small, regular, hexagonal prisms with very brilliant faces, the optical sign being positive. Beryllium chromite, BeO,Cr2O,, prepared by fusing chromic oxide with beryllia and boric anhydride, is a deep green powder, which polarises strongly under the microscope, and consists of minute crystals of a form identical with that of the variety of cymophane known as alexandrite. It is therefore analogous to the corresponding aluminium compound, the artificial cymophane likewise obtained by Ebelmen. Crystallised niobic anhydride forms small, rhombic prisms with two perpendicular cleavages, h' and g', the angle mm being 140° 50′, and the horizontal parameters 0.355: 1. The form seems to be pseudocubic; the acute positive bisectrix is perpendicular to h', the plane of the axes being p. Tantalic anhydride was obtained in rhombic prisms with the faces g'h' well developed, and the subordinate faces m, g2, g3, g3, the angle mm being about 143°. It follows that niobic and tantalic anhydrides are isomorphous. Crystallised beryllia has the parameters a: h = 1: 16305, the optical sign being positive. In crystallised zinc oxide, the parameters are a: h = 1:1-6034, and the optical sign is likewise positive. It follows that these two oxides are isomorphous, notwithstanding the difference in their specific volumes. Aluminium borate, B2O3,3Al2O3, which Ebelmen analysed but did not describe, crystallises in rhombic needles, the dominant face being m truncated by g' and h'; angle mm = 91° 21'; acute positive bisectrix parallel with the vertical, the plane of the axes being parallel with g'. The compound 3B203,2 FeO3,9MgO, which Ebelmen analysed, forms black, opaque prisms, which have very brilliant faces, and probably belong to the rhombic system. The principal faces are m and h', the angle mm being 90° 32'. An analogous compound containing chromium in place of iron forms a dark brown powder consisting of small prisms, which when examined by polarised light seem to belong to the rhombic system. Ebelmen prepared crystallised tribasic borates, B,O,,3RO, which on his assumption that boric acid is analogous to silicic acid, are analogous to peridote, the oxygen ratio being 1: 1; and likewise crystallised sesquibasic borates, which on the same assumption are analogous to enstatite. The tribasic borates actually obtained were the magnesium, manganese, and cobalt compounds. They are isomorphous, and belong to the rhombic system, the parameters being as follows: ·-- mm = 114° 40′ mm = 114 15 mm = 113 52 The faces m are faces of cleavage, and the acute positive bisectrix is parallel with the vertical, the plane of the axes being g'. The principal indices of refraction for D are respectively 1.6748, 16537, 1.6527. The sesquibasic borates obtained are the magnesium, manganese, : and zinc compounds. They are isomorphous, and belong to the triclinic system, the parameters of the mangauese compound being 1-8373 1: 2012, and xy = 76° 26', az 123° 58', yz 92° 6′, g'h' 75·01, ph' 124° 29', pg' 83° 16'. All have easy nacreous cleavage along p, and a less easy vitreous cleavage along t. The nacreous cleavage is almost always perpendicular to an optical axis. C. H. B. Triclinic Felspars with Twinning Striations on the Brachypinacoid. By S. L. PENFIELD and F. L. SPERRY (Amer. J. Sci., 34, 390—393).—The authors give the results of a careful study, in connection with the chemical composition of the felspars, of the striations due to twinning on coPco exhibited by very many cleavage specimens of plagioclase felspar, in addition to the ordinary striations on the basal plane. These striations on coco have been shown by G. v. Rath (Abstr., 1878, 713) to have resulted from twinning according to the pericline law. The two individuals are united by a plane deviating slightly from the basal plane, passing through the macro-axis, and so inclined that the four plane angles it makes with the prisms co'P and coP' and the pinacoid cops are all equal. This is the so-called rhombic section. Owing to the variations in the axial angles of anorthite felspars, the