P. Griess (Ber., 1872, 5, p. 192; 18 74, 7, p. 1223) orientated the three diaminobenzenes or phenylene diamines by considering their preparation by the elimination of the carboxyl group in the six diaminobenzoic acids.
In 1869 van Tieghem laid stress on anatomical evidence as a key to the morphology of the cone-scales; he drew attention to the fact that the collateral vascular bundles of the seminiferous scale are inversely orientated as compared with those of the carpellary scale; in the latter the xylem of each bundle is next the upper surface, while in the seminiferous scale the phloem occupies that position.
C. Graebe (Ann., 1869, 149, p. 22) orientated the ortho-compound or phthalic acid from its formation from naphthalene on oxidation; the meta-compound or isophthalic acid is orientated by its production from mesitylene, shown by A.
Ital., 4, p. 305) in 1874 orientated the three dibrombenzenes in a somewhat similar manner.
The more or less rectangular Roman city, orientated on the points of the compass, with its streets arranged at right angles, can be easily distinguished from the outer city, which received its fortifications in 1206 (see G.
Are common and sometimes very puzzling, but they can always be orientated by the aid of the very characteristic striations, on the prism faces, which serve also to distinguish quartz from other minerals of similar appearance.