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.

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    tures I., II., III., A = 163*17°; whereas from I., IV., VII. we get A — 153*00°, and from IV., V., VIII., A — 141*16°. For a com- plete expression of the curve an equation of different form must be used, such as that calculated by Dr. Vogler, of Aachen, viz :— [a]D= 115*019 - 1*70607 q + ^2140*8 - 108*867 ? + 2*5572^, which affords values comparable with the results of observation as below:— Number of Mixture. M Observed. M Calculated. Difference. I. 10-0845 133-85° 133-92° + 0-07 II. 21-6080 109-53° 109-49° - 0-04 III. 34-1028 94-24° 94-28° + 0-04 IV. 46-5250 86-58° 86-74° + 0-16 y. 65-7146 80-78° S0-56° - 0-22 VI. 82-3027 76-94° 77-08° + 0-14 VII. 83-6644 76-88° 76-84° - 0-04 VIII. 91-0269 75-53° 75-56° + 0-03 For pure nicotine (q = 0), the above formula gives [a]D = 161*29°, instead of the value found = 161*55°; for q = 100, the value of [a] = 74*13°, so that nicotine, when diluted largely with water, has its specific rotation reduced to less than one-half of the original amount. IV. Tartrate of Ethyl (Dextro-rotatory). § 33. To prepare this substance, an alcoholic solution of tartaric acid was heated for some days in a water-bath along with one-tenth its volume of concentrated sulphuric acid. The mixture was then diluted plentifully with water, saturated with barium carbonate, and the filtered liquor agitated with ether. From the ethereal extract the ether was removed by distillation, and the residue in the retort heated to a temperature of 110° to 120° Cent., whilst a current of dry air was led through it so long as any traces of ether, alcohol, or aqueous vapour were observable. In this way was obtained an ethereal liquid of a pale yellow colour and syrupy consistency, which, when heated on a platinum plate, volatilized without leaving any carbonaceous residue. An attempt to distil it in vacuo was frustrated by the violence of the shocks. As a test of its purity, 2*6079 grammes of the substance were boiled with 30 cubic centimetres of potash solution (containing