Use of Felt-Tipped Pens with Recorders We have experienced a number of problems with the pens in certain potentiometric recorders and similar instruments. The height of the ink reservoir had to be carefully adjusted to get the correct flow rate, and even when this was done, the pen sometimes stopped writing when it moved rapidly across the chart paper. In addition, the pen became clogged easily and frequent cleaning was necessary. The problems associated with these pens can be eliminated completely if a felt-tipped pen is used instead of the one supplied with the instrument. To change the pen, simply remove the pen (and reservoir, if desired), put a felt-tipped pen in the pen holder, and secure the pen with a rubber band. Flair@pens are especially useful here since they fit exactly in the pen holder; this may not be true for other brands. Since the ink used in Flairs pens is not waterproof, it may be desirable t o use another ink, such as India ink, with theFlair@pen; if so,the article by Williams should be consulted [see J. CHEM.EDUC.,47,282 (1970)l. JOHN C. RINGEN QUEENSCOLLEGE FLUSHING, NEWYORK11367
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Journal o f Chemical Educafion
