252 THE POPULAR SCIENCE MONTHLY. 



quired to produce this result, for the extreme degree of cold it de- 

 manded 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 hydro- 

 carbons. 



THE OIL-SUPPLY OF THE WOKLD.* 



II. 



MANY and varied are the uses to which human ingenuity has al- 

 ready 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. An- 

 other valuable product of petroleum is gasolene — a form of gas most 

 convenient for use in country houses. Then comes precious parafiine, 

 in the form of beautiful wax-light candles, and vaseline, for healing 

 broken skin or bruises. For medical use we have an ansesthetic 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 resid- 

 uum 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, 



* Abridged from " Blackwood's Magazine." 



