and the Critical Volumes of Liquids. 211 



sented in the annexed woodcut is more readily and quickly 

 handled , and enables comparatively large quantities of liquid 

 oxygen to be produced. The arrangements will be at once 

 understood on looking at the figure, which is taken from a 

 photograph. The oxygen- or air-reservoir, C, is made of iron ; 



it contains gas compressed for convenience to 150 atmospheres. 

 A is the stopcock for regulating the pressure of the gas in the 

 glass tube F, and D is the pressure-manometer, the fine copper 

 tube which connects the gas-reservoir and the glass tube, F, 

 being shown at I. The air-pump gauge is marked J, the 

 tube leading to the double oscillating Bianchi being attached 

 at H. The glass test-tube G, which contains the liquid ethy- 

 lene, solid carbonic acid, or liquid nitrous oxide, which is to 

 be boiled in vacuo, is placed in the middle of a larger tube. It 

 has holes, shown at E, in the upper part, so that the cool va- 

 pours in their course to the air-pump are forced to pass round 

 the outside of the vessel and help to guard it from external 

 radiation. The lower part of the outer cylinder is covered 

 with pieces of chloride of calcium, shown at K. If a thermo- 

 meter is used and a continuous supply of ethylene maintained, 

 the india-rubber cork through which the tube F passes has 

 two additional apertures for the purpose of inserting the 



P2 



