Determining the Absolute Density of a Gas. 381 



The coupling b is removed and the vessel g inverted in the 

 copper jacket. The wide tuhulure is now uppermost, the 

 narrow one below. This is attached to d, and the upper one 

 to an air-pump, and distilled air-free water drawn into g 

 through the lower tubulure till it is quite full. The vessel d is 

 now raised, the connexion with the air-pump removed, and 

 when d is so high that water is just welling out of the 

 tubulure this is closed with a short pinched rubber tube. 



Broken ice is now filled in round the volumenometer, and 

 after the lapse of some hours the connexion below with d is 



oner 



^1 



k\\\\\\\\y 



~W 



K^> 



broken and the fine tubulure closed with a little piece of wax. 

 The upper tubulure is now opened, and the level in the 

 tubulure lowered by applying bibulous paper till it sinks to 

 the mark etched upon the glass. It is then closed with rubber 

 tubing as before. The ice being next removed, g is lifted 

 out, dried carefully, and weighed. This done it is replaced 

 Phil. Mag. S. 5. Vol. 30. No. 186. Nov. 1890. 2 D 



