ii. 46 ABSTRACTS OF CHEMICAL PAPERS. Mineralogical Chemistry. Crystal Structure of Copper Pyrites determined by X-Rays. CHARLES L. BURDICK and JAMES H. ELLIS ( J . Amer. Chenz. Soc. 1917 39 2518-2525).-The X-ray interference effects obtained with a crystal of copper pyrites (CuFeS,) show that the iron and copper atoms together form a f ace-centred tetragonal lattice the planes perpendicular to the tetragonal axis consisting of alternate layers of copper atoms and iron atoms. The sulphur atoms are located on an exactly similar face-centred lattice the planes of sulphur atoms being situated a t equal distances from the plznes of iron and of copper atoms in each of the three axial directions. The density of copper pyrites calculated from the weights of the atoms and thhe distances between the atom planes is 4.24 whilst the observed densities recorded in the literature lie between 4.1 and 4.3.H. M. D. R. C. WELLS and B. S. BUTLER (1. TVashinqtom Acad. Sci. 1917 7 596-599) .-This mineral. a tungsten sulphide probably WS occurs intimately intermixed with other minerals in a compact ore from the Emma mine in the Little Cottonwood district Salt Lake' Co. Utah. Under the microscope it is seen as feathery flakes resembling graphite in appearance. It is lead-grey and opaque with metallic lustre and soft enough to mark paper. D about 7.4 (calculated from 6'43 of the specimen analysed allowing for impurities). The mineral is uiiattacked by hydrochloric or nitric acid but is decomposed by aqua regia. It is not oxidised by roasting in air. A bulk analysis of the ore gave W. R. Fo. Zn. Mn. Ni. Pb. As. Sb. Cu. Ag. SiO,. H,O. Totd. corresponding with WSo 61.5 ; pyrites 17.3 ; tennantite and tetra- liedrite 8.1 ; galena 4.7%. I n chemical composition and physical characters the mineral is analogous t o molybdenite (MoS,). Tungstenite a New Mineral. 44.7 29.1 8.S 0.4 0.6 0.3 4.1 1.0 0.8 1.3 0.4 0.3 0.7 92.5 L. J. S. The Photographic Spectra of Meteorites. SIR WIL14rAni CROOKES (Phil. Trans. 1917 [ A ] 217 411-430).-See this vol. ii 25.