The sensitivities of the first order sensitive colors are measured with parallel and crossed Nicols. The results are as follows.
(1) The sensitivity with parallel Nicols is about 1.5 times higher than that with crossed Nicols, showing good agreement with calculated values, as predicted by H. Kubota.
(2) Retardations, at which the sensitive colors are given, are 293.7 mμ in parallel Nicols and 584.4 mμ in crossed Nicols, deviating 13.9 mμ and 24.8 mμ to blue side respectively from the calculated values.
(3) The sensitivities of the measurement of retardation by sensitive colors are about 4.2Å with parallel Nicols and about 6.7Å with crossed Nicols.
