Emich filter sticks

Medium-sized crystals that filter easily can best be collected on an Emich filter stick (micro filter rod 91 G 3, diameter of the plate 3-10 mm). This stick is passed through a stopper through which two holes have been bored and which is placed directly in the flask or testtube or the apparatus suggested by Gut and Sedivy (Figure 16a) may be used.80 In the latter the inner tube B can be raised and lowered, so that receivers A of various sizes can be inserted for ease of handling, the Emich stick is attached to the apparatus by a small piece of plastic tubing. 

Another method involves the use of an Emich filter stick fitted through a rubber stopper into a thick-walled suction tube the filtrate is collected in a micro test-tube (Fig. 2.48). The filter stick has a small pad of pure cotton wool above the constriction. 

It is advisable to use only a feeble vacuum when filtering, otherwise solvent may be lost and filters blocked. The Emich stick should be lowered slowly into the solution, so that the crystals collect at the bottom of the testtube and can be well pressed together. After release of the vacuum, the walls of the testtube and the crystals are washed with a few drops of cold solvent, which is then sucked off. Finally the filter stick is lifted carefully out of the tube, and the crystals adhering to its surface are removed by a micro spatula. 

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