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ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 789 



Some Silver Alloys.* — -E. Pannam finds that copper may with 



advantage partially be replaced by nickel or cobalt in silver coins. 



Methods of preparation and the properties of the alloys obtained are 

 given. 



Some Chromium and Manganese Alloys, t — Gr. Hindrichs has 

 studied the binary alloys of chromium with tin, lead, copper, silver and 

 aluminium, and of manganese with aluminium and silver, by thermal 

 and microscopical methods. As chromium at its melting point, 1550° C, 

 is viscous, it was necessary to exceed this temperature considerably to 

 obtain homogeneous alloys. Owing to the great experimental difficulties, 

 the results are somewhat uncertain. The metals of each binary system 

 were found to be only partially miscible in the liquid and less so in the 

 solid state. The existence of the only compounds indicated, AlCr 3 , 

 AlgMn, and AlMn 3 , is doubtful. Tammann's rule that in a binary 

 system A B, A being the metal with the lower melting point, the solid 

 solubility of A in B is greater than that of B in A, is confirmed. It is 

 assumed that when the melting point of A is not appreciably lowered by 

 the addition of the more difficultly fusible metal B, B is insoluble in A 

 at that temperature. 



Electrical Conductivity of Magnesium-lead Alloys.} - - N. J. 

 Stepanow has worked out a method for the determination of the con- 

 ductivity of brittle and easily oxidised alloys. Magnesium and lead 

 were melted together in a graphite crucible under a layer of fused salts. 

 The alloy was drawn up into a previously heated hard glass tube lined 

 with soot. After cooling the tube was broken away. Rods, several 

 cm. long and 3-4 mm. diameter were thus obtained ; their conductivity 

 was measured at 25° and 100° C. The concentration-conductivity curve 

 agrees generally with the equilibrium diagram obtained by thermal and 

 microscopical methods. The existence of a solid solution, containing 

 up to 4 atomic p.c. lead, not detected by thermal or microscopical 

 methods, is indicated by the more sensitive electrical conductivity 

 method. The general relation between constitution and electrical 

 conductivity of alloys is discussed. 



Compounds of Nickel and Phosphorus.§ — N. Konstantinow has 

 determined the equilibrium diagram by thermal methods and examined 

 the alloys microscopically. The compounds Ni 3 P, Ni 5 P 2 , Ni 2 P, and one 

 still more rich in phosphorus, were found. Ni 5 P 2 exists in two modifica- 

 tions, a and ft. 



Lead-palladium Alloys. || — N. A. Puschin and N. P. Paschsky have 

 determined the electric potential of a number of alloys of lead with 

 palladium, against pure lead in a solution of lead nitrate. The form of 

 the potential curve indicates the existence of the compound Pb 2 Pd. 



* Gaz. chim. ital., xxxviii. (1908) pp. 349-51, through Journ. Soc. Chem. Ind. 

 xxvii. (1908) p. 813. 



t Zeitschr. Anorg. Chem., lix. (1908) pp. 414-49 (7 figs.). 



J Op. cit., lx. (1908) pp. 209-29 (3 figs.). 



§ Tom. cit., pp. 405-15 (11 figs.). 



|| Op. cit., lxii. (1909) pp. 360-3 (1 fig.). 



Dec. 15th 1909 3 a 



