president's address— section b. 79 



lieated to softening in a reverberatory furnace, and a fine sprav of 

 water then thrown on the surface, in the expectation that it would be 

 at once dissociated, and that sulphur, arsenic, and antimony would 

 enter into combination with the hydrogen, while the oxygen would 

 combine with the non-volatile elements, iron, lead, tin, and a portion 

 of the copper, and these oxides would be scorified by the furnace 

 lining. A second operation was to follow, consisting of the injection 

 of an airblast, ostensibly to oxidise the balance of the foreign elements ; 

 the copper then to be brought to pitch in the usual way. Another 

 proposal of the time, pursuing the same general scheme, was that of 

 Guiilemin. It advocated the introduction of a current of steam to 

 the bottom of the metallic bath, in a reverberatory furnace, through 

 channels of fire-resisting material, or metal pipes protected by re- 

 fractory substances. Similar attempts by others also led to no result, 

 and the reasons were clearly set forth by Wedding (m) in 1869. Molten 

 copper does not decompose steam, whereas the impurities do, at least 

 partially, and are oxidised with the evolution of hydrogen. But, 

 considering the relative quantities of these impurities and the copper, 

 it was hopeless to expect that antimony and arsenic, or lead and bis- 

 muth, would be sensibly removed by steam. Still, the method would 

 probably contribute to their easier elimination, merely in consequence 

 of an increased exposure to the atmosphere, as an incidental conse- 

 quence of the ebullition of the bath caused by the steam. As regards 

 the sulphur in the copper, both this quasi-mechanical ?nd the direct 

 chemical effect might, with some confidence, be looked forward to. 

 Wedding's experiments corroborated this, but the manipulative diffi- 

 culties attending the work were too great. The admission of dried 

 superheated steam of 221bs.to 241bs. pressure fully achieved the mechani- 

 cal effect referred to, though it was true that ordinary poling had the 

 same result. Still, this cannot, of course,, be carried out at the same 

 stage of the refining process, because the reducing action of the hydro- 

 carbons present prevents the oxidation of the impurities. Neverthe- 

 less, it was inferred that even the subsequent toughening process could 

 probably be more rationally carried out by means of a judicious applica- 

 tion of steam than it is currently performed with the aid of the wholly 

 irregular and uncertain moisture contents of a pole of green wood. 



A further proposal of the same general class was that of Tessie 

 du Motay, in 1869, who endeavored to use oxyhydrogen gas for the 

 production of steam in copper-refining ; and still another scheme was 

 that of MM. Laveissierrt, expressed in a patent of 1874, for improve- 

 ments in the refining of metals other than copper, which consisted in 

 the employment of a Bessemer apparatus, utilising preheated gases, 

 such as oxygen, air, steam, &c. This reference may close the list of 

 processes having for their object the purification of metallic copper 

 by any sort of rapid oxidation process. It may be taken for granted 

 that steam-refining efforts have practically come to an end. In view 

 of the ease and certainty with which the Bessemer process casts out 

 the deleterious elements during the conversion of mattes into blister, 



{m) Preiiss. Zeitschr. f. Berg-u. Hiittenwesen, 1870, vol. XVIII., p. 211. 



