558 Chronicles of Science. [Oct., 



The question of the exact nature of the changes involved in the 

 conversion of pig-iron into steel in the Bessemer process, or rather 

 of the composition of the pig-metal employed, is still a matter of 

 great uncertainty. That sulphur, phosphorus, and copper are in no 

 degree removed during the process, and that consequently these 

 impurities must be absent from the metal treated, is proved by all 

 the analytical investigations made in this country as well as in 

 Sweden and Austria. As regards the question of silicon, Professor 

 Jordan, of Paris, has recently pointed out, in a memoir published 

 in the ' Eevue Universelle,' the probability that the enormous heat 

 developed in the process is mainly due to the combustion of this 

 element, because the whole of the heat produced by the burning of 

 silicon to silica, of silicate of protoxide of iron in the slag, and the 

 subsequent formation is entirely retained in the metallic bath, while 

 that produced in the combustion of the carbon to carbonic oxide is 

 in great part carried out in the current of flame and heated gases 

 issuing from the mouth of the converter. The exactitude of this 

 view cannot of course be positively demonstrated, because neither 

 the calorific power of silicon nor its specific heat has yet been 

 determined. If, however, we assume with Professor Jordan, which 

 is not improbable, that these factors are the same for silicon as for 

 carbon, it can be shown that in the conversion of a pig-iron contain- 

 ing 4*25 per cent, of carbon and 2 per cent, of silicon that the 

 amount of heat developed by the combustion of the latter element is 

 more than six times as much as that obtained from the former. In 

 proof of this statement it is asserted that the Bessemer process could 

 only be successfully carried out at Terrenoire in France when the 

 metal was run direct from the blast-furnace to the converters, the 

 small proportion of silicon, about 1-J per cent., present being not 

 sufficient to allow it to be cast into pigs and remelted, as is usually 

 done. The dark grey No. 1 Bessemer pig-iron produced in Cum- 

 berland and Lancashire contains generally from 2 • 6 to 2 • 7 per cent, 

 of silicon. It appears to be probable, however, that when too much 

 silicon is present, or rather when its proportion as compared with 

 that of the carbon is too high, it may not be entirely removed in the 

 blowing. 



The separation of sulphur and phosphorus from iron has long 

 been a problem of much interest, especially so since the introduction 

 of the Bessemer process. At the Working Men's International 

 Exhibition at the Agricultural Hall, London, is a display of speci- 

 mens of iron obtained, by a process invented by Sir Antonio Brady, 

 from some of that dockyard refuse irreverently described as " Seely's 

 pigs," and which has been the subject of discussion both in Parlia- 

 ment and by the press. These pigs were of different qualities, but 

 were all largely contaminated with phosphorus and sulphur, and 

 were supposed to be of little or no value. The presence of phos- 



