The effect of tourmaline on pH controlling is investigated. The hydrog
en ion concentration tremendously decreases for 1 h. The concentration
approaches 10(-7) mol/l at infinite time. On the other hand, the mate
rials intelligence (I-h) has been suggested. If the f(h) value is 50,
we can determine the I-h value [I-h(50)] for tourmaline. The I-h(50) a
nd P-r values are 0.38 and 0.70 for tourmaline.