Journal . method. Hedissolves the iron in dilute hydrochloric acid, and passesthe evolved gases by means of ,a stream of hydi-ogenthrough dilute hydrogen peroxide (2-5 per cent.) contain-ing a little caustic soda, and determines the sulphuric acidas barium sulphate. In some cases, however, this is not acorrect method of determination, as a considerable propor-tion of the sulphur is not carried forward as sulphurettedbydrogen, but remains behind in the dissolving flask. Manyinstances are given showing the percentage of sulphur inthe residue to be 30 per cent., in some cases 50 per cent.,and in
Journal . method. Hedissolves the iron in dilute hydrochloric acid, and passesthe evolved gases by means of ,a stream of hydi-ogenthrough dilute hydrogen peroxide (2-5 per cent.) contain-ing a little caustic soda, and determines the sulphuric acidas barium sulphate. In some cases, however, this is not acorrect method of determination, as a considerable propor-tion of the sulphur is not carried forward as sulphurettedbydrogen, but remains behind in the dissolving flask. Manyinstances are given showing the percentage of sulphur inthe residue to be 30 per cent., in some cases 50 per cent.,and in one ease 100 per cent, of the total sulphur. Toovercome this difficulty the author recommends the ensuingmethod based upon the following reactions:— Fe + FeS + 2 CuCh,= 2 FeCK, + CuS + Cu CuS + Cu + 2 CuCL = 4 CuCl + S 5 of the iron are dissolved by 50 grms. of copper-ammonium chloride in 250 cc. of , containing 10 to r 2 646 *HE JOURNAL OP THE SOCIETY OF CHEMICAL INDUSTRY. [Sept. 20, 15 cc. hydrochloric acid. The solution is kept nearlyboiling till all or nearly all the copper is redissolved,generally about 15 minutes, and filtered at once throughasbestos. The residue is treated with a little chlorate ofpotash, 5 ce. nitric acid (14 sp. gr.), and IIJ cc. hydro-chloric acid (119 sp. gr.), evaporated to dryness, redis-solved, filtered, and sulphuric acid precipitated with bariumchloride. The industrial application of the principles of the abovereactions is suggested in connexion with copper extractionfrom burnt pyrites. The idea is to calcine half of the burntore with salt in the usual manner, lixiviate, and mix theextract with the unoalcined portion, by which means thecupric chloride reacts with the cupric sulphide and formscuprous chloride, which is dissolved by the salt. Thefollowing four advantages are claimed for this process :—(1.) Saving of half the cost of roasting. {2.) Saving ofnearly half of the hydrochloric acid. (3.) Saving of nearlyhalf of
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectchemist, bookyear1882
