14 TUCKER AND MOODY: THE PRODUCTION OF 11.-The Production of hitheyto unknown Metallic Borides. By SAMUEL AUCHMUTY TUCKER, Ph.B., and HERBERT R. MOODY, B.R., M.A. UNTIL the electric furnace made their formation comparatively easy, the borides were almost unknown and even now there have not as yet been reports concerning many of them. Moissan has described a few of these compounds, notably those of iron, cobalt, nickel, carbon, calcium, strontium, barium, and, lately, silicon.HITHERTO UNKNOWN METALLIC! BORfDES. 15 So far as they have been investigated, the borides present evidence of definite composition and crystallisation, they are stable and fuse at comparatively high temperatures. As a consequence of their high fusing point, hardness, and good crystallisation, it is quite possible that some of them may prove to have industrial uses.The available processes for the production of borides are two in number, In the first, the two elements are heated together in the electric furnace, and in the second, boron chloride is passed over the metallic element. The former of these was gelected as being the most practicable for the preparation of the borides described in this paper. The utmost care was taken t o prevent the addition of carbon, silicon, &c., t o the product in each case, and in our opinion the borides described were entirely free from these elements. The boron in each case was determined directly by Gooch’s method (Amer. Chem. J., 1887, 8, 23). Zirconium Boride.-The zirconium salt available for the preparation of this borido happened to be the nitrate.In order to reduce this to the elementary state, two processes were tried. I n the first, the nitrate was ignited until it was wholly converted to the oxide, This was then subjected to the regular Goldschmidt process, which did not prove to be satisfactory. I n the second, the nitrate was dissolved in cold water and the hydroxide precipitated from this solution by sodium hydroxide. Cold water was used in washing the precipitate, inasmuch [as hot water causes it to become insoluble. After being washed, the hydroxide was dissolved in hydrofluoric acid and to this solution neutral potassium fluoride solution was added, forming a precipitate of the double fluoride, 3KF,ZrF,. When dry, this salt was reduced by means of powdered aluminium and the cake thus formed was boiled for three days with concentrated hydrochloric acid.It was found impossible to filter the product rapidly, even with the aid of suction. After being washed with hot water, the metal was ready for we. The elementary boron was prepared by fusing boric acid and reducing the oxide thus formed with metallic magnesium, To remove magnesium salts, the cooled mass was boiled with dilute hydrochloric acid, filtered, washed, and then boiled for three days with hydrochloric acid of 8p. gr. 1.2. After filtering and washing, the residue mas boiled for several hours with hydrofluoric acid, and after a final washing it was dried. For preparing the zirconium boride, 15 grams of the zirconium were mixed with 2.2 grams of boron and the whole heated for 5 minutes in a carbon crucible with the aid of a current of 200 amperes and 65 volts, The product was a button, blackish on the outside, brittle, and of a steel grey colour on fracture.Under the microscope, it proved to16 PRODUCTION OF HITHERTO UNKNOWN METALLIC BORIDES. be an agglomeration of brilliant, tabular, translucent t o transparent crystals, many of these being colourless. It had B sp. gr. 3.7 and a hardness 8. It was slowly attacked by hot concentrated acids and aqua regia. Boiling liquid bromine attacked it feebly. Analyses of the compound were made and 86 per cent. of zirconium was found to be present. This corresponds very closely with the theoretical amount of zirconium in a boride in which zirconium is quadrivalent ; therefore the formula of this compound is undoubtedly Zr,B,.Chromium Boride.-This boride was made by heating a charge con- sisting of 10 grams of metallic chromium and 2.1 grams of boron for 6 minutes by the aid of n current of 175 amperes and 60 volts. The product was a well formed button, greenish on the outside and of a greyish metallic lustre on fracture. It had a sp. gr. 5, a hardness 8, was distinctly crystalline, and had a conchoidal fracture, It was weakly attacked by hot acids and was not altered by exposure to the sir. Analyses of the product gave 82 per cent. of chromium, a result which indicates CrB as the probable formula of the compound. Tzcngsten Boride.-As tungsten is closely related to chromium, it was selected as a promising element and a trial was made of its affinity for boron.The metal tungsten may be prepared from alkali tungstates by acidifying their solutions with hydrochloric acid. This causes the precipitation of the trioxide. After being dried, the trioxide can be reduced in the electric furnace, the charge used containing 10 parts of tungsten trioxide to one part of carbon. For the preparation of the boride, 4 grams of tungsten were mixed with 0.2 gram of boron and then heated for 5 minutes by the aid of a current of 175 amperes and 66 volts, This produced a good fusion and the product was silvery and metallic on fracture. It WRS very brittle and under the microscope was seen to be crystallised in perfect octahedra, It was slowly attacked by concentrated acids, and vigorously by aqua regia. Analyses of the product showed the presence of 89 per cent.of metallic tungsten, a result which indicated the formula to be WB,. Atolybdenurn Boride.-The final compound prepared was a boride of molybdenum. This was selected, as the element molybdenum is closely related to chromium and tungsten and the metal is rather easily prepared. The molybdenum was obtained by heating 300 grams of molybdenum trioxide and 30 grams of coke for 26 minutes with a current of 200 amperes and 65 volts. For making the boride, 6 grams of metallic molybdenum were mixed with 1 gram of boron and heated for 20 minutes by the aid of a current of 230 amperes and 70 volts. This gave a homogeneous button with a Its hardness was 8 and its sp. gr. 9.6.CONSTITUTION OF ACIDS OBTAINED FROM U-DIBROMOCAMPHOR. 17 hardness of 9. I t was quite brittle and on fracture showed a brilliant metallic lustre resembling that of pale brass. It was crystalline in structure, and its sp. gr. was 7.105. The substance was moderately attacked by hot concentrated acids and vigorously by hot aqua regia. The formula Mo,B, was given to this compound as the result of several analyses which showed the presence of 86 per cent. of molybdenum. An attempt to make the borides of copper or bismuth failed entirely ; in fact, there does not seem to be any affinity between boron and the membersof the copper group. COLUMBIA UNIVERSITY, NEW PORK.