direction of the rhombic section changes considerably. The direction above the line parallel to the edge OP: copco being regarded as positive, and that below as negative, the direction of the rhombic section in felspars of the albiteanorthite group was found by Tschermak to be as follows: In order to show the relation between the direction of the striations and the chemical composition of the felspars, the authors made analyses of cleavage specimens from six different localities, namely: 1, Branchville, Connecticut; 2, Hitterö, Norway; 3, Haddam, Connecticut; 4, Mineral Hill, Pennsylvania; 5, Danbury, Connecticut; 6, Pierrepont, New York. All the specimens show distinct striations on cops, and all satisfy Tschermak's formula as mixtures of Na2Al2SiO16 and Ca,ALSO16. The analytical results are given on the preceding page. Judging from the above, it will be safe to predict that where the striations on co∞ make an angle of about +12°, the felspar will be a mixture of albite with 5 to 10 per cent. of anorthite. The authors have been unable to find many specimens of felspars more basic than oligoclase exhibiting striation on coco. The analysis of a specimen of labradorite from Labrador gave results in very satisfactory accord, both as regards the direction of the rhombic section and the extinction angle on coPco, with the table given by Tschermak. Although the variation in the angles of plagioclase crystals is considerable, the change in position of the rhombic section from +22° to -18° is so great that the direction of the striations will clearly indicate what position any plagioclase holds in the albite-anorthite series. B. H. B. So-called Indicolite from Harlem. By R. B. RIGGS (Amer. J. Sci., 34, 406).-A peculiarly bright blue mineral found at Harlem, New York, was supposed to be the rare variety of tourmaline known as indicolite. An analysis made by the author showed relations very different from those in tourmaline, the analytical results being as follows:: SiO2. B203. Al2O3. MgO. Na2O. K2O. Ignition. Total. 34.82 4:07 55.30 0.57 1.76 1.04 2.96 100.52 The molecular ratios, deduced from the analysis, are closely expressed by the formula 3H2O, (Na,K)20,10Al2O3,10SiÓ2,B2Oз, a new borosilicate. A microscopic study of this blue mineral shows that the angle of extinction. is very small. The mineral is undoubtedly biaxial with remarkable pleochroism (ultramarine, reddish-violet, colourless). Its structure is subfibrous, so as to render the angle of prismatic cleavage somewhat obscure. It is thus certain that the blue mineral is not indicolite, but in all probability a new borosilicate. B. H. B. Remarkable Crystals of Pyroxene from New York. By G. H. WILLIAMS (Amer. J. Sci., 34, 275-276).-Some yellowish-grey crystals of pyroxene occurring in the crystalline limestone of Orange Co., New York, have a peculiar tabular habit produced by the unusual development of the basal pinacoid. A remarkably fine group of these crystals, in the collection of the Johns Hopkins University, exhibits great singularity of form. It consists of six simple tabular crystals, and of two larger ones, which are at the same time twins and hemimorphic. The largest of these crystals measures 3 by 3 cm. The upper portion shows the usual forms: OP, -P, P, 2P, ∞P, ∞fco, coPcs. Below, however, towards the front, there are only the forms 2P and Poo, indicating that the crystal is hemimorphic in the direction of the vertical axis. The lower back quarter of the crystal is exactly like the lower front quarter, but in a reversed position, so that the lower half of the crystal is a twin. The second crystal is essentially the same as the one just described. B. H. B. Blue Clay from Farmington, Maine. By F. C. ROBINSON (Amer. J. Sci., 34, 407-408).-An analysis of blue clay from Farmington, Maine, gave the following results: SiO2. A1,03. 63.69 17.02 FeO. CaO. NagO. H2O. Total. 99.93 An approximate mechanical analysis gave the following percentages: Coarse sand. Fine sand. Fine clay. Water. 