Messrs. F. C. Calvert and R. Johnson on Alloys. 24i7 



This alloy had not the lamellar appearance of zinc, but a cry- 

 stalline one, and was extremely hard and slightly fusible. We 

 thought, perhaps, that the bath was saturated with iron, which 

 had combined with, the zinc and had gradually deposited. We 

 accordingly took some of the melted alloy of zinc and tin in 

 various parts of the bath and examined them, but found only 

 traces of iron. It is certainly remarkable that the iron does not 

 remain diffused in the metallic bath, which is constantly kept in 

 a state of fusion, but combines in definite proportions with zinc, 

 forming a crystalhne compound, and that it deposits at a tem- 

 perature of at least 800° F. 



This fact induced us to examine the composition of the metaUie 

 bath, which being a very large one, gave us a good opportunity 

 of ascertaining a very interesting problem, viz. whether when we 

 employed definite proportions of zinc and tin to compose it, and 

 melted them together, the mass of the bath would have a uniform 

 composition, or would vary according to the depth. The bath 

 we used was 2i feet wide, 10 feet long, and 3| feet deep, and it 

 contained fourteen tons of melted zinc and tin. As this definite 

 compound of iron and zinc existed in large quantities at the 

 bottom of the metallic bath, in order to take our samples we 

 made a wrought iron tube, of two sections, with flanges the 

 entire length, joined together by means of screws, which brought 

 the parts of the tube into close contact. This tube, which had a 

 tap fitted on the upper end, being air-tight when closed, was 

 plunged into the melted metallic bath, and after having reached 

 a given depth, a little alloy was allowed to run in by slightly 

 opening the tap and then closing it. By this means we obtained 

 the following samples ; one at the top, one at from 21 to 24 

 inches deep, and one at the bottom, and we found these to have 

 the following composition : — 



100-00 10000 10000 



These numbers therefore clearly show that the metallic bath 

 of zinc and tin (for the lead may be considered as an impurity of 

 the zinc) had a different composition in its various pai-ts, and that 

 the chemical affinity was not powerful enough to maintain a uni- 

 form composition through the mass. It is also curious to observe 

 that the heaviest metals, viz. tin and lead, are in larger propor- 

 tions at the top of the bath than at the bottom. We shall not, 

 however, venture to give any explanation of this curious fact 

 until we have fui-ther data. 



