Key points are not available for this paper at this time.
The graphical method was used to determine the signs of P(hk0)'s and P(0k/)'s of tetragonal ethylenediamine sulphate.Using the above-mentioned chart, together with the inequality (1), the signs of 21 out of 31 F(hk0)'s and those of 38 out of 57 F(0k/)'s could easily be determined, and it was possible to make at once Fourier projections on (001) and (100).Details of the structure determination will be published later.
Ginneken et al. (1952) studied this question.