I Aquef action of Gases, 197 



with oxygen or air, and the working of both the larger and 

 smaller pump, must be accomplished not by hand, but by 

 means of a gas-motor of 1-3 H.P. 



The indispensable condition for such experiments to be 

 successful, is the purity of the gases to be liquefied ; the 

 liquid carbon dioxide, used as a frigorific agent, must be free 

 from moisture ; the ethylene, oxygen, and air must be com- 

 pletely dry and free from carbonic acid. A small amount of 

 carbon dioxide in oxygen or air renders these gases turbid 

 and opaque when liquefied : a slight quantity of moisture 

 may freeze and stop up the narrow tubes which join together 

 the component parts of the apparatus, and thus frustrate the 

 experiment, prepared with so much trouble. In order 

 absolutely to purify oxygen and air from water and carbon 

 dioxide, there must be put into the bottle a, before it is 

 charged, 1 kilog. of potassium hydroxide in thin sticks, that 

 will in a few days completely absorb the moisture and carbonic 

 acid which may be produced whilst the gas is being forced 

 into the flask, in consequence of the action of the condensed 

 oxygen on the leather piston of the pump. 



The quantities of liquid oxygen and air I got by means of 

 the apparatus described were quite sufficient for carrying 

 out my experiments on the liquefaction of hydrogen and the 

 examination of the optical properties of liquid oxygen, which 

 I shall shortly describe. On that account 1 did not think it 

 necessary to increase the dimensions of the apparatus (which, 

 however, it would have been easy to do), the more so because, 

 after having liquefied the first 200 cub. centim. of oxygen or 

 air, the operation may be repeated every 15 minutes, on an 

 equal quantity of gas, as long as the store of liquid ethylene 

 suffices, and the pressure in the bottle c does not fall below 

 60 atm. : in this case other cylinders, containing the whole 

 charge of the corresponding gas, should take the places of 

 c and/. 



I now pass to the description of the experiments I have 

 executed by means of the apparatus described, either by 

 myself or working in conjunction w T ith Prof. Witkowski. 



On the Absolution Spectrum and the Colour of 

 Liquefied Oxygen. 



[Notice published in German in the Bulletin International de VAcademie 

 de Cracouie, January 1891, and in Wiedemann's Annalen, 1891, vol. xlii. 

 p. 633.] 



In my earlier investigations * I found four absorption- 

 bands in the spectrum of liquid oxygen, corresponding to the 

 * Wiener Akademie Berichte, xcv. p. 257. 



