H. W. Wiley—Automatic Filtering Apparatus. 351 
Neither Mariotte’s bottle nor the Bunsen pump were capable 
of general application 
As a result of a series of experiments the following appa- 
ratus was devised and successfully put into operation. 
An tna filter-stand, with two arms, is fitted with a large 
glass funnel, A, of from one to four liters capacity. The lower 
arm holds a common small Bunsen funnel, B, so placed that 
the axes of the two funnels coincide. D is a small electro- 
magnet attached to the upper arm of the stand. The neck of 
the large funnel should be drawn out until it has an internal 
diameter of eight or nine millimeters. Passing down the cen- 
ter of the large funnel, and fitting into its nec ik is a glass rod, 
a, covered by | a piece of a soft white caoutchoue connector. 
lhe glass rod is about twenty centimeters in ength, and « 
such a size that when covered by the rubber hose it will com- 
pletely close the orifice in the neck of the funnel. 
