Page:Popular Science Monthly Volume 26.djvu/264

252  to produce this result, for the extreme degree of cold it demanded had to be produced by boiling large quantities of ethylene in a vacuum. M. Cailletet devised a cheaper process, by employing another hydrocarbon that rises from the mud of marshes, and is called formene. It is less easily liquefied than ethylene, but for that very reason can be boiled in the air at a lower temperature, or at -160° C. (-256° Fahr.); and at this temperature nitrogen and oxygen can be liquefied in a bath of formene as readily as sulphurous acid in the common freezing mixture.

MM. Cailletet, Wroblewski, and Olzewski have continued their experiments in liquefaction and acquired increased facility in the handling of liquid ethylene, formene, atmospheric air, oxygen, and nitrogen. M. Olzewski was able to report to the French Academy of Sciences, on the 21st of July, 1884, that by placing liquefied nitrogen in a vacuum he had succeeded in producing a temperature of -213° C. (-351° Fahr.), under which hydrogen was liquefied. Contrary to the suppositions founded on the metallic behavior of this element, that it would present the appearance of a molten metal, like mercury, the liquid had the mobile behavior and the transparency of the hydrocarbons.



ANY and varied are the uses to which human ingenuity has already contrived to turn this precious gift of dirty-green earth-oil. At first its value was only recognized as a lubricating oil for machinery, and a somewhat dangerous burning-oil for illuminating, commonly called kerosene. Now it has been discovered that, by careful refining, all the highly inflammable naphtha, which is the dangerous ingredient, can be separated, and made valuable to painters and chemists, while the oil, thus purified, becomes absolutely safe for domestic use. Another valuable product of petroleum is gasolene—a form of gas most convenient for use in country houses. Then comes precious paraffine, in the form of beautiful wax-light candles, and vaseline, for healing broken skin or bruises. For medical use we have an anæsthetic called rhigolene, and for cleansing we have benzine. Various volatile ethers have been obtained, among others a petroleum-spirit, which acts as a substitute for turpentine, and which will dissolve lacquer. And, after all these good things have been separated, there still remains a residuum of tar, which yields anthracene, benzole, and naphthaline, from which are obtained a madder-red, mauve, magenta, and indigo-blue dyes, which bid fair to supersede those already known to commerce,