TEANSACTIONS OF SECTION B. 



595 



These niim'bers are entirely different from those given by Calvert, but they sup- 

 jport the suggestions of Snelus ' relative to chemical changes during remeltino-. 



5. Silicon in Cast Iron. By Thomas Turner. 



The author has prepared samples of cast iron containing various amounts of 

 silicon, and has examined the properties of the product." Cast iron of exceptional 

 purity was prepared by heating wrought iron with charcoal, and to this diiferent 

 quantities of silicon pig were added. The chemical composition of the materials 

 used was as follows : — 



The mixtures obtained were examined both chemically and mechanically, and 

 the results are given in the accompanying table. The tensile and crushing strength 

 was determined by Professor A. B. W. Kennedy, while for assistance in the chemical 

 analyses the author is indebted to Mr. J. P. Walton. 



It will be seen that the addition of silicon to white ii'on causes the separation of 

 graphitic carbon, and produces a grey iron. The effect is therefore to soften the 

 iron. By suitable addition of silicon an iron of any desired softness may be pre- 

 pared without extra expense, and the author believes that with care in mixing the 

 strength of cast iron could readily be doubled in many cases. A number of manu- 

 facturers have already applied the conclusions deduced from these experiments with 

 very beneficial results. 



As illustrating the practical value of these researches, the author referred to the 

 work of Mr. C. Wood, who has been using siliceous iron in the foundry with marked 

 success diu-ing the past twelve months. By this means Mr. Wood is able to prepare 

 castings with a uniform tensile strength of 12 tons per square inch, using entirely 

 Middlesborough iron. He is also able to make perfectly soft, smooth, soimd 

 castings, and to obtain grey iron even in sheets not exceeding one-eighth of an inch 

 in thickness. 



The author has recently had an opportunity of performing some experiments at 

 the Rosebank Foundry, Edinburgh. Of these, and of other results obtained at this 

 foundry, he hopes to give an account shortly. In the meantime he takes the oppor- 

 tunity to say that his former conclusions are quite confirmed. Six-test pieces of 

 cast iron were exhibited with tensile strength varying from 15-8 to 18| tons per 

 square inch, the average being nearly 17 tons ; a result which, so far as the author 

 is aware, has never before been obtained with British cast iron. These samples 

 were not unusually hard to the tool, and the author believes that at such results as 

 these the founders connected with our leading engineering works should aim. 



' Journal Iron and Steel Institute, vol. i. p. 37. 



2 Joitr. Cltem Soo. 1885, pp. 577, 902; 1886, p. 130. Journ. Iron and Steel Insti- 

 tute, 1886, Part I. Iron, xxvii. p. 476. Jour. Soc. Chem. Industry, 1886, p. 289. 



Q Q 2 



