ON STANDARDS FOR USE IN ELECTRICAL MEASUREMENTS. 69 



again between 1879 and 1882. This would be accounted for if we sup- 

 pose that Hockin's platinum silver standard was too low. 



P.S. — November 1888. — Since the experiments detailed above were 

 completed a considerable change has taken place in F. It is now almost 

 exactly equal to Flat, that is, it has risen in value by '00048 B.A. Unit. 

 Further investigations as to the cause of this must be left till the next 

 report. 



Second Report of the Committee, consisting of Professors Tilden 

 and W. Chandler Roberts-Austen and Mr. T. Turner {Secre- 

 tary), appointed for the purpose of investigating the In- 

 fiaence of Silicon on the pjroperties of Steel. {Draivn up by 

 Mr. T. Turner.) 



In the previous Report of this Committee, presented at the Manchester 

 meeting, an account was given of a series of experiments undertaken in 

 order to determine the eiFect produced by silicon on the properties of the 

 purest variety of iron met with commercially. For this purpose metal was 

 taken from the basic Bessemer vessel at the end of the blow, before any 

 carbon or manganese was introduced, and to this fluid metal weighed 

 quantities of silicon pig, containing about 10 per cent, of silicon, were 

 added. It was then shown that silicon rendered the metal quiet in the 

 mould, and that in the proportions employed the metal was tough when 

 cold, and welded well. The elastic limit and tensile strength were both 

 increased by the presence of silicon, while the elongation and contraction 

 of area were diminished ; the appearance of the fracture also changed 

 from silky to crystalline, and with over 013 per cent, of silicon in all 

 cases the metal was so red-short that the ingots crumbled to pieces under 

 the rolls. 



The present Report has to do with a series of experiments very similar 

 to those described last year, the chief difference being that ordinary basic 

 ingot metal was used instead of the specially pure iron previously 

 employed. In these experiments, therefore, the metal has been taken 

 in the condition in which it would be sent into commerce, definite 

 quantities of silicon have been added, and the product examined both 

 chemically and mechanically. The method of procedure was as follows : 

 In a covered fireclay crucible a weighed quantity of the silicious iron was 

 melted, and into the red-hot crucible was run about 40 lbs. of molten 

 metal, which was taken from the ladle about the middle of a cast. After 

 allowing the contents of the crucible to stand for about a minute, the 

 metal, which was still thoroughly fluid, was poured in to another red-hot clay 

 crucible, in which the mixture was allowed to solidify. By this means a 

 very thorough incorporation of the materials was obtained. The experi- 

 ments were conducted, as before, at the works of the South StaSbrdshire 

 Steel and Ingot Iron Co., Bilston. Mr. F. W. Harbord kindly super- 

 intended the works tests of the material •, the mechanical tests were con- 

 ducted by Professor A. B. W. Kennedy, and in each case duplicate experi- 

 ments were made ; the chemical analyses have been performed by Mr. 

 J. P. Walton. 



