On a rapid method for the accurate recognition of sulphides, arsenides, antimonides, and double compounds of these bodies with metals

Abstract

T HE process to be described has been applied to the minerals mentioned below, but I have no doubt that all similarly constituted minerals will also be easily recognised by the method.I am quite sure that all mineralogists have experienced much annoyance and difficulty in obtaining really satisfactory results with the ordihary blowpipe reactions in regard to some of the compounds of arsenic, antimony, and sulphur with metals, particularly in the separation of the metal or metals from the above-mentioned elements. In order to obtain the metal the assay requires a most careful and tedious roasting on charcoal in the ozidisi~g flame of the blow-pipe, in order to volatilise away the sulphur, arsenic, or antimony. When this roasting is complete the residue (oxide) is mixed with either sodium carbonate, or that salt and cyanide of potas. slum, and fused for a considerable time on charcoal in the reducing flame in order to obtain a bead of the metal. Sometimes borax is used to eliminate a metal from a mixed oxide residue, dissolving one oxide and leaving the other: If the oxides left after the oxidising process above-mentioned are not soluble in borax, then the bead which is obtained in the subsequent reducing process is an alloy, and practically useless as a means of recognition of the metals entering into its composition. Having often been disappointed with the results obtained by the above-mentioned blow-pipe processes, I determined to find, if possible, a more rapid and certain method of analysis of minerals.The apparatus required is that which all mineralogists have been in the habit of using for a long period, viz.1st. Small porcelain crucibles. 2nd. Test-tubes. 8rd, A small platinum basin and a platinum crucible.