.[134] From this cause there have been rather frequent toxic symptoms among the workmen. Eulenberg[135] describes the symptoms as follows:—A person, after breathing an overdose of the vapour, becomes very pale, the lips are livid, the respiration slow, the heart’s action weak and scarcely to be felt. If he does not immediately go into the open air away from the poisonous vapour, these symptoms may pass on to insensibility, convulsions, and death. It often occasions a condition of the voluntary muscles similar to that induced by drunkenness, and on recovery the patient is troubled by singing in the ears and noises in the head. The smell and taste of the poison may remain for a long time.