vi Proceedings. [No2>ember^t/i,igij. 



A paper entitled " Note on some products isolated 

 from Soot," by Professor Edmund Knecht, Ph.D., and Miss 

 Eva Hibbert, was read by the former. 



This paper is printed in full in the Memoirs. 



Professor H. C. H. Carpenter, M.A., Ph.D., read a paper, 

 entitled "The crystallising properties of electro-deposited 

 Iron." Specimens of electro-deposited iron sheet of a high 

 degree of purity have been found to exhibit remarkable re- 

 crystallisation effects when heated above the Ac3 change and 

 then cooled below the Ar3 change. In this way relatively 

 enormous crystals are formed in three seconds after cooling 

 below Ar3. The coarse crystals are sometimes "equi-axed" 

 and sometimes "radial." Frequently both types occur on the 

 same specimen. There is no reason for thinking that they are 

 constitutionally different, and they are most probably a iron. 

 These crystallisation effects are only obtained when the thickness 

 of the iron sheet or strip does not exceed a certain critical figure, 

 which is between o'oii and o"oi2 of an inch. Once the coarse 

 crystals are formed they cannot be destroyed, except either by 

 mechanical work, or by heating above Ac3 followed by quench- 

 ing, or by very prolonged heating above AC3 followed by ordinary 

 cooling rates. 



The very heat treatment which produces coarse crystals in 

 the electro-deposited iron refines wrought iron and very mild 

 steel that have been rendered coarsely crystalline by "close- 

 annealing" between 700'' and 800° C. On the other hand, 

 annealing at 700° to 800" C. has no effect in coarsening the 

 structure of the electro-deposited iron which has been refined 

 by cold mechanical work. In these respects, therefore, the 

 behaviour of electro-deposited iron is precisely the opposite of 

 that of wrought iron and mild steel. 



