ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 675 



Metallography, etc. 



Aluminium-zinc Alloys.* — W. D. Bancroft has determined the 

 tensile strength of alloys prepared from aluminium and zinc, both of 

 high purity. The alloys were melted in artificial graphite crucibles, 

 and were cast at temperatures 50° C. above their melting points, in 

 graphite moulds. From to 4 p.c. aluminium the tensile strength 

 increases from about 4 to 11 tons per square inch, from 4 to 60 p.c. it in- 

 creases more gradually to 16 tons, and then decreases to about 6 tons 

 for pure aluminium. 



Aluminium-copper-tin Alloys. t — C. A. Edwards and J. H. Andrew 

 have amplified their work on this ternary system, J investigating the 

 constitution and determining the properties of numerous alloys. In 

 accordance with the method recommended by Shepherd and Upton, 

 metallographic examinations were relied upon for the location of the 

 boundary lines of the different phases. The original paper, with dia- 

 grams and photomicrographs, should be consulted for the details of the 

 constitution of the alloys. No ternary compound is deposited from the 

 liquid alloys, and no ternary eutectic is formed. An alloy containing 

 10 p.c. tin and 9 p.c. aluminium is a homogeneous solid solution at 

 000° and at 500° C, but at interjacent temperatures reactions occur in 

 it producing quite different structures showing two phases. The authors 

 suggest that at 900° C. the y copper-tin phase is in solution with the 

 ft phase, while at 500° C. it is the 8' in solution with (3. This implies 

 that the identity of a phase or constituent is not destroyed when in 

 solution. 



Copper-zinc Alloys. § — T. Turner and T. M. Murray have deter- 

 mined the changes of length of cast bars of numerous copper-zinc alloys 

 and of some pure metals when cooling from the solidifying temperature. 

 The extensometer used was an improved form of the instrument 

 previously employed for similar work. || The temperature of the bar 

 was taken during cooling by a thermoj unction ; cooling curves were 

 obtained in this way in addition to the volume-change curves. The 

 cold alloys were examined microscopically, and their hardness deter- 

 mined by the Shore scleroscope and the Brinell method. The pure 

 metals, after solidification, contracted in the mould at a uniformly 

 decreasing rate. Most of the brasses expand on solidification, the 

 maximum and minimum expansion corresponding respectively to the 

 greatest and least distances of the "solidus " from the "liquidus" curve 

 in the equilibrium diagram. There is a remarkably large expansion 

 with the alloy containing 14 - 76 p.c. copper. A maximum total shrink- 

 age, and a maximum hardness at 40 p.c. copper point to the existence of 

 Cu 2 Zn 3 , supported by microscopical and other evidence. 



* Trans. Amer. Brass Founders' Assoc, 1909, pp. 47-54, through Journ. Soc. 

 Chem. Ind., xxix. (1910) p. 159. 



+ Journ. Inst. Metals, ii. (1909) pp. 29-57 (32 figs.). 

 % See this Journal, 1910, p. 119. 

 § Journ. Inst. Metals, ii. (1909) pp. 98-150 (31 figs.). 

 || See this Journal, 1906, p. 743. 



