558 SCIENTIFIC RECORD FOR 1884. 



thus obtained \¥ere found to be tetrabedral in habit, with also the 

 planes of the minus tetrahedron, cube, and perhaps the dodecahedron } 

 there is cleavage parallel to the faces of both tetrahdrons. The crystals 

 are clear and transparent, except as rendered black and opaque by in- | 

 elusions of black grains of titanic oxide. The luster is vitreous. The f 

 narduess is about 7, and the specific gravity 2.875. Several careful ■'[ 

 analyses were made which fix in general the composition of the mineral. \ 

 but without entirely establishing its exact formula. It is shown to be .1; 

 a silicate of aluminum, very low in silica, with nearly 11 per cent, of | 

 water assumed to be basic, as it does not go off at 270°C., also 5.6 per 

 cent, fluorine and 3 per cent, chlorine. The mineral is then as remark- ; 

 able in composition as in crys talline form, and deserves further study. 

 [ProG. Colorado Scientifie Soc, vol. i, 124.) 



NECROLOGY OF MINERALOGISTS, 1884. 



Friedrich EJ[.0CKE. — Born May 28, 1847, in Breslau ; died June 17., 

 1884. He was assistant in mineralogy at Heidelberg in 1868-'70 ; in 

 1879 he became " ausserordentlicher Professor" at Freiburg, in Breis- 

 gau ; in 1881 he became "ordentlicher Professor" of mineralogy and 

 petrography at Marburg. The list of his scientific papers includes 17 

 articles, many of them devoted to physical mineralogy 5 his most im- 

 portant contributions are those upon the cause of "optical anomalies" of 

 crystals as due to secondary causes. (See the Keports for 1882, 1883.) 



Johannes Lorenzen. — Born November 23, 1855, in Sender- Jylland ; 

 died May 5, 1884, when on his way from Copenhagen to Greenland. He 

 was curator of the Mineralogical Museum at Copenhagen, and the author 

 of a number of important mineralogical papers. Among his contribu- 

 tions may be mentioned his memoirs on the metallic iron of Greenland, 

 and the minerals occurring in the sodalite-synite of the Tunugdliarfik 

 and Kangerdluarsuk fiords of Southern Greenland. 



QuiNTiNO Sella. — Born at Mosso, in Piedmont, July 17, 1827 ; died 

 March 14, 1884. He was a mathematician and mineralogist of the high- 

 est rank, and at the same time one of the foremost statesmen of United 

 Italy. In the last capacity he served in several distinguished positions, 

 being for many years minister of finance. His scientific contributions 

 were chiefly in crystallography ; he also took an active part in the ar- 

 rangements with reference to the geological survey of Italy. He was 

 president of the R. Accademia dei Lincei. 



BIBLIOGRAPHY OF MINERALOGY; 1884. 

 I. — Mineralogical works. 



Bauerman, Hilary. Text-book of descriptive miueralogy. 399 pp. 12mo. Lon- 

 don, 1884. 



Baumiiauer, H. Kui^(^sLebrbuchderMineralogie. 190 pp. 8vo. Freiburg, Baden. 



BoiTRGEOis, L. Reproduction artificielle des min^raux. 288 pp. 8vo. Paris, 1884. 

 (EncyclopMie Cbimique.) 



