433 



zinc, and 1*6 per cent, zinc in lead. And the same may be said of 

 the bismuth-zinc alloys when fused together in proportions greater 

 than those in which these metals dissolve in one another. 



IX. " On some Gold-Tin Alloys." By A. MATTHIESSEN, F.R.S., 

 and M. VON BOSE. Received August 28, 1861. 



It was observed in a former research* that the gold-tin alloys had 

 a great tendency to crystallize, and it was deduced from results then 

 obtained that some of them were chemical combinations. With a 

 view to ascertain whether these would crystallize out from the fused 

 metals, the following experiments were undertaken. 



The metals f were weighed out in the proper proportions, and 

 fused together in a crucible over a 4-Bunsen burner, a jet of gas 

 playing on the surface from above to prevent the oxidation of the tin. 

 When fused, the lamp was removed and the alloy allowed to cool 

 (the jet of gas still playing upon it) until the surface began to solidify, 

 when the liquid alloy was poured off from the crystals. Of course 

 the two metals were always stirred well, and cast several times before 

 the alloy was crystallized and analysed. 



When the metals were fused together in the proportion to form 

 AuSn 2 (62'9 per cent. Au) and AuSn 3 (53*1 percent. Au), no 

 crystals could be obtained in either case. When, however, more tin 

 was added, so as to make the alloy AuSn 4 (45 '9 per cent. Au), a 

 separation took place into a non- crystalline mass with a glassy frac- 

 ture and a very crystalline one : these may be easily separated from 

 each other by fusion, for the former has a much higher fusing-point 

 than the latter. The alloy containing 43' 5 per cent, gold behaved 

 in the same manner. The analyses of the different parts of these 

 alloys are given in the following Table. The gold was determined 

 by dissolving the alloy in nitro-hydrochloric acid, and precipitating 

 the gold from the strong hydrochloric acid solution with sulphite of 

 soda : 



* PhU. Trans. 1860. p. 170. 



t These were purified as described in the Phil. Trans. 1860, p. 177. 



