very accurate separation of vanadic acid from molybdic acid. The vanadic acid is precipitated as manganese vanadate, the excess of manganese is removed by means of ammonium sulphide, and in the filtrate the molybdenum is precipitated as sulphide by adding hydro chloric acid. In order to separate vanadic acid from its alkaline or ammoniacal solutions, it is precipitated in the form of manganese vanadate, the precipitate is dried and heated with sulphur or in a slow current of hydrogen sulphide, and the residue is treated with hydrochloric acid diluted with 15 to 20 times its volume of water, when manganese sulphide dissolves and vanadium sulphide remains undissolved. C. H. B. Metallic Vanadates. By A. DITTE (Compt. rend., 104, 17051708).-Metallic vanadates are readily obtained in a crystalline condition by adding ammonium vanadate in excess to a solution of the nitrate of the metal, this solution being hot or cold, neutral or acid, as the case may require. Normal magnesium vanadate, MgV2O + 6H2O, is obtained in small, transparent needles by boiling magnesium hydrocarbonate with soluble vanadic anhydride and concentrating the filtered solution in a vacuum. It loses water when heated, becomes yellow, and melts at a higher temperature. If a warm saturated solution of ammonium vanadate is mixed with excess of magnesium chloride, acidified with acetic acid and concentrated in a vacuum, it deposits brilliant red, transparent crystals of the bivanadate, MgO,2V20, + 9H2O. Barium vanadate is obtained in colourless, transparent, anhydrous prisms, insoluble in water, by adding barium nitrate in excess to a boiling solution of ammonium vanadate. In presence of acetic acid, a red solution is obtained and, if this is concentrated, it deposits transparent, orangered, rhombic crystals of the composition 2Ba0,3V20, + 14H2O. Calcium vanadate, CaO,3V20, +12H,O, is obtained in red, lustrous crystals by adding excess of ammonium vanadate to a solution of calcium nitrate containing a very small quantity of free nitric acid. It is very soluble in dilute acids; when heated, it loses water and forms a yellow powder. When calcium chloride is added in excess to ammonium vanadate no precipitate is formed, but on adding ammonia a bulky, white precipitate is produced, and when the liquid is boiled this changes to small, colourless, transparent needles grouped in nodules. It has the composition 2CaO,V2O, + 2H,O, is very soluble in dilute acids, and loses water when heated, forming a yellow powder. Nickel vanadate separates in small, greenish-yellow, anhydrous prisms on boiling a mixture of ammonium vanadate with excess of nickel nitrate feebly acidified with nitric acid. It is very soluble in dilute nitric acid. If the brown-green mother-liquor is concentrated, it deposits greenish-brown, transparent crystals of the composition NiO,2V,0, + 3H2O. Cobalt vanadate, CoV2O. + 3H2O, is obtained in a similar manner; it is very soluble in water, and becomes anhydrous when heated. 2 Zinc vanadate, ZnV2O, + 2H2O, is also obtained in a similar manner in brilliant, pale-yellow, cubic or rhombic crystals which become anhydrous when heated. When a very dilute solution of copper sulphate is mixed with ammonium vanadate, a precipitate is formed which dissolves on heating but becomes permanent if the copper sulphate is in excess. When boiled with the mother-liquor, it is converted into greenish-yellow, transparent, rhombohedral plates of copper vanadate, зCuO,V2O, + 3H2O. Lead vanadate, 2PbÓ, V2O5, is obtained in sulphur-yellow, transparent, anhydrous prisms, terminated by pyramids, by boiling, in the mother-liquor, the precipitate which is formed when ammonium vanadate is added to a solution of lead nitrate acidified with acetic acid. Silver vanadate, 2Ag,O,VO, is obtained in brilliant golden-yellow, transparent, rhomboïdal plates, easily soluble in nitric acid, by dissolving in fused silver nitrate the precipitate produced by mixing solutions of silver nitrate and ammonium vanadate; the fused mass is cooled slowly and is then extracted with water. Silver vanadate dissolves in ammonia, and if the solution is evaporated over sulphuric acid it yields the compound 3AgVO3,2(NH)O in brilliant, yellow, hexagonal needles grouped in mamelons. Cadmium vanadate, CdO,SV,0, + 2H2O, separates in small, brilliant red crystals on boiling the red liquid obtained by adding ammonium vanadate to a solution of cadmium nitrate acidified with acetic acid. These crystalline metallic vanadates are analogous in constitution to the alkaline vanadates. C. H. B. Ammoniacal Vanadates. By A. DITTE (Compt. rend., 104, 1844 -1847).-Methylamine Vanadates.