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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    ends with glass plates, and 30 metres in length, with vapour of oil of turpentine, which he found had still the property of pro- ducing a certain amount of deviation in a ray of polarized light. Unluckily, before the observations were completed, the vapour accidentally caught fire, and the apparatus was destroyed. The experiment was next tried by D. Gernez,1 in 1864, who, with the aid of instruments of a superior kind, determined the rotatory powers of various active substances at rising temperatures, and eventually in the gaseous state. The substances thus examined were orange-peel oil ( + ), bitter orange oil ( + ), turpentine oil (—), and camphor ( + ). In each the specific rotation [a], that is, the angle of rotation calculated for equal densities, = 1, and equal lengths of layer = 1 decim. diminished as the temperature increased; and when the same substances were tested in the gaseous state they gave a specific rotation merely reduced in proportion to the temperature to which they had been exposed. The table appended shows the results obtained with oil of turpentine and camphor :— State of Aggregation. Temp. (Cent.) Density Observed Length of compared with Angle of Tube in water, d. Dotation, o. decim., 1. Specific Botation 0] a dTl Oil of Turpentine (left-rotating). [ 11° 0-8712 15-97° 0-5018 Liquid < 98° 0-7996 14-47° 0-50215 ( 154° 0-7505 13-50° 0-50237 Vaporized | 168° 0-003987 5-76° 40-61 36-53 36-04 35-81 35-49 Observed Density of Vapour at 168° Cent. = 4-981 Calculated ,, ,, ,, = 4-700 Camphor (right-rotating). Melted o O 0-812 31-46° 0-5509 Vaporized 220° 0-003843 10-98° 40-63 Observed Density of Vapour at 220° Cent. = 5*369 Calculated ,, ,, ,, = 5-252 It will be seen that the observed densities of the vapours used 1 Gernez : Ann. Scient. cle Vecole norm. sup. 1,1. C