ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 351 



METALLOGRAPHY. 



Some Theoretical Principles of Alloying. — Robert J. Anderson 

 {Chemical and Metallurgical Engineering, August 25, 1920, 23, Xo. 8). 

 A discussion of possible applications of such general concepts as may be 

 drawn from the equilibrium diagram, heat of alloy formation, thermit 

 reaction, diffusion and solution to problems connected with the produc- 

 tion of aluminium-copper alloys in the foundry. 



Studies of the Macrostructure of Cast Steel. — Fred. G. Allison 

 and Martin M. Rock {Chemical and Metallurgiccd Engineering, Sept. 1, 

 1920, 23, No. 9). Simple and reliable procedure is outlined for the 

 development and record of macrostructure. A peculiar banded structure 

 is described. Symmetrical arrangement of dendrites is necessary for 

 consistent physical tests. Pouring cold metal suppresses dendrites. 



Some Commercial Heat-treatments for Alloy Steels for Structural 

 Purposes. — A.. H. Miller {Chemical and Metallurgical Eagineermg, 

 July 21, 1920, 23, No. ;->). A general discussion of principles of heat- 

 treatment, having especial reference to a nickel-chromium steel, the effect 

 of time in complex heat- treatments, and the development of simple heat- 

 treatments from the complex. 



The Crystalline Structure of Antimony. — R. AY. James and N. 

 TuNSTALL iyPhd. Mag., August, 1920). This research follows the lines 

 laid down by Professors W. H. and W. L. Bragg. It is remarkably 

 interesting in view of the structure of antimony and its alloys as usually 

 seen microscopically. F. I. G. R. 



On the Electrical Conductivity of Copper Fused with Mica. — 

 A. L. Williams and Others {Phil. Mag., Sept., 1920). It is found 

 that samples of copper fused with mica exhibit a very large fall in 

 resistance when gradually subjected to rising temperatures. Photomicro- 

 graphs of specimens at different magnifications are given. The illumi- 

 nation in some cases was oblique, in others direct. Ammonia was 

 employed as the etching re-agent. F. I. G. R. 



The Economic Selection of Coal. — A. L. Booth (Iron and Steel 

 Institute Meeting, Sept., 1920). Although dealing chiefly with coal 

 from the industrial standpoint, the author gives much information of 

 interest to microscopists, including a number of coloured plates prepared 

 from photomicrographs. F. I. G. R. 



Temper -brittleness of Nickel-Chromium Steels. — R. H. Greaves 

 and J. J. A. Jones (Ironand Steel Institute Meeting, Sept., 1920). The 

 paper deals with (1) the range in which temper-brittleness is produced ; 

 (2) the rate at which temper-brittleness is produced ; (3) the suscepti- 

 bility of certain steels to develop temper-brittleness ; (4) the effect of 

 the change from the brittle to the tough condition on a few of the 

 physical properties of the steel. F. I. G. R. 



