388 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Alloys of Cobalt.* — F. Ducelliez has determined the E.M.F. given 

 by binary alloys of cobalt with tin, antimony, bismuth, lead, and copper, 

 in a solution of cobalt sulphate, against cobalt, and also against the other 

 metal of the alloy. The compounds CoSn, CoSb, and CoSb 2 (?) are in- 

 dicated by the curves given. Compounds do not occur in the other 

 systems. 



Phosphides of Tin.t — P. Jolibois has made a microscopical and chemi- 

 cal examination of alloys of tin and phosphorus containing 1 to 40 p.c. 

 phosphorus. To obtain alloys containing more than 13 p.c. it was 

 necessary to heat tin and phosphorus together under pressure. The 

 mixtures were heated in sealed tubes at 020° C. Sn 4 P 3 , microscopically 

 observed as large hard needles in the alloys of lower phosphorus content, 

 and SnP 3 , were the only compounds found. The numerous compounds 

 of different formulae described by other workers do not exist. 



Phosphides of Nickel. £ — P. Jolibois, by dissolving nickel in a mix- 

 ture of tin with Sn 4 P 3 , has obtained the compound XiP 2 . When nickel 

 was dissolved in a mixture of Sn 4 P 3 with SnP 3 , the compound XiP 3 was 

 obtained. 



Effect of Compressing Mixtures of Metals. § — G. Tammann has 

 compressed mixtures of filings of two metals at a pressure of 5000 atmo- 

 spheres. The blocks obtained were examined microscopically, and their 

 behaviour on heating and their electrical conductivity investigated. It 

 was found that the formation of solid solutions or compounds could not 

 be brought about by pressure alone, for the blocks, immediately after 

 compression, consisted of the unchanged metals lying side by side. 

 Diffusion may go on in the cold, and is accelerated by raising the tem- 

 perature. In a compressed mixture of bismuth and thallium, mixed 

 crystals as a blue fringe between the metals can be seen after 5 hours at 

 120° C. The compound Bi 3 Tl 2 is formed at higher temperatures. 



Shrinkage of Metals and Alloys. || — F. Wiist has devised an accurate 

 method of determining the alteration in length of a cast bar as its tem- 

 perature falls from the solidifying point. An iron rod projected into 

 each end of the mould in which the bar was cast. These rods, co-axial 

 with the bar, were attached to small hydraulic cylinders, arranged in 

 such a manner that variation in length of the bar caused an alteration 

 in level of water in a capillary tube. From the time of casting of the 

 bar, observations of time, temperature and length were taken, and plotted 

 as time-temperature and time-length curves. The temperature-shrinkage 

 curve was obtained from these. A description of the microscopical struc- 

 ture of each casting is given. The shrinkage of lead, tin, zinc, aluminium, 

 copper, bismuth and antimony, and of a number of alloys of these metals 

 and of nickel, was determined. The shrinkage coefficients experimen- 

 tally obtained were found to differ notably from those calculated from 



* Comptes Rendus, el. (1910) pp. 98-101 (5 figs.). 



t Op. cit., cxlviii. (1909) pp. 636-8. J Op. cit., el. (1910) pp. 106-8. 



§ Zeitschr. Elektrochern., xv. (1909) pp. 447-50; through Journ. Cheui. Soc, 

 xcvi. (1909) p. 669. 



|| Metallurgie, vi. (1909) pp. 769-92 (82 figs.). 



