Section B.— CHEMISTRY. 

 President of the Section. — J. E. Stead, F.R.S., F.I.C., F.C.S. 



THURSDAY, SEPTEMBER 1. 



The President delivered the following Address : — 



IPlates viii. -XI.] 



It was with considerable diffidence that I accepted the position of President of 

 this Section. The long list of illustrious and eminent chemists who have occupied 

 the chair in the past, scientists of the highest attainments, and usually professors 

 of our educational institutions, is indicative of the very high standard to be 

 followed. As, however, it was urged that a President with experience in the 

 metallurgy of iron and steel was desired, I bowed to the decision of the Council, 

 concluding that even as a mere layman I might, in this address, discuss one or 

 more subjects to which prominent metallurgists have for the past thirty years 

 directed their earnest attention, both in Europe and America. I refer to some 

 of the underlying phenomena connected with the effect of sulphur and silicon 

 on the carbon condition of commercial cast iron. 



The effect of sulphur and silicon on cast iron has received the attention of 

 Karsten, Percy, Weston, Howe, Keep, West, Dillner, Bachman, Summershach, 

 Wiist, Johnson, Stoughton, Hailstone, Longmuir, Adamson, Turner and Schuler, 

 Levy, and many others. They all agree in concluding that sulphur tends to make 

 iron white by retaining the carbon in the combined state, and that silicon tends 

 in the opposite direction. Professor Howe and Dr. Wiist have endeavoured to 

 arrive at the exact quantitative effect of sulphur and silicon in preventing or 

 facilitating the decomposition of the carbides. 



Howe recognised that the data available are insufficient on which to make any 

 final conclusion. 



Wiist found, by a series of trials, that in pigs containing 3'15 per cent, carbon 

 and about 1 per cent, silicon, on an average O'Ol per cent, sulphur prevented 

 the separation of 0"02 per cent, graphite, but that with 2 per cent, silicon its effect 

 was much less. 



It is the general experience, that the effect of sulphur depends on the propor- 

 tion, not only of silicon, but of the total carbon and manganese, and of the 

 temperature at which the iron is cast, and the size and temperature of the mould 

 into which the metal is run. Under some critical conditions 01 per cent, 

 sulphur may prevent the separation of 3 per cent, graphite. 



Howe's discovery — that the tendency of silicon, in increasing the decomposition 

 of the carbides, is rapid at first, especially as the silicon rises from zero to 0-75 

 per cent., and then slower and slower with each further increase — is very im- 

 portant; so also is the generalisation of Messrs. Charpy and Grenet — that the 

 separation of graphite on annealing iron which is initially white, containing the 

 whole of the carbon in the combined condition, begins at a temperature which 

 is the lower the greater the percentage of the associated silicon, and that the 

 separation of graphite, once begun, continues at even lower temperatures than 

 that at which it started. 



The evidence advanced by Phillips, Prost, Campredon, Schulte, and others — 

 that, on dissolving sulphurous irons in hydrochloric acid, all the sulphur is 