4:05 The sand consisted principally of felspar, with traces of quartz and mica. The clay is used for brickmaking. B. H. B. Meteorite from St. Croix Co., Wisconsin. By D. FISHER (Amer. J. Sci., 34, 381-383).-The mass of meteoric iron described was ploughed up in 1884 on a farm in Hammond Township. It weighed 53 lbs., and measured 8 by 8 inches across the face, with an average thickness of 5 inches. The character of the meteorite renders it probable that its fall did not precede the date of its discovery by many months. An analysis of the meteorite gave the following results: Fe. SiOg. Total. Sp. gr. 7.60-7·70 with traces of carbon, copper, and tin. Troilite is present in nodules 5 to 10 mm. in size. On the application of dilute nitric acid, the Widmanstätten figures quickly appear. These are cubical in arrangement. The meteorite now forms part of the Yale University collection at New Haven. B. H. B. The Rockwood Meteorite. By J. E. WHITFIELD (Amer. J. Sci., 34, 387-390).-This meteorite was found in March, 1887, in a field 8 miles west of Rockwood, Tennessee. Three pieces were found. The smallest measured 4 by 3 by 24 inches, and weighed 3 lbs. 10 oz.; the next measured 7 by 6 by 23 inches, and weighed 5 lbs. 133 oz.; and the largest measured 143 by 10 by 84 inches, and weighed 85 lbs. The mass is very brittle. Cut slices show irregu larly shaped stony fragments, with metallic grains distributed through the mass. An analysis of the metallic portion gave 87.59 per cent. of iron, 12:09 per cent. of nickel, with traces of cobalt and copper, but neither phosphorus nor sulphur. An analysis of the stony portion gave the following results: SiO2. Al2O3. FeO. CaO. MgO. Fe. Ni. CI. P. S. Total. 41.92 9-27 22.94 9:09 8.76 3.75 1.74 0.18 0.65 1.58 99.88 This meteorite appears to be a lithosiderite poor in metal, the metallic portion not exceeding 16 per cent. of the mass. The stony part is probably anorthite and enstatite. B. H. B. The Powder Mill Creek Meteorite. By G. F. KUNZ (Amer. J. Sci., 34, 476-477).-This meteorite is identical with the Rockwood meteorite (see preceding Abstract), and has been called from the Powder Mill Creek, because it fell in Cumberland Co.; Roane Co. in which Rockwood is situated being adjacent to this. The author is the possessor of a piece weighing 2000 grams. It resembles very closely the Hainholz, Westphalia, and the Taney Co., Missouri, meteorites. Its sp. gr. is 4745. Chloride of iron (lawrencite) is present in considerable quantities. Under the microscope, clear crystals of anorthite and olivine were seen in the ground-mass of metallic iron. B. H. B. Some American Meteorites. By G. F. Kunz (Amer. J. Sci., 34, 467-477).—1. The Taney Co., Missouri, Meteorite. This is supposed to have fallen in 1857 at a spot near Miney in Taney Co., 11 miles south-east of Forsyth. It was taken 60 miles to a farm in Limestone Valley, Arkansas, on the supposition that it was of value. In June, 1887, it came into the author's possession. It measures 34 by 35 by 29 cm. Its weight is 89-796 kilos. It is similar to the Hainholz, Westphalia, iron, and belongs to the logronite group of Meunier and the syssidères of Daubrée. Two large crystals of olivine are present, and at one corner of the mass there is a large inclosure of augite. The surface of the meteorite is deeply pitted, and exhibits traces of a black crust. An analysis of the metallic portion gave Fe. 89.41 Ni. 10.41 Co. 0.29 P. 0.16 Total. 100-27 The analysis of the stony portion gave SiO2. Al2O3. FeO. CaO. MgO. Nis. FeS. Total. Further analyses of the finely ground stony portion show that the insoluble portion is enstatite only, and that the soluble portion is a lime-iron silicate containing 17 per cent. of alumina. The fragments described by C. U. Shepard (Amer. J. Sci., 30, 1860, 205) as the Forsyth iron, and by J. L. Smith (ibid., 40, 1865, 213) as the Newton Co., Arkansas, meteorite, are undoubtedly parts of the same meteorite which originally fell near Miney, in Taney Co. 2. The Chattooga Co., Georgia, Meteorite.-This mass was found on March 27th, 1887. In all, 12.5 kilos. were found. It is one of the |