LIQUEFACTION OF THE GASES. 



81 



pumps before described, enters the apparatus at a and passes out as 

 vapor from the orifice 5, after volatilization. 



Fig. 3. Section of the Same. 

 , cast-iron shell containing chlorate of potash ; A A', closed iron tube in which the Eras is con- 

 densed ; C, refrigerating cylinder in which liquid carbonic acid is volatilized ; F, wooden 

 case packed with some bad heat-conductor ; D, reservoir holding liquid carbonic acid, sur- 

 rounded by a refrigerating cylinder in which liquid sulphurous acid is volatilized ; H, case 

 packed with a bad heat-conductor; G, gasometer containing gaseous carbonic acid; K, 

 reservoir for liquid sulphurous acid; P, one of the double-action pumps ; A', cock which 

 can be opened so as to give an exit to the liquefied gas which escapes in the direction shown 

 by the arrows. 



With this apparatus, M. Raoul Pictet, on Monday, December 24, 

 1877, in the presence of members of the Physical Society of Geneva, 

 three different times obtained violent jets of vapor which contained 

 globules of liquefied oxygen. On the following Thursday the experi- 

 ment was made for the fourth time. The manometer, which had risen 

 to 560 atmospheres, after a few minutes fell to 505, and there stood for 



Fig. 4. The Retort and the Tube in which the Gas is liquefied. 



over half an hour, showing by this diminution of pressure the transition 

 of a portion of the gas into the liquid state, under the influence of the 

 140 temperature to which it was subjected. The cock closing the 

 orifice of the tube was then opened, and a jet of oxygen escaped with 

 extraordinary violence. A beam of electric light, projected on the cone 

 of escapement, enabled the spectators to see that the jet consisted of 

 two distinct parts : the one central, a few centimetres in length, whose 

 white color gave evidence of liquid or even solid elements ; the other 

 external, whose blue color showed the return of the compressed and 

 frozen oxygen to the gaseous state. 



In later experiments M. Pictet succeeded in collecting a very appre- 

 ciable volume of liquid oxygen, and in liquefying all the other " per- 

 gases. 



manent " 



VOL. XIII. 6 



