

224 Dr. T. Kirke Kose. On certain [Feb. 9, 



of the 64-64-per-cent. alloy. There is here a long pasty sta 

 between the initial freezing point at 795, and a second point a 

 about 718. During this range of temperature the slowness of the 

 rate of cooling shows that solidification proceeds continuously and 

 that the part of the mass remaining liquid undergoes a continuous 

 change in composition. At the point when solidification is complete 

 there is a more pronounced evolution of heat at about the same tern 

 perature as that at which solidification begins in the alloys containin 

 from 52 58 per cent, of silver. The liquidus curve appears to show 

 a small cusp corresponding to the compound Ag 2 Cd, but it is probabl 

 that the compound Ag 2 Cd, which was detected by Heycock and Nevill 

 in solution in other metals* is partly or entirely dissociated whe 

 melted by itself. 



The alloy containing 58'62 per cent, of silver has two freezi 

 points at 720 and 695, separated by a pasty stage. The alloys con 

 taining from 52 55 per cent, of silver have freezing points at 720 

 and 420. The eutectic solidifying at 695 was not observed in th 

 cooling curves of these alloys, although there is little doubt that i 

 must exist, particularly in view of the micro-structure. The 50-per-cen 

 alloy solidifies at 694, and shows the eutectic point at 420. 



In the series containing from 50 60 per cent, of silver, the past 

 stage succeeding the initial freezing point gradually diminishes as th 

 percentage of silver is reduced, until in the 50-per-cent. alloy th 

 fall of temperature during solidification is only about 20, where 

 in the 75-per-cent. it is nearly 100. Nevertheless the freezin 

 point of the 50-per-cent. alloy is not so sharp as that of an undi 

 sociated compound, and after the temperature has fallen at a norm 

 rate to about 420 another considerable evolution of heat take 

 place, during which the temperature remains stationary. The point i 

 also observable in the cooling of the 52-, 55-, and 58-per-cent. alloy 

 becoming successively smaller and dying away at about the 60-per-cent 

 alloy. Prolonged heating at various temperatures between 420 an 

 695 had not any apparent effect on the specimens, which retained thei 

 shape when not subjected to stress. When, however, a cast bar wit 

 composition corresponding to the formula AgCd was subjected to 

 bending stress equal to 10 grammes per square millimetre of cr 

 section (about 14 Ibs. per square inch), it was found to become suddenl 

 plastic and to bend almost double without cracking at a temperatu 

 of 450. When chilled at temperatures somewhat above 420 the speci 

 mens assumed a red or lilac tint, especially after light polishing, whic 

 is not so markedly observable in the specimens chilled from beloi 

 420. The colour is observable in all the alloys containing from 4050 

 per cent, of silver, and is always confined to the surface layer. T 



"The Freezing-point of Triple Alloys," 'Chem. Soc. Trans.,' vol.65 (1894 

 p. 65. 



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