BfINERALOGICAL CHEMISTRY. M i n e r a l o g i c a1 C h e m i s t r 9. 49 Dimorphous Minerals. By C. DOELTER (Jahrb. f. Nii'n., 1894, ii, Mem., 265477) .-The phenomenou of polymorphism, notwitb- standing numerous theories, is not yet definitely elucidated. 0. Lehmann, Mallard, and others have recently assumed that if two substances exhibit different crystalline forms they must also be chemically different. With diamond and graphite, P. Groth also classes aqdalusite and disthene among the chemically dimorphous substances. With a riew to thoroughly investigate the matter, the author has submitted a number of dimorphous modifications, under conditions as nearly as possible similar, to the action of various agents, such as chlorine, hydrogen chloride, hydrogen fluoride, &c. The following minerals were treated.(1) Andalusite and cyanite, (2) ortlioclase and microcline, (3) epidote and zoisite, (4) enstatite and anthophyllite, (5) diopside and actinolite, ( 6 ) iron pyrites and mar- casite, (7) zinc-blende and wnrtzite. With marcasite and iron pyrites, the solubility in water and in sodium sulphide is identical, but the action of soda is quantitatively different. With zinc-blende and wurtzite, the differences are slight. VOL. LXVSII ii. 550 ABSTRACTS OF CHEMIOAL PAPERS. From the fact that on treatment with water and sodium sulphide new substances are formed which are identical with the modification employed in the experiment, the conclusion is arrived a t that, chemical difference of the dimorphous modifications of ZnS and of FeS2 also exist in the solutions of the two, as the conditions of tem- perature were the same in the experiments.Marcasite is notably less decomposed by soda solution than pyrites is. Cyanite and andalusite exhibit but slight differences in behaviour when treated with decomposing agents. With enstatite and bronzite, chemical differences probably exist. In the case of actinolite and diopside, no safe conclusion can be drawn on account of the varying proportions of magnesium and calcium. Natural Oxides of Manganese. By A. GORGEIT (,Tuh?-b. f. Hin., 1894, ii, Ref., 404-406; from Bull. Soc. fran. min., 1893, 16, 96-104, 133--148).-The author has published a further instalment of the description of his investigation on manganese oxides (compare Abstr., 1890, 570; 1891, 270; 1894, ii, 19 and 99).Analyses are given of pyrolusite from various localities, of manganitc from Ilfeld, of hausmamite from Ilmenau, and of braunite from S. Marcel and from Schwarzenburg. B. H. B. , Chromite in Lower Silesia. By H. TRAURE (Jah7.b. f. Min., 1894, ii, Ref., 411-414 ; from Zeit. deutsch. geol. Ges., 1894, 50-67). --Chromite occurs i n small quantities widely distributed throughout the serpentine of the Zobten Mountains. Recently a workable deposit has been found a t the Schwarzenburg, near Tampadel. The chromite has a sp. gr. of 4.21, and contains B. H. B. Cr20,. A1203. Fe203. FeO. MnO. MgO. Total. 41-23 24.58 2.28 16.99 0.58 14.77 100.43 It resembles the chromite of Grochau. The associated minerals are fully described. Formation of Magnesite and Dolomite. By F.W. PFAE’E~ (Juhrb. f. Min., 1894, Beilage, 9, 485-507).-The author describes the experiments which he has had in progress for the past three years to obtain dolomite and magnesite artificially. The experi- ments did not differ essentiallyfrom those of v. Marlet (1847), Hoppe- Seyler (18i3), Scheerer (1866), and others. B. H. B. By H. TRAUBE (Jahrb. f. JIin., 1894, Beilage, 9, 475- 479).-The author gives the results of an investigation of the figures produced on etching davyn. The material employed was obtained from Vesuvius, and hydrochloric, hydrofluoric, and nitric acids were used, the latter being found the most suitable. Analysis of carefully- selected material gave the following results. B. H. B. Davyn. SiO,. Also,. CaO. &O. Na20.C1. SO,. COP 33-12 28-60 9-91 11.91 7.22 5.14 2.38 2.88 B. H. B.PHYSIOLOGlCAL CHEXISTRP. 51 Chemical Nature of Staurolite. By C. EAMMELSBERG (JuTtd~ f. Min., 1894, Beilnge, 9,480--484).-In the staurolite of Lisbon, Penfield found dark carbon-bearing inclusions. In that of Mount Campione, the author found enclosed crystals of blue cyanite. From his analysw, Penfield deduced the formula H2R”,R,S&O2,+ The author now bring.3 forward arguments to show why he is unwilling to accept Penfield’s formula. B. H. B. Rocks and Minerals from the Karakoram Himalayas. By T. G. BOXKEY and Miss C. A. RAISIX (Proc. Roy. SOC., 1894, 55, 468- 487).-The authors describe a series of specimens of rocks and minerals collected by W. M. Conway during his journey in the Karakoram Himalayas. The rocks of special interest described me some consisting almost wholly of Iiornblende, specimens of pied- montite schist, and of schist with conspicuous secondary mica. Among the minerals, is an interesting pseudo-jade, a fragment. found on a moraine ; microscopic examination and chemical analysis show that this specimen cannot be referred to nephrite. It appears to be com- posed of a lime-garnet, a potash-jadeite, a mineral of the scapolite group, and a little pyroxene. Water and Sea-bottom Deposits from the Eastern Mediter- ranean. By I(. NATTERER (Nonatsh., 1894, 15, 530-595; compare Abstr., 1893, ii, 216, and 1894, ii, 102).-In this communication, tho author gives furthur particulars of analyses of water and sea-bottom deposits obtained during the voyage of the ship “Pola,” in the Eastern Mediterranean during 1893. B. H. B. G. T. M.