COLLECTING GASES FROM WATER AND OTHER LIQUIDS 273 



apparatus the pressure within and without the apparatus is 

 always the same, and the apparatus is at the same time kept 

 constantly full. 



% I 



The flask {e) is fitted on to the glass tube (d) by a strong 

 tube of vulcanised caoutchouc, bound round firmly with wire, 

 so that no escape of water or gas occurs, although used for 

 weeks together. To the other end of the tube (</) is 

 attached a thick balloon of vulcanised caoutchouc (c), it may 

 probably be as well to have it thin, but for the sake of con- 

 venience, this kind being readily found in the shops, I have 

 used it thick. The small tube at the top is, of course, 



2 M 



