[ 353 ] 



XI. BAKKHIAN LK.ITIKI:. Tin- ('///*/.////, Xt,-tirtnre of Metal*. 



l>>l J. A. EWIM;. I-'. U.S.. /'/"/; .s.vo/- <//' Mif/Kiniinn and Applied Mechanics in the 

 !',,,'>; ,.,;/,, n f C,nnlir'nlti<\ "/"/ WALTER RosENliAiN, SY. Johns Colleyc, Cam- 

 l>ri</!/<\ 1851 K.rliiliit'"',, Research Scholar, University uj Melbourne. 



RccTi'vi'd and Kead May 18 Revised June 30, 1899. 



[PLATEN 15-28.] 



TIIK microscopic study of metals was initiated by SORBY,* and has been pursued by 

 ARNOLD, ANDREWS, BEHRENS, CHARPY, CHERXOFF, HOWE, MARTENH, OSMOND, 

 ROBERTS-AUSTEN, SAUVEUR, STEAD, WEDDING, WERTH and others, t The work of 

 these authors has demonstrated the value of the microscope in metallurgy, not only 

 a.s iii i ;iid to analysis, but as a means of observing structure. The structure of pure 

 metals, of metals containing small quantities of foreign matter, and of alloys, has been 

 made tin- subject of microscopic examination, and important conclusions have been 

 ivai-1 inl. The work to be described in this paper proceeds on the same general lines. 

 A large part of it deals with a branch of the subject which has not hitherto received 

 much notice, namely, the effects of strain. The writers Ijelieve that they have 

 established the fact that the structure of metals is crystalline even under conditions 

 \\hich might IHJ supjK>sed to destroy crystalline structure. They have found that the 

 plastic yielding of metals when severely strained occurs in such a manner that the 

 crystalline structure is preserved. The observations to be described show how 

 crystalline aggregates exhibit plasticity, and how, after straining, a metal continues 

 to l>e a crystalline aggregate. The distinction which is often drawn between crystal- 

 line and iion-i'i ystalline states in metuls ap]>ears to be unfounded. 



Kxcept for a few simple innovations, the methods of experiment used in this 

 irsraivli. especially as regards the preparation of sjKJcimens, do not differ materially 

 from those of earlier workers. The specimens were first ]>olished on commercial emery- 

 paper which had been previously rublxxl on a piece of hard steel in order to remove 

 the roai-ser particles. They were finished on a rapidly revolving disc coated with fine 

 wash-leather and charged with a thin {wiste of rouge and water. For most purposes 



* 'Roy. Soc. Proc.,' vol. 13, p. 333. 



t For the hihliograpliy st-r Sir \V. IJi H-.KKTS AISTKN'S )>ook on ' Metallurgy ' (Edition of 1895); also 



liy Mr. J. E. STKAD on tin? "Crystalline Structure of Iron and Steel," 'Journal of the Iron and 



Institute,' 1898. 

 \oi..i.\ciil. A. 2Z L's.li'.'.".' 



