A pH Scaler A convenient pocket size scale can be made, by overlaying one cycle of log paper onto a linear graph sheet,' for determining values in the reveror p K t o K . sible calculation of pH to [I%+]; The left two columns show the integral and decimal values of pH. The right fourth column indicates the negative exponent of [I%+], and the log column provides the coefficient. For example, to convert a pH of 6.8 into concentration: From line 6 in the first column look toward the fourth column number which is 7 and indicates lo-'. From 0.8 in the second cohrm, read the Lug scale which gives 1.6, and so the concentration is 1.6 X 10-1. The reverse scaling is then obvious. The figure obtainable from the log scale is, of course, ten times the reciprocal antilogarithm of the decimal portion of the pH (col. 2). 'Kei~ffel& Esser Co., New York, N. Y.; semi-log 464970 and linear 3586. Codex, Inc., Norwood, Illass.; semi-log 32-286 and linear 32Z83R..
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Journal o f Chemical Education
