418 ,i m \i:V 01 i URRENT RESEARCHES RELATING TO 



Metallography as an Aid to the Brassfounder.* — II. S. Primrose, 

 discussing the use of microscopical examination for controlling t he quality 



brass and bronze castings, points oul the importance of casting tem- 

 perature in the case of gun-metal castings. 



Shrinkage of the Antimony-lead Alloys.f — D. Ewen and T. Turner 

 have determined the changes in length taking place in east liars in cooling 

 from the solidification temperature, for antimony-lead and aluminium- 

 zinc alloys. Time and temperature observations were made simulta- 

 aeously with the length measurements. The microstructure and hardness 

 of the cold bars were investigated. In tin/ antimony-lead system, where 

 no solid solutions exist, the extensometer curves give results apparently 

 having no relation to the equilibrium diagram, except as indicating an 

 expansion due ti> the solidification of the eutectic. In the aluminium- 

 zinc system, which contains solid solutions, the expansion curve closely 

 follows t lie Iiquidus curve from <> to 50 p.c. aluminium. A general theory 

 relating expansion in alloys to range of temperature during solidification 

 cannol yet lie propounded. 



Effect of Silver, Bismuth and Aluminium upon Copper.:!: — F. John- 

 son has determined the effect upon the properties of copper, containing 

 small quantities of oxygen and arsenic, of additions of silver, bismuth 

 and aluminium. The ingots were hot-rolled to bars ; tensile and bending 

 tests were made, and the microstructure was studied. Hydrofluoric acid 

 was used as an etching re-agent for some of the specimens containing 

 bismuth. 



Occluded Gases in Copper Alloys.§ — G. Guillemin and B. Pelachanal 

 have heated twelve different specimens of brass, bronze and tin in a 

 vacuum at 1100 or 1000° C. The extracted gases were analysed, and 

 were found to consist chiefly of hydrogen in the sound specimens, while 

 in spongy castings notable amounts of carbon monoxide and dioxide were 

 found in addition to the hydrogen. Phosphor bronzes yielded little gas. 



Influence of Sulphur on the Iron-carbon System. || — T. Liesching 

 lias taken cooling curves of fifty melts containing 0*08 to 4 '78 p.c. 

 carbon, 01 to I'll p.c. sulphur, and has microscopically examined 

 the Bolid alloys. The microsections were etched by successive immersion 

 in an amyl-alcohol solution of picric acid, an amyl-alcohol solution of 

 nit rie acid, and a hot solution of sodium hydrate. The sulphide was 

 coloured brown in preparations thus obtained. The temperatures of 



mencing solidification and of eutectic solidification are lowered by 

 addition of sulphur; the temperature of pearlite formation (Ar x ) is 

 unaffected. Melts containing more than 2 p.c. sulphur and a high car- 

 bon contenl separate into two layers, the upper layer being rich in sulphur 

 and poor in carbon, the lower poor in sulphur and rich in carbon. 



* Jouru. Inst, Metals, iv. (1910) pp. 248-64 (16 figs.). 

 t T.>m. cit., pp. 128-62 (29 figs.). 

 : Tom. cit., pp. 1G3-234 (24 figs.). 

 § Rev. Metallurgie, viii. (1911) pp. 1-6 (6 figs.), 

 tallurgie, vii. (1910) pp. 565-71 (19 figs.). 



