56 SECTIONAL ADDRESSES. 



arsenic on the copper used for the fireboxes of locomotives. The 

 report showed that the presence of from "S-l per cent, of arsenic was 

 highly beneficial. The third report dealt with electric welding and 

 the production of alloys of iron and aluminium. The fourth report 

 is particularly valuable, as it contains a resume of the Bakerian Lecture 

 given by Eoberts-Austen on the diffusion of metals in the solid state, 

 in which he showed that gold, even at as low a temperature as 100°, 

 could penetrate into lead, and that iron became carbonised at a low 

 red heat by contact with a diamond in a vacuum. In 1899 the fifth 

 report appeared, on the effects of the addition of carbon to iron. This 

 report, is of especial importance, because, besides a description of the 

 thermal effects produced by carbon, which he carefully plotted and 

 photographed, he described the microscopical appearance of the various 

 constituents of iron. The materials of this report, together with the 

 work of Osmond and others on steel and iron, provided much of the 

 material on which Professor Bakhuis Eoozeboom founded the iron 

 carbon equilibrium diagram. Eeference should also be made to the 

 very valuable paper by Stansfield on the present position of the solution 

 theory of carbonised iron {Journ. Iron and Steel Inst., 11, 1900, 

 p. 317). It may be said of this fifth report, and the two papers just 

 refeiTed to, that they foi^m the most important contribution to the study 

 of iron and steel that has ever been published. Although the diagram 

 for the equilibrium of iron and carbon does not represent the whole 

 of the facts, it affords the most important clue to these alloys, and 

 undoubtedly forms the basis of most of the modern practice of steel 

 manufacture. (Slide showing iron carbon diagram.) 



Many workers, both at home and abroad, were now actively engaged 

 in metallurgical work — Stead, Osmond, Le Chatelier, Arnold, Hadfield, 

 Carpenter, Ewing, Eosenhain, and others too numerous to mention. 



In 1897 Neville and I determined the complete freezing-point curve 

 of the copper-tin alloys, confirming and extending the work of Eoberts- 

 Austen, Stansfield, and Le Chatelier; but the real meaning of the 

 curve remained as much of a mystery as ever. Early in 1900 Sir G. 

 Stokes suggested to us that we should make a microscopic examination 

 of a few bronzes as an aid to the interpretation of the singularities 

 of the freezing-point curve. An account of this Avork, which occupied 

 us for more than two years, was pubhshed as the Bakerian Lecture 

 of the Eoyal Society in February 1903. Whilst preparing a number 

 of copper-tin alloys of known composition we were struck by the fact 

 that the crystalline pattern which developed on the free surface of the 

 slowly cooled alloys was entirely unlike the structure developed by 

 polishing and etching sections cmt from the interior; it therefore 

 appeared probable that changes were going on within the alloys as 

 they cooled. In the hope that, as Sorby had shown in the case of 

 steel, we could stereotype or fix the change by sudden cooling, we 

 melted small ingots of the copper-tin alloys and slowly cooled them 

 to selected temperatures and then suddenly chilled them in water. The 

 results of this treatment were communicated to the Eoyal Society and 

 pubhshed in the Proceedings, February 1901. (Slides showing effects 

 of chilling alloys.) 



