634 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Mg = 2. In general when several elements are added to a copper-zinc 

 alloy, each acts as if it were the only one. 



The Alloys of Antimony and Tin.* — F. E. Gallagher has inves- 

 tigated the freezing-point curve of the antimony-tin alloys, and finds 

 that, contrary to Keinders' conclusions, there are no compounds between 

 these two metals. The four solid phases are four sets of solid solutions. 

 Sixty-three alloys were made, of different compositions. They were 

 annealed at temperatures ranging from 218°-560° until equilibrium 

 was reached, and examined microscopically. The nature of the phases 

 was thus determined. The higher the temperature the more rapidly is 

 equilibrium attained. The etching reagent most frequently employed 

 was ferric chloride in alcoholic solution, which gave good preparations. 

 Some of the alloys rich in tin were etched by being made the anode first 

 in 1 p.c. nitric acid, then in an alkaline solution of sodium tartrate, the 

 latter removing the black deposit first formed. 



The Tensile Strength of Copper-Tin Alloys.f — E. S. Shepherd 

 and G-. B. Upton have studied the relationship between constitution and 

 physical properties of the bronzes. The complex freezing point curve 

 given is plotted from Heycock and Neville's data, modified by Shepherd 

 and Blough. The only chemical compound in the alloys containing 

 more than 50 p.c. copper is Cu 3 Sn. Solid solutions, denoted by 

 a, /?, y, and 8 (formerly thought to be Cu 4 Sn), are the other constituents. 

 By chill casting an alloy, annealing at a given temperature for as long a 

 time as may be necessary, then quenching, the structure and properties 

 normal at that temperature may be determined. Tensile tests were 

 made on the alloys (1) as cast, (2) heated for a week at 54 j° and 

 quenched in water, (3) heated for a week at 400° and furnace cooled, 



(4) heated to about 650° and quenched. The test pieces were cast 

 to shape in moulds of artificial graphite, which give an excellent 

 surface on the casting. Melting was carried out in an atmosphere of 

 illuminating gas. Occlusion of gas and oxidation are both much more 

 serious in the alloys with more than ',)<) p.c. copper than in those richer 

 in tin. A lengthy table of results of tests is given. Among the authors' 

 main conclusions are (1) the tensile strength of bronzes consisting of 

 pure a (87-100 p.c. Cu) is little affected by heat treatment, and increases 

 with increased tin content ; (2) bronzes with 74-87 p.c. copper are much 

 stronger if annealed above 510° than if annealed at a lower temperature ; 

 (3) prolonged annealing tends to make the crystalline structure coarser, 

 to decrease tensile strength and to increase ductility ; (4) the strongest 

 bronzes contain 78-81 p.c. copper and are mixtures of a and f3 crystals ; 



(5) the. stress strain diagram of a bronze tensile test piece shows no 

 falling off when the maximum stress is reached. Stress increases 

 steadily till the piece breaks. The stretch takes place along the whole 

 length of the test piece : there is no local contraction as with iron and 

 steel. 



The paper is of value not only for the facts brought to light but also 



* Journ. Phvs. Chem., x. (1906) pp. 93-8 (2 figs.), 

 t Op. cit., ix. (1905) pp. 441-76 (7 figs.). 