-The normal salt, 2MeNH ̧VO, + H2O, is obtained in colourless, transparent needles by concentrating in a vacuum the strongly alkaline, straw-coloured liquid produced by mixing soluble vanadic anhydride with excess of methylamine. It is very soluble in water, and becomes brown when heated, then almost black, and, finally, takes fire and burns, leaving a residue of vanadic anhydride. The acid salt, (NH,Me),Q,2V2O5 + 4H2O, is obtained in garnet-red rhomboidal prisms on concentrating a solution of the normal salt acidified with acetic acid. It gives a yellow powder which becomes vermilion when heated, and finally takes fire and burns, leaving a residue of the anhydride. Ethylamine treated in a similar manner yields a normal salt, NH,EtVO,, in the form of small, colourless, transparent, deliquescent crystals which on heating decompose with evolution of an inflammable gas, and leave a residue of vanadic anhydride. The acid salt, (NH,Et),0,2V20s, forms transparent, red prisms which burn like tinder when heated. No magnesium ammonium vanadate could be obtained. Magnesium vanadate is decomposed by ammonia with formation of ammonium vanadate and magnesium hydroxide. Ammonium vanadate is only slightly soluble in concentrated ammoniacal solutions of magnesium hydroxide owing to the presence of ammonium chloride. In dilute solutions, no precipitate is formed, and when the liquid is concentrated ammonium vanadate and the double chloride, MgCl2,2NH,Cl, separate. If a solution of ammonium vanadate, strongly acidified with acetic acid, is mixed with a cold dilute solution of potassium silicate, also acidified with acetic acid, and the red solution concentrated, the com pound K,O,2(NH)20,5V2O, + 9H2O is obtained in red transparent prisms. It may be regarded as a molecular compound of the two salts K,0,2V20, and 2(NH,),0,3V20, + 9H2O. When heated, it loses water, blackens, and gives off ammonia, yielding a residue which melts at a red heat. Sodium silicate yields a similar compound which crystallises with 15H2O in brilliant, orange-red plates. Vanadates, whether formed in the dry or wet way, correspond with a few well-defined and simple types, the most important of which are as follows:: Acid Vanadates.-M2O,3V2O; M20,2V2O,; 2M20,3V20. Basic Vanadates.—2M2O,V205; 3M2O,V205; 4M2O,V2O5. The proportion of water which these salts contain depends on the conditions of crystallisation. The more complex salts, 3M,0,5V,Os, may be regarded as compounds of a salt, M2O,2V2Os, with a salt, 2M20,3V20, like the double vanadates just described. C. H. B. Metallurgy of Bismuth. By E. MATTHEY (Proc. Roy. Soc., 42, 89-94). In order to separate gold and silver from bismuth, the author adds 2 per cent. of zinc to the molten metal, allows the mass to cool gradually, and removes the surface crust. This process is repeated. The whole of the gold and silver is found in the skimmings. The bismuth litharge so obtained is fused in a crucible with borax. The gold sinks to the bottom, being at the same time freed from any base metals by the action of the bismuth oxide. The slag is again fused with addition of bismuth to separate the last traces of gold. The author separates bismuth from lead by means of repeated crystallisations, alloys of bismuth and lead melting at lower temperatures than bismuth itself. Bismuth holding 12 per cent. of lead contained only 0-4 per cent. after four crystallisations. H. K. T. Products of the Action of Acids on Alloys of the Platinum Metals. By H. DEBRAY (Compt. rend., 104, 1667-1669).-The presence of a metal of the platinum group in solution in another metal such as tin, lead, or zinc, causes the latter to be much more readily attacked by dilute acids owing to the formation of innumerable minute galvanic couples. Under these conditions, the more oxidisable metal is dissolved by acids so dilute that they would have no action on it under ordinary circumstances. When the platinum metal combines with the other (loc. cit.), this compound forms galvanic couples with the excess of the oxidisable metal. In some cases (for example, the alloys of the platinum metals with tin) the alloy itself is attacked, especially if the acid is somewhat concentrated, and under these conditions some of the platinum metal is dissolved at the same time as the tin, &c. When an alloy of zinc and osmium is treated with hydrochloric acid, or an alloy of lead with iridium or ruthenium is treated with nitric acid, the platinum metal is left undissolved in the form of minute crystals, since it is simply dissolved in the oxidisable metal. When combination has taken place between the metals, with development of heat, as in the case of lead and rhodium, the innumerable galvanic currents which are developed when the regulus is treated with an acid give rise to the formation of a complex residue containing oxygen, nitrogen, and water in addition to rhodium and some lead. Unlike the alloys with tin, this particular alloy gives no definite compound when treated with an acid. The formation of complex residues under the influence of galvanic currents which are due to the heterogeneity of metallic substances which are being dissolved in acids, is analogous to the formation of a silver peroxide or nitroxide when a solution of silver nitrate is electrolysed with silver electrodes. C. H. B. Mineralogical Chemistry. Graphite from Ceylon. By F. SANDBERGER (Jahrb. f. Min., 1887, ii, Mem., 12—16).