128 J. Scully — 0?i the Effects produced hy small quantities of [No. 2, 



ings being rapidly cooled. The remarks already made with reference 

 to fine silver alloyed with the same proportions of bismuth would apply 

 here almost exactly, that is to say, the bars were rolled out to a thickness 

 of 0"015 with somewhat ragged edges, so that, although ductility, 

 as thus tested, was impaired, it was only slightly so. With 6 per mille 

 of bismuth (fineness of metal on assay 983' 9) the edges cracked a little, 

 and, after annealing and rolling out, the strap had decidedly jagged 

 edges and was split for some distance at one end. The bars containing 

 4, 5 and 6 per mille of bismuth were now remelted and allowed to cool 

 slowly and completely in the mould. They were all found to be highly 

 brittle, broke easily under the hammer — the fracture being granular 

 and not crystalline — and on being rolled they cracked badly, all over 

 the surface and at the edges, on the 1st or 2nd pinch ; in one 

 case the bar broke in two on the 2nd pinch. That these very different 

 results were again solely due to the manner of cooling was proved by 

 remelting and rapidly cooling the castings, when the same metal proved 

 comparatively ductile, as first stated. 



Silver of the Indian standard of 916*6 per mille (the rest being 

 copper) to which 2 per mille of bismuth was added, gave on lamination 

 straps with slightly jagged edges and proved to be red-short. With 4 per 

 mille of bismuth the bars showed a few surface cracks on being rolled, and 

 the resulting straps had decidedly jagged edges. Slow cooling of these 

 castings did not affect their ductility, thus showing a marked contrast 

 to what had been observed in the case of fine silver and the alloy con- 

 taining only 10 per mille of copper. When the amount of bismuth was 

 increased to 5 per mille, the copper present remaining at 83'4 per mille, 

 the bars were decidedly brittle and cracked readily on hammering — the 

 fracture being again granular, and not crystalline as in the case of fine 

 silver. On lamination both surface and edge cracks developed after 

 four pinches from the rolls, and in annealing one of these bars the 

 whole surface blistered considerably, no doubt owing to the temperature 

 having been carried a little too high. Standard silver with 10 per 

 mille of bismuth, reducing the fineness as ascertained by assay to 

 906*6, was very brittle, the bars breaking easily under the hammer, and 

 on the 4th pinch from the rolls splitting and cracking all over the sur- 

 face. In the course of these latter experiments it was ascertained that 

 with from 83*5 to 70 per mille of copper present slow or rapid cooling 

 of silver alloys containing bismuth made no appreciable difference in 

 their ductility. 



The foregoing experiments having furnished some information as 

 to the amount of bismuth that might be expected to injure our coinage 

 alloy, it was now decided to test that point practically, by operating on 



