ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 435 



METALLOGRAPHY, Ere. 



Crystal Growth and Re-crystallization in Metals.— Prof. H. C. H. 

 Carpenter and Miss C. F. Elam (Institute of Metals Meeting, Sept., 

 1920). The facts ascertained as the result of experiments are : — 1. The 

 largest crystals are formed after the minimum amount of stress sufficient 

 to produce growth. 2. The lower the temperature, the greater the stress 

 required to produce large crystals. 3. The increase in size is not gradual. 



F. L G. R. 



Monel Metal.— Paul D. Merica {Chemical and Metallurgical 

 Engineering, February 16, 1921, 24, No. 7). A brief statement of the 

 physical properties of this natural alloy, and the commercial uses to 

 which it has been adapted. Its resistance to corrosion and strength at 

 high temperatures are perhaps the most useful properties. 



Nickel Brasses. — {Chemical and Metallurgical Engineering, Feb. 9, 

 1921, 24, No. G). A summary of the work of Guillet, published in 

 "Revue de Metallurgie " of 1913 and 1920, on the important role 

 played by nickel in the manufacture of low-copper ternary brasses. 



Chemical Properties and Metallography of Nickel.— Paul D. 



Merica {Chemical and Metallurgical Engineering, February 2, 1921, 24, 

 No. 5). Data on solubility and magnetic transformation of pure nickel. 

 Notes are also given on the effect of the common impurities such as 

 carbon, oxygen, manganese, sulphur, cobalt, iron and silicon upon 

 various physical properties. 



Arc-fused Steel. — Henry S. Rawdon, Ed. C. Groesbeck and 

 Louis Jordan {Chemical and Metallurgiccd Engineering, October G, 

 1920, 23, No. 14). Tests cut from blocks of arc-fused metal gave 

 mechanical properties like an inferior, porous casting, notably deficient 

 in ductility, and determined entirely by unsoundness in the structure. 

 Carbon, silicon and other elements are lost from the welding pencil 

 during depositiqji. 



Effect of Nitrogen on Steel.— 0. A. Knight and H. B. Northrup 

 {Ghemiccd and Metallurgiccd Engineering, December 8, 1920, 23, No. 23). 

 Work showing that at least five definite layers are produced on the 

 surface of low-carbon steel when it is exposed to ammonia at 650° C. 

 Excessive brittleuess in the outer zones responsible in part for gun 

 erosion. 



Plastic Crystals of Ammonium Nitrate. — W. N. Bond {Phil. 

 Mag., 41, No. 241). Part 11. of this communication should be of 

 interest to microscopists, for it is shown that in bent crystals, ground 

 and mounted, the extinction lines seen when the specimen is examined 