—The author has examined a large number of specimens of graphite from the gneiss of Ceylon. The specimens were in the form of irregular masses, 5 to 8 cm. in diameter, forming layers 1 to 24 cm. thick round other minerals. In some cases, crystals were developed, the planes observed being coPco, P, P. In many places on the principal cleavage plane (coPco), needles were observed crossing one another at angles of 60° and 120°. These needles are mostly colourless, sometimes black. They resemble those in the mica of Ontario, and in the biotite from the mica diorite of Vöhrenbach. The colourless needles consist of rutile, whilst the few dark ferriferous needles appear to be pseudomorphs of titaniferous iron ore after rutile. Colourless massive quartz with conchoidal fracture is the most frequent of the minerals which are surrounded by the graphite. Granular quartz is of rarer occurrence. In two specimens, the centre consisted of green orthoclase. In another case, the centre consisted of olive-green apatite; whilst in other cases the centre consisted of kaolin, formed from the alteration of triclinic felspar. (Compare Abstr., 1886, 774.) B. H. B. Recent Formation of Marcasite at Marienbad. By E. PALLA (Jahrb. f. Min., 1887, ii, Mem., 5-7).-Hollow tubes of pyrites are found in the peat bog of Marienbad. They are casts of plant remains, and are found to be composed of marcasite. Their sp. gr. is 4:46. Analysis of the bog water gave the following percentages : The water of the bog containing the pyrites-mass is thus remarkable for the percentage of ferrous sulphate and of gypsum. The recent formation of the pyrites appears to be due to the reduction process brought bout by the presence of plants in the ferrous sulphate. B. H. B. Percylite, Caracolite, and Phosgenite from Chili. By F. SANDBERGER (Jahrb. f. Min., 1887, ii, Mem., 75-77).-A specimen of galena in a dark quartzose gangue, from the Sierra Gorda in Chili, is covered with yellow, blue, colourless, and white crusts of substances of more recent formation. Careful examination shows that these crusts occur in regular order, the blue substance being older than the colourless, and the colourless older than the white. The blue sub. stance is lead-copper oxychloride, or percylite. The colourless substance is caracolite. The white mineral occurring above this appears to be a new compound of phosgenite (PbCO,,PbCl) with sodium sulphate. All these minerals are undoubtedly products of the action of a salt solution on a mineral vein containing bournonite and galena. B. H. B. Minerals from the Sjö Mine, Sweden. By L. J. IGELSTRÖM (Jahrb. f. Min., 1887, ii, Mem., 8-11).-The Sjö mine, in the parish of Grythyttan, Oerebro, Sweden, is a small mine only a few fathoms in depth. Exploratory workings, however, have shown that the ore deposit extends for a considerable length. The mine is a very ancient one, and, after having been abandoned for centuries, it was re-opened in 1885. The ore bed has a thickness of 5 metres, and the ore, braunite and hausmannite, is very rich and pure. Adjoining this manganese ore bed is a bed of iron ore, hæmatite, and magnetite of poor quality. Both ore beds are enclosed in dolomite, which forms a bed in the granulite nearly a mile in length, and several hundred. yards in width. The braunite and hausmannite of the Sjö mine are accompanied by a large number of remarkable minerals, such as xanthoarsenite (Abstr., 1886, 25), hæmatostibiite, polyarsenite, and pyrrhoarsenite. The minerals usually met with in this mine are the following:-Tephroite, iron glance, magnetite, calcite, garnet, rhodonite, specular iron ore. Barytes, chlorite, neotocite, and galena are of rare occurrence. Pyrrhoarsenite, a mineral discovered by the author in July, 1886, is an anhydrous arsenate of manganese, calcium, and magnesium, containing 17 per cent. of manganous oxide. B. H. B. Mineralogical Notes. By V. v. ZEPHAROVICH (Jahrb. f. Min., 1887, ii, Ref., 21).-1. Pyroxene from the Krimlerthal.-On the crystals, the predominating planes are coPco, coP∞, P∞, ∞P. The plane P is very small, and the planes coP3, coP3, 2F∞, +P, +2P, are of rare occurrence. Analysis gave the following results : SiO2. Al2O3. FeO3. FeO. MnO. MgO. CaO. 10.60 21.59 Na O. 2:06 The angle made by the direction of extinction with the vertical axis on cleavage plates parallel to coPoo is 46° 40'. 2. Scheelite from the Krimlerthal. The crystals exhibit the planes Poo, Poo, 3P3, P, P3, 2P2, the last being new for this mineral. B. H. B. |
