Hungary If the ores are easily fusible, 5 grammes (77.16 grains) are charged with a flux composed of 2 parts of calcined borax and 1 part of glass free from iron, by placing a mixture of ore and 11.5 grammes (177.47 grains) of flux in the bottom of the crucible, upon this 23 grammes (354.94 grains) of flux, and on the top 8 to 10 grammes (123.46 to 154.32 grains) of common salt. This is fused in the muffle furnace. When the ores are refractory, 1.25 grammes (19.29 grains) are fused with the same flux, and 3.2 grammes (49.4 grains) of a pure easily fusible concentrated pyrite ore, the percentage of matt contained in this being afterwards deducted; or, with 0.25 to 3.5 grammes (3.85 to 54.01 grains) of copper as a collecting agent. Pribram: 5 grammes (77.16 grains) are mixed with the quantity of a flux consisting of 10 grammes (154.32 grains) of borax, 2 grammes (30.87 grains) of glass, and 0.4 gramme (6.17 grains) of coal dust. The remaining part of the flux is strewn over this, and on top a cover of common salt and fragment of coal. 0.05 gramme (0.77 grain) of copper may be added to the roasted, and as much as 0.2 gramme (3 grains) to unroasted ores. The crucible, with luted cover, is gradually heated to a moderate red heat in an anthracite furnace (p. 56), and then fused for from 30 to 35 minutes at a bright red heat.— Slags with mechanical inclosures of matt are charged in the following manner: 30 grammes (462.97 grains) of slag, 20 grammes (308.64 grains) of borax, and 50 grammes (771.61 grains) of glass with a covering of common salt and a fragment of coal. The charge is fused forto of an hour at a bright red heat. B. Wet assays.2 1. Gravimetric assay.-1 gramme (15.43 grains) of ore is decomposed by fuming nitric acid, then nearly all the nitric acid removed by boiling. Hydrochloric acid is now added and heat is applied, when the sulphur will be quickly dissolved (the heating should not be continued too long, or loss will ensue by the escape of sulphuric acid). The solution is then evaporated to dryness, the residue is heated with hydrochloric acid in order to expel the nitric acid (as otherwise the results would be too high). The liquid is now diluted B. u. h. Ztg. 1871, p. 255. and filtered, the filtrate precipitated with barium chloride, and the barium sulphate filtered through impervious Swedish paper, dried, ignited, and weighed (BaSO4, with 34.356 per cent. SO, and 13.73 per cent. S). The sulphur in pyrites, roasted pyritous ores, and the same lixiviated,' is determined by heating 0.5 gramme (7.71 grains) of the substance in a platinum crucible, together with 10 parts of a mixture of 2 parts of sodium carbonate and 1 part of saltpetre. This is lixiviated, etc., and finally precipitated by barium chloride, etc., as above.-Process for determining small quantities of sulphur in materials and products of the iron-works at Creuzot.2 The substance is heated in a porcelain tube, and a mixture of of hydrogen and carbonic acid is conducted over it. The sulphuretted hydrogen, which is formed, is led into an acid silver solution, and the quantity of sulphur calculated from the weight of the silver sulphide. 2. Volumetric assays.3 a. 1 gramme (15.43 grains) of ore is intimately rubbed together with 2 grammes (30.87 grains) of pure saltpetre, or with 3 grammes (46.30 grains) of sodium carbonate and the same quantity of saltpetre. The mixture is placed in a small dish of sheet iron, 55 millimeters (2.16 inches) wide and 25 millimeters (0.98 inch) deep, which is placed in a scorifier (Fig. 37, p. 65). It is then gradually heated in a red-hot muffle. After fusing quietly from five to eight minutes, the small dish is taken out and allowed to cool off. The mass contained in it is then lixiviated with hot water and filtered into a small beakerglass. The residue is washed out with as little water as 1 Fresenius' Ztschr. 1877, p. 335. B. u. h. Ztg. 1877, p. 241. 2 Dingler, ccxxxiii. 124 (Rollet). 3 Muspratt's techn. Chem. vi. 9. Fresenius' Ztchr. i. 323 (Wildenstein). possible, and hydrochloric acid in excess then gradually added. It is now heated in a sand-bath, in order to expel the nitrous compounds. Titrated solution of barium chloride is then added drop by drop to the hot solution (which has been concentrated as much as possible), from a burette, divided into cubic centimeter (0.015 cubic inch), until no further white turbidity is formed in the supernatant liquid. 