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.

    73/320 (page 53)
    In tartaric acid, on the contrary, solid as well as in solution (Biot,1 Tuchschmid2) an increase of specific rotation is observed with increase of temperature for all rays of the spectrum, and in solutions of all degrees of concentration, but in unequal amounts. How variable the values obtained may become in this substance is shown by the observations of Krecke8 in the table annexed Temperature. Tartaric Acid in 100 parts by Weight of Solution. 40 per cent. 20 per cent. 10 per cent. 0° [«nD = 5-53° [«]D - 8-66 [«]D = 9-95° 10° 7-49° 9-96° 10-94° 20° 8-32° 11-57° 12-25° CO o o 9-62° 12-49° 13-93° o ■ 0 11-03° 13-65° 15-68° 50° 12-27° 15-01° 17-11° 60° 12-63° 16-18° 18-31° 70° 13-38° 17-16° 19-42° o o oo 14-27° 18-40° 20-72° 90° 15-91° 19-99° 22-22° 100° 17-66° 21-48° 23-79° Among tartrates, Krecke found that neutral sodium and sodium- potassium tartrate showed a slight increase ; tartar emetic, on the contrary, a decrease. Lastly, in malic acid (Pasteur) and nicotine (see § 32) an increase also of specific rotation with increase of temperature has been observed. Hence in all specific rotation data the temperature at which the angle of rotation and the specific gravity (or concentration) of the solutions have been observed should be given. B. Dependence of Specific Rotation on the Nature and Amount of the Solvent. § 23. The first substance of which the specific rotation was deter- mined by Biot4 (1819) was cane-sugar. He found that with tubes of Biot: Mem. de V Acad. 16, 229. 2 Tuchschmid : ut supra. 3 Krecke: Arch. Neerland, 7, 97 (1872). 4 Biot: Mem. deVAcad. 2, 41 (1819), 13, 39 (1832).