"Ribonuclease II. Accuracy of measurement and shrinkage."

Date:
1954-1955
Reference:
PP/CRI/H/1/32
Catalogue details

Licence: In copyright

Credit: "Ribonuclease II. Accuracy of measurement and shrinkage.". Source: Wellcome Collection.

    11/25
    As a rough estimate the,R.Já r S, error/in the dimana ions uf Llie. wet tin. ce^S ree-H-s- is about 0.02° at a 29 of 18°, or about 0.1°/o/j so that these differences are certainly real. Associated with these changes in «ell dimensions there are changes in the intensities of the reflections. For convenience we have again computed, for the h0¿ reflections, A - . ■% as a measure of the percentage error, grouping together intensities with similar values of l/d. In all cases we have found that the temperature factors do not differ significantly. ^ Smoothed values of A plotted against l/d are shown in F i gw-js-e-s- i to; afté-5. Examine first Fig%n»« $, showing the difference between the ter tiary butyl alcohol case and the ethyl alcohol case. Notice that (except near the origin) the value of A increases roughly ling^a^y with l/d, as might be expected if there were minor shifts ih the molecules between one case and the other. Next compare tertiary butyl alcohol with monoacetin, shown in Fig.^^J, Here the biggest values ofAoccur at very low values of l/d. This is due to the difference in the electron densities of the two solvents, that of 50°/° tertiary butyl alcohol being 0.303 and that of 65% monoacetin as high as 0.373 Examination of the low orders shows that in all cases the monoacetin reduces the intensity. (There is even a small solvent effect between the terti-ary butyl and the ethyl U tM . [p alcohol crystal. Density measurements ( Ki n g J Ma-gé&f f, /del maa—a-ftd- Ha r iter, 1-93^ ) show that the former is slightly heavier, and the low orders of the ethyl alcohol are on the average slightly larger than those of ,