158 Intelligence and Miscellaneous Articles. 



the whole mass, at a sufficiently low temperature, is a solid rock of 

 crystallized matter. At the rise of temperature these substances 

 will melt one by one and absorb heat in so doing. — Silliman's 

 American Journal, January 1884. 





ON THE TEMPERATUEE OBTAINED BY OXYGEN IN A STATE OF 



EBULLITION, AND ON THE SOLIDIFICATION OF NITROGEN. BY 



M. S. WROBLEWSKI. 



Of all the gases formerly regarded as permanent, hydrogen alone 

 showed no sign of liquefaction at the temperature of —136° C. 

 Even when this gas is submitted, at the above temperature, to a 

 pressure of 150 atmospheres, and the pressure is then suddenly 

 removed, no mist is formed in the tube containing the gas. Evi- 

 dently, in order to liquefy hydrogen, we must employ a lower 

 temperature than the minimum obtainable by means of liquid 

 ethylene allowed to boil in a vacuum. Of the gases which are 

 more difficult to liquefy than ethylene, and which might be used 

 for the production of a much more intense cold, oxygen appeared 

 to me to be the most serviceable. 



The conditions under which the liquefaction of oxygen takes 

 place being already ascertained by my previous researches, it fol- 

 lows that this gas can, at the present time, be liquefied in consider- 

 able quantities with great ease. Numberless processes and appa- 

 ratus are conceivable which would allow of this liquefaction being 

 effected in such a manner that the commercial production of liquid 

 oxygen, if I may so express myself, is only a question of materia] 

 means at the service of the experimenter. Thus since the begin- 

 ning of October I have used liquid oxygen as a refrigerating agent. 



When liquefied in large quantity and allowed to evaporate briskly 

 by the sudden removal of the pressure, oxygen does not solidify 

 like carbonic acid, but it leaves a crystalline residue on the bottom 

 of the vessel in which it was contained in the liquid state and upon 

 the object to be cooled, plunged in the oxygen. I cannot say 

 whether this residue is composed only of crystals of oxygen or 

 whether it arises from possible impurities, since the oxygen which 

 I use in these experiments is prepared from a mixture of potassium 

 chlorate with manganese peroxide. This residue disappears as the 

 temperature commences to rise. If the object to be cooled is con- 

 tained in a glass tube, the thin layer of this opaque residue is 

 often very troublesome to the observer. 



Another circumstance which renders it very difficult to employ 

 liquid oxygen as a cold-producer, is the necessity of using closed 

 apparatus capable of great resistance. Hitherto I have not been 

 able to obtain oxygen in a stable liquid condition under the pressure 

 of one atmosphere. I have had, in consequence, to place the objects 

 to be cooled in the apparatus, which 1 fill with liquid oxygen, and 

 I can only avail myself of the cold which the boiling oxygen pro- 



