. Transactions. Cosmos (1912j 54, (546-648) analyzed mercury that had been saturated by twoweeks contact in a thermostat with tihngs of silver-tin alloys, ranging by 10-per cent,steps from one pure metal to the other. _ They found that at 25° C. the mercury dis-solved but per cent, silver and per cent, tin, and that these saturation valueswere independent of the composition of the alloy. At 63° C, about per cent, per cent., respectively, were dissolved. Even the most thorough amalgamationof dental office practice is hardly likely to bring about complete saturation. ARTHU
. Transactions. Cosmos (1912j 54, (546-648) analyzed mercury that had been saturated by twoweeks contact in a thermostat with tihngs of silver-tin alloys, ranging by 10-per cent,steps from one pure metal to the other. _ They found that at 25° C. the mercury dis-solved but per cent, silver and per cent, tin, and that these saturation valueswere independent of the composition of the alloy. At 63° C, about per cent, per cent., respectively, were dissolved. Even the most thorough amalgamationof dental office practice is hardly likely to bring about complete saturation. ARTHUR W. GRAY 669 Influence oi-^ Temperature Fig. 12 represents the results of crushing 63 similar C3linders of ahigh-grade dental amalgam at temperatures fairly uniformly distributed 50 O-40 c .30 1 L.^ 1 iJ 1 —II— 1 1 .. ^ ^-1^ i 1— h^ 1 r e Kg141 400 Q. 1131 S. 1 2 Trituration Time Minutes Fig. 10.—Changes in mercury content produced by varying devoted totriturating mix of alloy and mercury. 4000. I4IQ. 3000 1 2 Trituration Time 8 Minutes Fig. 11.—Gain in crushing strength produced by increasing trituration TIME. over the entire range from below 25° C. to over 95° C. Each cjlinder wasprepared bj^ incorporating the same mass of allo}^ filings with times 670 METALLOGRAPHIC PHENOMENA OBSERVED IN AMALGAMS this mass of mercuiy. After triturating for 4 iiiiii., the resulting smooth,plastic amalgam was packed under a load of 400 kg. maintained for 8min. This produced a cylinder mm. in diameter by , 40 per cent, of its mass being mercur3^ All the cylinders preparedin this way were immediately placed in an incubator kept at ° C. 4ooo 3ooo u o looo 05 ? X « \ • k \ ^^ 1 \* ^ • 4 V. 60° 80° 100° 20° 40° Temperature Centigrade Fig. 12.—Effect of temperature on crushing strength. Transitionregion shown by the rapid fall in strength between 70° and 80° is confirmedBY Figs. 13 and 14. (body temperature), where they remained f
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