1 cubic centimeter (0.061 cubic acid) of a normal solution, with 0.152 gramme (2.34 grains) of barium chloride, precipitates 0.050 gramme (0.77 grain) of sulphuric acid, corresponding to 0.020 gramme (0.3 grain) of sulphur; or 5 per cent. of sulphuric acid and 2 per cent. of sulphur. Some experience is required to detect the final reaction. Indicators for this have been proposed, as, for instance, potassium chromate, by Wildenstein, or filtering off a few drops and adding barium chloride. According to Wildenstein, the solution containing sulphuric acid is diluted to a bulk of 45 to 55 cubic centimeters (2.74 to 3.35 cubic inches), to which is added a slight excess of titrated solution of barium chloride. It is then boiled for a half to one minute, a slight excess of ammonia free from carbonic acid having first been added. Titrated solution of neutral potassium chromate is now added in small quantities, which should not exceed cubic centimeter (0.03 cubic inch) at a time, in order to precipitate the excess of barium monoxide, until the liquid, after having been shaken and allowed to become clear, shows a distinct yellow color. It is then titrated back with a few drops of barium chloride until the fluid becomes colorless. During this operation the precipitate must be allowed to settle every time, or a few drops should be filtered off, and tested. Normal solutions: 1 cubic centimeter (0.061 cubic inch) of barium chloride: : 0.015 gramme (0.23 grain) of sulphuric acid, and 1 cubic centimeter (0.061 cubic inch) of solution of potassium chromate = 0.01 gramme (0.15 grain) of sulphuric acid. This assay gives accurate results to within per cent. of sulphur. b. Metallic sulphides decomposable by hydrochloric acid are treated with it in a flask connected with a retort (Fig. 61, p. 253). The sulphuretted hydrogen developed is introduced into a titrated solution of iodine in potassium iodide (SH2+I2=21H+S), and the unchanged iodine titrated with sodium hyposulphite' (p. 254). XIX. FUELS. 75. FUELS.2 These may be in either of the following forms: solid (raw or natural, carbonized, or artificial, agglomerated or patent fuel briquetts); or liquid (petroleum, tar-oils); and gaseous (natural gas, waste and generator gases, illuminating gas). The different varieties of raw fuel are, approximately, composed as In order to remove earthy admixtures from fossil fuel before subjecting it to docimastic test, it is comminuted and stirred into sulphuric acid of 1.4 specific gravity (in soda manufactories, in a solution of sodium sulphate3). The heavier earths will fall to the bottom, while the coal rising to the surface is removed with a spoon, thoroughly washed, and dried. 1 Dingler, ccx. p. 184. 2 Kerl, Grundr. der allgemeinen Hüttenkunde, 2 Aufl., 1879, p. 64. Muck in B. u. h. Ztg. 1876, p. 286 (Steinkohlen). 3 Dingler, cxc. 76. 76. ASSAYS OF FUEL. The examination extends to the following points, on which the value of fuel chiefly depends: 1. Determination of the amount of hygroscopic water. -5 grammes (77.16 grains) of the powdered sample are placed in a watch-glass and heated on a water-bath (raw fuel), or (wood-charcoal, coke) at a higher temperature (120° to 150° C., 248° to 302° F.) in an air-bath, or on a drying disk (Fig. 2, p. 26). It is allowed to become cold in the desiccator (Fig. 17 a, p. 43), and then weighed; is again dried and weighed until two weighings agree. 5 Air-dried wood and peat contain 15 to 20 per cent. of water; lignite, 10 to 15 per cent.; brown coal with a conchoidal fracture, 10 to per cent.; earthy coal, as much as 25 per cent.; bituminous and anthracite coal, fresh from the pit, 1 to 10 per cent.; wood-charcoal, 10 to 12 per cent.; coke, 5 to 10 per cent. 2. Yield of carbon.-5 to 10 grammes (77.16 to 154.32 grains) of the material, either in small fragments, or in the form of powder, are placed in a covered crucible (Fig. 42, p. 67), and gradually heated to a red heat in the muffle furnace, until the flame which shows itself at the lid of the crucible disappears. The residue, upon cooling, is weighed, and (in tests of coal) the physical condition of the coke is observed at the same time. This may be more accurately ascertained by heating 1 gramme (15.43 grains) of coal in a platinum crucible 40 millimeters (1.57 inches) high with a bottom diameter of 24 millimeters (0.94 inch), keeping the crucible at a distance of 3 centimeters (1.18 inches) over the flame of a gas-burner.1 The yield of carbon will vary according as the heat is raised more or less quickly, and with the degree of temperature, decreasing as the 1 B. u. h. Ztg. 1876, p. 287. |