Paul D. Cooper 144 Armour Blvd.
A Convenient Micro Filter-Stick
Downsview, Ontario, Canada
The device described here can serve to replace conventional sintered glass filter-sticks. It has the additional advantages of microsize and ease of cleaning. A piece of 7-mm od glass tubing was bent so that one arm could he fitted by means of a rubber stopper to a 25-ml filtering a s k . The end of the other arm was slightly beveled about the inner edge with Carborundum paste. A solid, spherical glass boiling head of about 6 rnm diameter was selected such that almost one-half of it rested within the beveled opening of the tubing. The bead was held in place by a vacuum which was applied a t the other end of the tub'mg. When the beaded end was then immersed in a finely
Volume 4 1 , Number 2, February
1964
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85
divided liquid-solid suspension contained in a 10X 75-mm test tube, only clear liquid was drawn up the filter-stick and into the receiving flask. After the vacuum was released, the solid, which remained packed a b o u t t h e glass bead, was readily dislodged by t a p p i n g t h e beaded end of the filterstick against the inner wall of the test tube. The glass bead was recovered a t a later stage.
