48 ABSTRACTS OF CHEMICAL PAPERS. Mineralogical Chemistry. Optical Activity of Mineral Oils in Clonnexion with the Question of their Origin. EOMAN ZALOZIECKI and IT. KLARFELD (Chem. Zeit. 1907 31 1155-1156 1170-1172. Compare Kraemer and Spilker Abstr. 1900 i 73 333 ; Walden Abstr. 1906 ii 368; Marcusson Abstr. 1907 i 466 ; Neuberg Abstr. 1907 i 577).-As a general rule light-coloured Galician mineral oils are optically inactive whereas the heavy dark-coloured oils are optically active. Of the fractions obtained from the latter oils only those boiling above roughly 200°/12-15 mm. are optically active. Since heavy dark- coloured mineral oils contain a high proportion of asphaltic and resinous substances the conclusion is drawn that the optical activity of these oils is almost entirely due to the preseuce of colophonic and terpene- like hydrocarbons. The authors discuss the several theories which have been advanced to explain the origin of mineral oils and come to the conclusion that mineral oils are derived not only from fats of higher anirnals but also from substances of both animal and vegetable origin which do not readily putrefy such as waxes wax-fats resins gums &c.W. H. G Enstatite- Augite in Diabase from Tasmania. ALFRED OSANN (Centr. illin. 1907 705-71 I).-Analysis I by Dittrich is of a pale- coloured pyroxene isolated from a medium-grained fresh rock (anal. 11) ccmposed only of pyroxene and zoned plagioclase SiO,. TiO,. A1203. Fe,OB. FcO. MnO. MgO. CaO. Na,O. K20. H,O. Total. 1. 51.87 0'21 2'02 3.50 8.98 0-1s 16'26 15.70 0.16 0'09 1 2 0 100-17 11. 52.49 0'62 16.44 2.60 5.30 trace 6'18 11'71 8.06 1.09 1-67 100.06" * Also t i w e 01 P,Oj.PHYSIOLOGICAL CHEMISTRY. 49 The grains of pyroxene consist of an intergrowth of two optical varieties differing in birefringence and in optical orientation (the optic axial plane being pal-allel to the plane of symmetry in one and perpendicular to it in the other). An attempt to separate these two portions for analysis was not successful. I n the low content of calcium and iron and in the peculiar optical characters this pyroxene resembles those of the enstatite-augite series of W. Wahl (Tsch. >fin. JIiit. 1907 26 1). The comparatively large amount of water is probably present as basic hydrogen L. J. M.