. American chemical journal . raphy of Oxynitrohydrothymine By W. E. Ford. The pyrimidine crystallizes in the triclinic system, show-ing a combination of b (010), c (001), a (100), M (no), d (034)and X (in). The crystals were small, averaging about 2mm. broad by i mm. thick. In habit they present the appear-ance of diamond-shaped tables with beveled edges, as is illus-trated in the figure. The face, h (010), is always the mostprominent, while the prism with the pinacoid, a, and the basewith the dome, d, form the beveling faces. Frequently oneof these latter faces is much subordinated in size,
. American chemical journal . raphy of Oxynitrohydrothymine By W. E. Ford. The pyrimidine crystallizes in the triclinic system, show-ing a combination of b (010), c (001), a (100), M (no), d (034)and X (in). The crystals were small, averaging about 2mm. broad by i mm. thick. In habit they present the appear-ance of diamond-shaped tables with beveled edges, as is illus-trated in the figure. The face, h (010), is always the mostprominent, while the prism with the pinacoid, a, and the basewith the dome, d, form the beveling faces. Frequently oneof these latter faces is much subordinated in size, or may beentirely wanting. The negative pyramid, X, is always small,and often not present. The crystal faces, although distinctto the eye, were very poorly adapted for measurement with 32 Johnson. the reflection goniometer. They were usually quite rough orcurved and gave indistinct and broad signals on the goniom-eter. A series of the crystals was measured on the two-circle goniometer, and the average of the best readings ob-. tained was taken for the fundamental angles, but the anglesas given and the crystallographic constants calculated fromthem can be considered only as proximate. The measuredangles were as follows: (gig) : (iig) = 63°54. (oio) : (igg) = 96°i5- (oio) : (ooi) = 73°38. Zone (oio) . (no) : Zone (gig) . (ggi) = 79°35- Zone (gig) . (iig) : Zone (gig) . (igi) = 5o°5. (gig) : (034) = 7i°33; calc. = li°A^- Using the first five measurements as fundamentals, thecrystal constants were calculated to be a: b: c = : . ar = 8g°59- io7°35, |5 = iGO°25 The crystals show a good cleavage parallel to c (ggi). Onaccount of the nature of the material only a few of the opticalfacts concerning the compound could be determined. Itpossesses a strong double refraction. The extinction direc-tion on b (010) is inclined to the edge between b and a at 31°.The crystals, when looked at in the polariscope in a direction Researches on Pyrimidines. 33 perpendicular to
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