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.

    98/320 (page 78)
    0-06336 gramme KOH per cubic centimetre), and the excess of alkali titrated with dilute hydrochloric acid, of which 37*4 cubic centimetres were equivalent to 50 cubic centimetres of the potash. For this purpose 5*6 cubic centimetres were required, so that the amount of KOH required to decompose the ether was 1-4262 grammes, corresponding to 2*6171 grammes ethyl tartrate, or 100*35 per cent. The specific gravity of the ether was 1*1989 at 20° Cent. The rotation was observed with the Mitscherlich’s instrument:— Observation. L. Temp. a. [«] I. 99-92 millims. 20-0° 9*932 8*291° II. 49*82 ,, 20*3° 4*974 8*328° Mean: [a]D = 8*309°. (a.) Mixtures with Alcohol. Specific gravity of alcohol employed = 0*7962 at 20° Cent. Three solutions were examined in the Mitscherlich, with a jacketed tube 219*90 millimetres long: — No. of Mixture. Tartrate of Ethyl P• Alcohol. 2- 1 d. c. a. [«]b. I. II. III. 77*9774 35*7366 22*3297 22*0226 64*2634 77*6703 1*08373 0*90892 0*86337 84*5064 32*4818 19*2787 16*315° 6*870° 4*174° 8*780° 9*618° 9*846° The specific rotation rises therefore slowly with successive addi- tions of alcohol, the law of variation taking the form of a slight curve departing but little from a straight line. The formula [a] = A + Bq gives— From Mixtures I. and II. A = 8*343 B = + 0*019839 M „ II. „ III. = 8*525 = + 0*017006 „ „ I. ,, III. = 8*358 = + 0*019156 Whence, taking the mean, [u]D = 8*409 + 0*018667 q. Adopting the formula [a] = A + B q + C q2, we get [a] id = 8*271 + 0*024216 q — 0*000050648^. Thus the values for the constant A agree very nearly with the specific rotation of tartrate of ethyl (8*31).