PARAFFIN, OR COAL OILS.

New Zealander, Volume XVIII, Issue 1719, 30 August 1862, Page 6

PARAFFIN, OR COAL OILS.

Paraffin, or as this fluid is frequently termed, coal oil, has been for some years past largely used as an illuminating agent. The cleanliness and the economy of the paraffin lamps, with the brilliancy of the light produced, have led to their very general adoption, especially in those places where the conveniences of gas have not as yet been made available. Paraffin, and, indeed, all the varieties of the oils which are sold under this name, are, like it, compounds of carbon and hydrogen. They are produced by the distillation, as carefully regulated temperatures, of coal, of certain carbonaceous shales, and the different varieties of petroleum which are now so largely obtained in America and in Asia. As we have said, from whatever source derived, these oils are hydrocarbons, and, according to the temperature at which the distillations effected, there result heavy or light oils, as they are termed by the manufac turers. These oils are of variable specific gravities, and their boilirg points range all the way from 46 ° to 600 ° Fahr. Hence it is that explosions hare arisen from the improper admixture of the lighter oils with the heavier ones. In some coses this has arisen from insufficient purification of the oil for burning, and in others (which include by far the larger number of cases) by the mixtures of volatile oils obtained from other sources w ith the less inflammable oils distilled from coal. In the early stages of this manufacture, Cannel coal j was almost exclusively used as the oil-yielding material, but since the discovery of the oil wells of Pennsylvania and other places, petroleum has in a great measure supplanted the use of coal, some establishments using the natural oil alone. The object of this is readily appreciated. The petroleum being naturally in a liquid state, there is no necessity for a preliminary distillation, as in the case when coal is used, in which event the crude oil must be first produced by exposing the coal to distillation at a low heat, and the resulting product be treated in the same manner as the oil already formed in the wells. By the use of petroleum the retorts for the first distillation are dispensed with, and thus a saving is effected in apparatus as well as in time and labour. When petroleum alone is used in the manufacture of kerosene oil the product contains a much larger proportion of volatile hydrocarbons than when coal w wholly or partially employed, and, therefore, more precautions are necessary, and greater labour is requisite, to effectually get rid of these danger-ous-substances. Some manufacturers not only neglect to remove these volatile compounds from the oils, but actually purchase the light oils from more conscientious refiners, in order to mix them with heavy oils, to make them burn. This is an exceedingly reprehensible practice, and deserving severe punishment, for the heat generated by the heavy oils in burning vapourises the volatile portion, and renders it liable at any time to explode. The oils distilled wholly from coal, or those with which a small proportion of petroleum has been mingled, are much more easily freed from dangerous portions by a careful refining, and after distillation, steaming, and a large surface of atmospheric exposure, every dangerous compound can be removed, and no fear need be apprehended from oils which ate known to be subjected to a rigid and conscientious refining. In purchasing oils, however, nothing should be taken for granted. They should be carefully tested and their liability to explode fully investigated. The simplest and most satisfactory test of safety is to place the oil in an open dish in a water bath, and heat it up to from 130° to 140° Fahr. If when elevated to this temperature, on applying a match it does not ignite, it may be pronounced very safe. If it ignites but slowly or sluggishly it is safe. But any oil that lights quickly in an open dish, at a temperature of below 130° Fahr., may be considered as dangerous. We have seen oij the vapour of which ignited with a smart puff or explosion at 60° Fahr., on holding a lighted match more than one inch above its surface. This was dangerous in the highest degree, and the vendor of such a compound should be held to a strict accountability for any accident occurring from its being burnt in lamps. The extensive use of these oil lamps among the working classes induces us to call especial attention to this very simple test. To those who may not be provided with a thermometer to measure the temperature, the following simple rule may be adopted :—Pour into a basin a pint of boiling, water, and allow it to stand to cool for five minutes, then pour some of the paraffin oil into a teaspoon, and having floated the bulb of the spoon on the hot water, leave it at rest for a few minutes; then hold alighted match a little above the spirit, if it ignites quickly it is dangerous, if not at all, , or very slowly, the paraffin may bo used without fear of accident. A metallic fountain or reservoir should always be avoided in using any of these hydrocarbon oils. To'show the vast difference of the oils now on sale as paraffin oils in this country, Dr. R. Angus Smith, F.K.S., of Manchester, an eminent chemist, has lately found that oil made by Mr. Young, the inventor, and his partners, from coal, and who have really the only right to call their oil paraffin, will not ignite in nn open vessel at 154° Fahr.; while a sample of American rock oil, sold as paraffin, exploded at a temperature of 46 ° ¥eht.—Mining Journal.