Handbook of the polariscope and its pracitcal applications / adapted from the German editon of H. Landolt, by D.C. Robb and V.H. Veley.

  • Hans Heinrich Landolt
Date:
1882
Catalogue details

Licence: Public Domain Mark

Credit: Handbook of the polariscope and its pracitcal applications / adapted from the German editon of H. Landolt, by D.C. Robb and V.H. Veley. Source: Wellcome Collection.

    67/320 (page 47)
    § 19. Abnormal Rotatory Dispersion.— Although in ordinary cases the angle of rotation increases pari passu with the refrangibility of the ray, there are exceptions, as Biot,1 and later Arndtsen,3 have noticed in aqueous solutions of dextro-tartaric acid. This acid exhibits, in a remarkable degree, the property that its specific rotation [a] (§ 24) increases with the diluteness of the solution from observation of which it is calculated. The increase is directly proportional to the dilution, and may be expressed by the formula [a] = A + B q, where q represents the percentage by weight of water in the tartaric acid solution. Arndtsen has determined by Broch’s method the devia- tions for the Fraunhofer lines C, D, E, b, F\ e, in a series of solutions of different degrees of concentration, at a temperature of 24° Cent., from which he deduces the subjoined values for the constants A and B in the preceding formula :— A B [«]c H + 2-748 + 0-09446 q [«]d p + 1-950 + 0-13030 q We = + 0-153 + 0-17514 q [a]b = - 0-832 + 0-19147 q [a> k - 3-598 + 0-23977 q [a]e m - 9-657 + 0-31437 q Computing from these formulae the specific rotation for solutions containing from 10 to 90 percent, of tartaric acid, we get the annexed results:— In 100 parts Solution He Red. Wo Yellow. We Green. Wb Green. We Blue-green. We Blue. Water Tartaric Acid. 90 10 11-25° 13-68° 15-92° 16-40° 17-98° (18-64°) 80 20 10-30° 12-37° 14-16° 14-49° (15-59°) 15-49° 70 30 9-36° 11-07° 12-41° 12-57° (13-19°) 12-35° 60 40 8-42° 9-77° 10-66° 10-66° (10-79°) 9-21° 50 50 7-47° 8-47° (8-91°) 8-74° 8-39° 6-06° 40 60 6-53° (7-16°) (7*16°) 6-83° 5-99° 2-92° 30 70 5-58° (5-86°) * 5-41° 4-91° 3-60° -0-23° 20 80 (4-64°) 4-56° 3-66° 3-00° 1-20° -3-37° 10 90 3-69° 3-25° 1-90° 1-08° -1-20° -6-51° 1 Biot: Mem. de VAcad., 15, 93. 2 Arndtsen: Ann. Chim. Phys. [3], 54, 403. Pogg. Ann. 105, 312.