Thus if 4 atoms of bismuth, 1 of tin and 1 of lead be fused together, the compound melts in boiling water or below 212°. It is equally the case if 3 atoms bismuth, 1 of tin and 1 of lead, are fused together. The double alloy next to those above mentioned in regard to easy fusion is that of 2 atoms tin, and 1 bismuth. It fuses at 320°. This alloy, united to the one of 2 atoms bismuth and 1 lead, gives a compound of 3 atoms bismuth, 2 tin and 1 lead, which fuses very nearly at the same temperature as the above triple alloys. In reference to weights, the above proportions for the most fusible metals will nearly be, Bismuth 14 parts -- Lead 5 -- tin 3 ------- 10 ----- -- ---- 5 ------ 3 ------- 5 ----- -- ---- 2½ ------ 3 Most of the elementary books have given the proportions of 8 bismuth, 5 lead and 3 tin; or 5 bismuth 2 lead and 3 tin, which nearly agree with some of the above, and give an alloy fusing below 212°. Wishing to investigate this subject more fully, and it being obvious from the preceding facts that there are only two proportions of tin and lead to be united with bismuth, to produce the desired effect, namely, either 1 atom of tin with 1 of lead, or 2 atoms of tin with 1 of lead, I proceeded as follows: 1 atom tin (52) + 1 atom lead (90) + 1 atom bismuth (62), were fused together; the fusing point was 270°. The alloy was flexible to a certain degree; and the fracture very small grained. To this alloy 31 grains of bismuth were added successively till it was evident the alloy was growing less fusible; the results were as follows: 1 atom tin + 1 lead + 1 bismuth; fuses at 270° 1 -------- + 1 ---- + 1½ ------ -------- 235° 1 -------- + 1 ---- + 2 ------ -------- 205° 1 -------- + 1 ---- + 2½ ------ -------- 200° 1 -------- + 1 ---- + 3 ------ -------- 197° 1 -------- + 1 ---- + 3½ ------ -------- 200° 1 -------- + 1 ---- + 4 ------ -------- 220° 1 -------- + 1 ---- + 4½ ------ -------- 205° semi fluid. 1 -------- + 1 ---- + 5 ------ -------- 240° semi fluid. but it retains a little fluidity down to nearly 200° From this it appears that 3 parts by weight of tin, 5 of lead, and any proportion of bismuth from 7 to 14 will produce an alloy fusing below 212°; but of these the best is 10 or 11 parts. Again, 2 atoms of tin were combined with 1 of lead and 3 of bismuth, by gradually adding one half of the tin. The several alloys fused without any material difference at or below 200°. A further addition of tin impaired the property as in the above case with bismuth. I did not think it important to mix 2 atoms of tin and 1 of lead with any other proportion than 3 atoms of bismuth. APPENDIX.