104 president's address — SECTION B. 



heat and slag ; but, in a general way, these remarks characterise the 

 position. No variety of manoeuvring will get more silica, or more iron, 

 into the slag than the thermal conditions allow. The system of forces 

 in the converter, being left entirely to itself, only creates that phase 

 of results which is the easiest for itself. 



Behaviour of Copper as regards Loss, &c. — Needless to say, one of 

 the most satisfactory features of copper-converting is the small actual 

 copper loss sustained through the oxidation of the metal. With the 

 establishment of this fact fell the main dread entertained with regard 

 to the process. It seemed, a priori, inevitable that the rapid oxidation 

 of mattes should lead to a marked copper scorification. There was 

 the evidence of the Welsh process, with its heavy locking-up of values 

 in slags, in spite of its slowness, to support the suspicion. And yet the 

 latter was entirely unfounded. Except for mechanical losses, there is 

 no reason for anxiety — if the process is intelligently handled — that a 

 noteworthy copper loss will be suffered. And, in any case, the method 

 being properly only a refining method, its slags are available for return 

 to previous treatments, as is usual, if rich. As long as there is a sufficient 

 cover of protosulphide of iron, or sulphur enough to chemically bind 

 the copper, no apprehensions need be felt. In terms of oxygen the 

 heat of formation of copper oxide is only about one-half that of ferrous 

 oxide, while, as a further safeguard for the copper, its heat of combina- 

 tion with sulphur, in terms of equal weights of sulphur, is nearly the 

 same as that of iron. On the one hand, therefore, the energy required 

 to decompose the one, as compared with the other, finds the same 

 resistance in both, and there is no choice, while, after decomposition, 

 and relatively to the oxygen, the heat developed by the combustion 

 of the iron is twice as great as that from copper, and this reaction, 

 perforce, preferentially asserts itself. The protection of the copper 

 is thus complete, as long as there is a sufficiency of iron sulphide. In 

 addition, the potent bearing of the sulphur in combination is quanti- 

 tatively evidenced in favor of the copper by the circumstance that the 

 same weight of the metalloid covers and protects about two and one- 

 quarter times as much copper as it does of the corresponding iron. 



It may be proper to remark, however, that since the days of the 

 first pneumatic experiments with mattes the position of copper in 

 relation to sulphur has been assigned a much weaker place than was 

 given it in Fournet's empirically established series some 70 years ago. 

 His determinations placed copper at the head of the list in point of 

 affinity for sulphur — a position which, in ordinary metallurgical ex- 

 perience, would seem to be its proper station. In descending order 

 the seiies was : copper, iron, tin, zinc, lead, silver, antimony, arsenic. 

 The preciser knowledge of thermo-chemistry now, however, arranges the 

 metals in the following order, according to the respective heats of 

 formation of their sulphides : aluminium, magnesium, manganese, 

 zinc, cadmium, iron, cobalt, lead, copper, nickel, mercury, silve:, with 

 antimony and arsenic about on a level between zinc and iron. The 

 relative degree of affinity of copper for sulphur has thus been con- 

 siderably lowered from its ancient eminence. However, as a matter 



