ON THE MECHANICAL PROPERTIES OF METALS. 87 



been in communication with James M. Rendell, Esq., V.P. Inst. C.E., the 

 Engineer-in-Chief of the Works, and have derived from him every aid that 

 could be desired. I have also been in communication with the Astronomer 

 Royal, with a view to obtaining the use of some time measuring instruments, 

 and derived some useful suggestions from his experience in arrangements 

 analogous to those proposed. I expect therefore early next spring to proceed 

 with these experiments at Holyhead. 



I cannot close this brief report without congratulating our fellow-workers 

 in Physical Geology upon the increased attention now given toseismological 

 observation and reseai'ch, to which the several reports published by the 

 British Association, and by various authors, have no doubt been instrumental ; 

 the arrangements, now understood to be in progress under the Board of Ord- 

 nance for earthquake observations in the Mediterranean, are a welcome sign 

 of progress. 



On the Mechanical Properties of Metals as derived from repeated 

 Meltings, exhibiting the maximum point of strength and the causes 

 of deterioration. By William Fairbairn, F.R.S. S^c. 



This inquiry was undertaken at the request of the British Association, to 

 determine certain anomalous conditions which present themselves in castings 

 when produced from the same iron in successive meltings. It is a generally 

 acknowledged opinion, that iron is improved up to the second, third, and 

 probably the fourth meltings ; but that opinion, as far as I know, has not 

 been founded upon any well-grounded fact, but rather deduced from obser- 

 vation, or from those appearances which indicate greater purity and increased 

 strength in the metal. 



Those appearances have, in almost every instance, been satisfactory as 

 regards the strength ; and the questions we have been called upon to solve in 

 this investigation, are, to what extent can these improvements be carried 

 without injury to the material ; and \yhat are the conditions which bear more 

 directly upon the crystalline structure, and the forces of cohesion by which 

 they are united. 



In the following research I have endeavoured to supply these desiderata ; 

 and having in the course of the inquiry made a careful selection of the 

 material, the subjoined experiments were instituted, and from which some 

 curious and interesting results were obtained. In preparing the iron, coke, 

 and flux requisite for ensuring sound castings, it was found necessary, for 

 the sake of comparison, to have them cast under circumstances precisely the 

 same ; and in order to ensure, as nearly as possible, perfect uniformity in the 

 castings, a furnace was prepared for the express purpose, and from 18cwt. 

 to a ton of No. 3 Eglinton Hot-blast iron was melted and run into bars and 

 pigs with 388 lbs. of coke, and 224 lbs. of lime as a flux. 



The proportions of coke and flux were carefully observed in the first and 

 throughout the whole of the subsequent meltings. They were accurately 

 weighed every time the furnace was charged, and each charge was made 

 under the same circumstances, and as nearly as possible with the same quantity 

 of blast. In the first melting, three or four bars, each 5 feet long and 1 inch 

 square, were cast, and the remainder of the iron fused was run into pigs, and 

 preserved for re-melting along with the fiactured bars used in the first ex- 

 periment. In the succeeding experiments, the bars and pigs were prepared 

 and re-melted in the same way ; and thus, by a continued succession of re- 



