712 SUMMARY OF CURRENT RESEARCHES RELATING TO 



temperature, and therefore tends to concentrate the transformation. The 

 ordinary temperature of transformation, 150° C, is that at which the 

 solid solution saturated at the eutectic temperature, containing about 

 18 p.c. tin, begins to deposit tin. 



Formation of Solid Metallic Solutions by Diffusion in the Solid 

 State.* — Gr. Brum' and D. Meneghini have heated a nickel wire, electro- 

 l\ tically coated with copper, at 1000° C. in hydrogen, measuring the 

 electrical resistance from time to time during the heating. The resist- 

 ance, originally - 026 ohm, ultimately rose to 0*21 ohm. The wire 

 showed no signs of fusion, and the authors conclude that a solid solution 

 of nickel and copper was formed by diffusion in the solid state. 



Alloys of Silicon with Metals.f— R. Frilley has prepared, in an 

 electric arc furnace, numerous binary alloys of silicon with manganese, 

 chromium, nickel, iron, tungsten, copper, aluminium, calcium, barium, 

 and strontium. The density of each alloy was accurately determined, 

 and the curves, showing the relation for each system between density and 

 composition, are held to indicate by inflexions or other peculiarities the 

 presence and composition of the definite compounds occurring in the 

 system. A list of the compounds found is too lengthy for reproduction. 

 The author points out the simplicity and accuracy of the density method 

 of investigating alloys. A comparison of the results obtained by apply- 

 ing the method to the copper-aluminium and cadmium-mercury systems, 

 with the equilibrium diagrams obtained by the better-known thermal 

 and microscopical methods, demonstrates the reliability of the density 

 method for indicating the compounds. For each silicon-metal system 

 the density results are given in the form of a specific gravity curve, a 

 specific volume curve, and a molecular volume curve, abscissas repre- 

 senting in each case the percentage composition. Some information 

 about the properties of the alloys is given. 



Extraction of Gases from Copper.f — M. Guichard has made measure- 

 ments and analyses of the gases extracted from copper by heating in a 

 vacuum. The gas is quickly evolved from the superficial layer of the 

 specimen, but the gas contained by the deeper layers diffuses very slowly 

 to the outer layer, where it is evolved. By chemical methods, involving 

 the conversion of the copper into iodide or oxide, much greater quantities 

 of occluded gases were extracted. The extraction of the total gas content 

 of copper by heating in a vacuum accordingly presents great difficulties. 



Crystallization of White Cast Iron.§ — C. Benedicks has examined 

 microscopically a hyper-eutectic cast iron containing 4-36 p.c. carbon 

 and 1 p.c. manganese. Three faces of the specimen, approximately at 

 right angles to each other, were polished and etched. The eutectic was 

 found -to exist as "colonies," resembling homogeneous crystals. In 

 some cases the eutectic exhibited spherical surfaces. The solidification 

 of white iron appears to proceed in a discontinuous or oscillatory manner. 



* Atti R. Accad. Lincei, xx. (1911) pp. 671-4, through Journ. Oheni. Soc, c. 

 (1911) p. 703. 



t Rev. M6tallurgie, viii. (1911) pp. 457-559 (39 figs.). 



t Comptea Rendus, cliii. (1911) pp. 104-7, 272-5. 



§ Int. Zeitschr. Metallographie, i. (1911) pp. 184-91 (14 figs.). 



