ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 309 



Metallography, etc. 



Alloys of Copper and Zinc* — L. Guillet reviews recent progress 

 in the knowledge of the copper-zinc alloys, and gives the results of his 

 own investigations upon fifteen alloys in the range to 4-4 p.c. zinc. 

 The influence upon microstrncture, of hot-rolling, of cold-rolling, of 

 annealing, and of quenching from various temperatures, is described. 



Deformation of Copper at High Temperatures.! — A. K. Hunting- 

 ton gives results additional to those he has previously published upon 

 the effect of temperatures higher than atmospheric on tensile tests of 

 copper and its alloys. A number of photomicrographs of specimens 

 strained at various temperatures illustrate the author's conclusions. 



Coalescence in Steel and in Alloys. J — A. M. Portevin and A'. 

 Bernard discuss the coalescence of constituents of alleys brought about 

 by heat-treatment, and describe the microstructure of specimens of 

 bronze and of steel which had undergone heat-treatments intended to 

 induce the aggregation, into larger masses, of particular constituents. 

 Two copper-tin alloys containing respectively 16 and 25 p.c. tin were 

 heated in a salt-bath to 525° C, cooled (through the eutectoid tempera- 

 ture) in 5 hours to 475° C, rapidly reheated to 525° C, and again very 

 slowly cooled. The 8 constituent, originally finely divided, had coalesced 

 into large masses. Steels of eutectoid composition slowly cooled from 

 800° C. consisted of lamellar pearlite ; annealing for 30 hours at 700° C. 

 caused the formation of very perfect granular pearlite, a" photomicro- 

 graph of which, at 1200 diameters, shows globules of cementite em- 

 bedded in ferrite. A steel containing - 5 p.c. carbon, very slowly 

 cooled from 800° to 700° C, and more rapidly below that temperature, 

 contained no granular pearlite. Coalescence had begun in a specimen 

 slowly cooled from 800° to 700° C, maintained at 700° C. for 10 hours 

 and then air-cooled, while complete coalescence had occurred in a 

 specimen annealed for 30 hours at 700° C. and air-cooled, the steel then 

 consisting of free ferrite and granular pearlite. Re-solution of the 

 cementite does not occur in granular pearlite immediately on passing the 

 critical point on heating, but requires a certain duration of heating 

 above the critical point. 



Electrolytic Iron.§ — L. Guillet deals with the manufacture, pro- 

 perties, and uses of very pure electrolytic iron, and describes its 

 microstructure. On removal from the electrolyte bath the material is 

 hard and brittle, and consists microscopically of innumerable fine 

 needles, much resembling martensite. This structure dues not disappear 

 at 300° C, but it fades as the temperature rises, and disappears entirely 



* Rev. Metallurgie, xi. (1914) pp. 1091-1132 (26 figs.). 

 t Journ. Inst. Metals, xii. (1911, 2) pp. 234 (20 figs.). 



J Journ. Iron and Steel Inst.,xc. (1914, 2) pp. 204-2t2 (17 fL 

 § Journ. Iron and Steel Inst., xc. (1914, 2) pp. 66-81 (12 fig 



