330 Chemical Society. 



May 18. — An extract of a letter from Mr. Maugham was read, 

 " On the Mode of treating Copper Ores, and the Ores of other 

 Metals combined with Sulphur, so as to ascertain the quantity of 

 Sulphur in such Ores, and also the quantity of Copper in the native 

 Sulphuret." 



A quantity of the powdered ore, sulphuret of copper, about 50 or 

 100 grains, is placed in a porcelain tube traversing a small furnace, 

 and made red-hot ; after remaining for 5 or 6 minutes a portion of the 

 sulphur will be expelled ; a stream of oxygen gas is then passed over 

 it, the remaining sulphur is then rapidly given off as sulphurous and 

 sulphuric acids, and the copper thoroughly oxidized. By heating the 

 ore when first introduced into the tube it becomes slightly adherent, 

 which prevents any of it from being blown away by the oxygen gas. 

 The contents of the tube are then removed into an assay crucible, 

 with the addition of black flax and a little charcoal ; the whole co- 

 vered with dry carbonate of soda or borax, and submitted to a yellow 

 heat, when a button of copper is obtained. Mr. Maugham finds 

 that arsenic and other volatile metals that may happen to be present, 

 are oxidated and expelled by the heat ; but should tin be present it 

 will be found with the reduced copper, and must be removed in the 

 usual way. The process is known to be complete when no more 

 vapours are seen to issue from the tube, or when the odour of sulphu- 

 rous acid is no longer perceptible. It is, however, to be observed, 

 that white vapours will be seen even after the process is complete, 

 owing to a portion of sulphuric acid condensed in the tube returning 

 to the hot part. An assay of this kind takes about twenty minutes 

 to execute. 



When the wet analysis is desirable, we have only to proceed as 

 before in the tube part of the process, and to dissolve the residue in 

 the proper acids. 



Mr. Maugham speaks favourably of the use of chlorate of potash, 

 added to hydrochloric acid, for dissolving certain ores where nitro- 

 muriatic acid is generally employed, and afterwards expelling the ex- 

 cess of chlorine by heat ; the known inconveniences of nitric acid in 

 certain cases are thus avoided. 



The quantity of sulphur contained in the ore is ascertained by 

 elongating the tube traversing the furnace, so that it may dip into 

 a vessel containing water saturated with chlorine, by which means 

 the sulphurous acid is converted into sulphuric acid, and the quantity 

 of sulphur found from the precipitate with chloride of barium. 



A paper was read "On the Atomic Weight of Carbon," by Pro- 

 fessors Redtenbacher of Prague and Liebig of Giessen*. 



June 1. — Extract of a letter from Col. Yorke " On a Specimen of 

 Artificial Arragonite." 



" This substance was taken from the interior of a copper boiler 

 which was used to supply hot water for household purposes at Port 

 Eliot, Lord St. Germaine's seat in Cornwall. The substance is about 

 •j^jths of an inch thick, and by its non-conducting power it caused, 



* This paper is given entire in our last Number, p. 210. 



