One solution, tested in the polarized-light apparatus, turned the plane to the right; the other solution turned it to the left. 李贝.西洋科学史.
With this idea clearly in mind, the theory of the polarized relay, generally called polar relay, as presented in the diagram (Fig. 7), will be readily understood. 弗兰克·刘易斯·戴尔.爱迪生的生平和发明.
Racemic acid, however, which is identical with tartaric acid in i ts chemical constituents, is optically inactive, rotating the plane of polarized light n either to the right nor the left. 李贝.西洋科学史.