Page:Popular Science Monthly Volume 13.djvu/91

Rh pumps before described, enters the apparatus at a and passes out as vapor from the orifice b, after volatilization.



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 experiment 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



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 appreciable volume of liquid oxygen, and in liquefying all the other "permanent" gases.