ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 423 



Alloys of Aluminium and Silicon.* — C. E. Roberts has found by 

 thermal methods that the aluminium-silicon system is a simple eutecti- 

 ferous one ; this was confirmed microscopically. The silicon crystallized 

 in plates arranged in five- or six-rayed stars. 



Tungsten and Carbon.f — 0. Ruff and R. Wunsch have studied the 

 equilibrium of the tungsten-carbon system, and describe the microstructure 

 of a number of alloys prepared by melting in the electric furnace. When 

 more than 2 p.c. carbon was present, final polishing with any of the 

 usual polishing powders was ineffective owing to the great hardness of 

 the alloys ; these were polished on emery-paper only. The specimens 

 were etched with a mixture of nitric acid, hydrofluoric acid, and water, 

 and washed with water and sodium-hydrate solution to remove the 

 tungstic acid formed. Pure tungsten showed sharply-defined polyhedra. 

 With 0*12 p.c. carbon a eutectic was observed at the crystal boundaries. 

 As the carbon-content increased more eutectic appeared, and at 1 ' 43 p.c. 

 carbon the specimen consisted wholly of a eutectic of typical structure. 

 With more carbon massive carbide appeared, and at about 2 ' 1 p.c. the 

 alloy appeared to be wholly the carbide W 3 C. A second eutectic appeared 

 in alloys containing more carbon. The carbides found were W 3 C (melt- 

 ing point over 2700° C), WC, and probably W 2 C. In all, three eutectics 

 were observed, one of which appeared to be a metastable ternary eutectic. 



Copper-aluminium-nickel Alloys. J — A. A. Read and R. H. Greaves 

 have determined numerous properties of two series of alloys containing 

 5 and 10 p.c. of aluminium respectively. The nickel in each series 

 ranged from to 15 p.c. ; the remainder was copper. The authors find 

 that of the typical a and /3 constituents of the copper- aluminium alloys 

 the a certainly, and possibly the /?, will dissolve nickel without change 

 in appearance. In addition to these, two other constituents were met 

 with : A, in the 10 p.c. aluminium series, a greyish-blue constituent 

 which appears in the slowly-cooled metal at 5 p.c. nickel, but is 

 suppressed by quenching up to 7"5 p.c. nickel; with 10 p.c. and 

 more it forms primary crystals which are not removed by quenching. 

 B, in the 5 p.c. aluminium series : a constituent which in the slowly- 

 cooled metal first appears at 5 p.c. nickel, but which is suppressed by 

 quenching from 900° C. until the nickel exceeds 10 p.c. As a secondary 

 constituent this etches brown or bluish, but with 15 p.c. nickel what is 

 probably the same constituent forms primary dendritic crystals of a 

 clear blue colour, persisting after quenching. The authors incline to 

 the opinion that A is a nickel-aluminium compound, and B a copper- 

 nickel solid solution (probably containing aluminium). The etching 

 reagent generally used consisted of four parts of a solution of ferric 

 chloride in water (1 : 12), and one part of concentrated hydrochloric acid. 



Neumann LinesJ — In examining specimens of steel containing 

 0*05 to 0* 10 p.c. carbon, broken from a partially-rolled ingot, Matweieff 



* Journ. Chern. Soc, cv. (1914) pp. 1383-6 (5 figs.). 

 t Zeitschr. Anorg. Chem., lxxxv. (1914) pp. 292-328 (19 figs.). 

 % Journ Inst. Metals, xi. (19H, 1) pp. 169-213 (28 figs.). 

 § Rev. Metallurgie, xi. (1914) pp. 766-70 (7 figs.). 



