46 



KEPOKT — 1887. 



molten iron was taken from the Bessemer converter at the end of the 

 ' blow ' and before any addition of ferromanganese had been made. This 

 was mixed in a ci'ucible with various proportions of melted cast iron con- 

 taining about 10 per cent, of silicon, and the product was afterwards 

 examined. The composition of these materials was as follows : — 



In Table A is given a general summary of the results obtained. The 

 mechanical tests were conducted by Professor A. B. W. Kennedy, and 

 duplicate experiments gave concordant results. The mean values de- 

 duced from these experiments are given in Table B. The letter D is 

 used to indicate that in these cases it is doubtful if thorough mixture was 

 obtained. Other ingots were prepared containing more silicon, but as 

 these could not be rolled no mechanical tests were performed. 



Table B. — Mean Results of Tensile Tests. Professor Kennedy. 



The relative hardness was determined, as in my experiments on cast 

 iron, by means of the weight in grams necessary to produce a sci-atch 

 with a diamond on drawing its point over the smooth surface of the 

 metal. The following list will illustrate the values obtained on applying 

 such a method of examination to various substances. On comparing the 

 values given in Table B it will be seen that the relative hai-dness was not 

 very greatly influenced by the proportion of silicon added. 



Substances. Relative 



hardness. 



Steatite 1 



Lead (commercial) 1 



Tin „ 2-5 



Rock salt ........... 4 



Zicc (pure annealed) ......... 6 



Copper (pure annealed) 8 



Calcite 12 



Softest iron 15 



Fluor-spar ........... 19 



Mild steel 21 



Tyre steel . 20-24 



Good cast iroa . . 21-24 



Ear iron . 24 



