C. (-153 deg.  Fahr.).  M. Wroblewski, of Cracow, who had witnessed some of M. Cailletet’s experiments, and obtained his apparatus, and M. Olzewski, in association with him, also experimented with ethylene, and had the pleasure of recording their first complete success early in April, 1883.  Causing liquid ethylene to boil in an air-pump vacuum at -103 deg.  C., they were able to produce a temperature of -150 deg.  C. (-238 deg.  Fahr.), the lowest that had ever been observed.  Oxygen, having been previously compressed in a glass tube, became a permanent liquid, with a clearly defined meniscus.  It presented itself, like the other liquefied gases, under the form of a transparent and colorless substance, resembling water, but a little less dense.  Its critical point was marked at -113 deg.  C. (-171 deg.  Fahr.), below which the liquid could be formed, but never above it; while it boiled rapidly at -186 deg.  C. (-303 deg.  Fahr.).  A few days afterward, the Polish professors obtained the liquefaction of nitrogen, a more refractory gas, under a pressure of thirty-six atmospheres, at -146 deg.  C. (-231 deg.  Fahr.).  Long, difficult, and expensive operations were required 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 deg.C. (-256 deg.  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 deg.C. (-351 deg.  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.

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EXAMINATION OF FATS.

The methods employed up to the present in examination of fats, animal and vegetable, are mere reactions lacking general application; scattered throughout the literature, and doubtful with regard to reliability, they are of little or no value to the experimenter—­an approximate quantitative examination even of a simple mixture being exceedingly difficult if not impossible, since the qualitative composition of fatty substances