of Edinburgh, Session 1882-83. 
137 
Monday, 2nd April 1883. 
Mr JOHN MUEEAY in the Chair. 
The following Communications were read : — 
1. On some Laboratory Arrangements. By Dr John Gibson. 
Improved Method of Filtration by Diminished Pressure. 
This apparatus will be best understood by a reference to the figures. 
The bell-jar A (fig. 1) rests, during filtration, on a square block of 
hard wood c, 25 cm. square by 25 mm. thick, over which is laid 
a sheet of vulcanised rubber d of good quality, and not less than 
3 mm. thick. In the centre is a circular disk e also of hard w^ood, 
13 cm. in diameter and about 20 mm. thick, which is held in 
position by four strong brass screws which pass down through the 
rubber into the square block below. In order to prevent air 
