THE CONSTITUTION OF THE COPPER-TIN SERIES OF ALLOYS. G7 
hydrochloiic acid at 30° C., and that if air is excluded there is no solution of copper 
until all the excess of tin has been dissolved. The alloys disintegrate to a grey or 
black mud, which can be elutriated, leaving as a residue well-formed plates of t) or 
brilliant slender spearlike filaments of H. The washed H can be left for days in 
contact with strong cold hydrochloric acid without perceptible solution of either 
copper or tin. The -q is more attacked when the excess of tin has been removed, hut 
the attack is slight. 
The following are the results of some analyses, the composition being expressed in 
percentage weights of tin. In a few cases the copper was independently determined. 
Composition of rj. 
Alloy. 
Chilled at 
Percentage of 
Percentage of 
tin in >/. 
copper in rj. 
Sn .35. 
5.50 
39-09 
« 
Sn 35. 
550 
38-53 
61-20 
Sn 35. 
450 
39-15 
_ 
Sn 50. 
450 
39-10 
60-89 
Sn 50. 
450 
38-5 
_ 
Sn 50. 
450 
.38 - 77 
_ 
Sn 65. 
450 
41-71 
57-88 
Sn 65. 
450 
42-20 
_ 
% 
The above were early experiments, and no very great care was taken to maintain 
the temperature constant for a considerable time before chilling. Three ingots were 
however, treated after three days and nights in boiling sulphur vapour and then 
chilling. This preparation may be expected to ensure equilibrium between the solid 
and the liquid phases at 450°. The results are given below. 
f) Sulphur Boils 454°. 
Alloy. 
Sn 38. 
Sn 38. 
Sn 50. 
Sn 70. 
' 
Per cent, of tin in the r; 
38-73 
38-53 
39-73 
38-97 
In theory, whatever the percentage of the alloy, the composition of the solid phase 
at a particular temperature should be the same, and depend on the temperature only. 
But the character of the ingot at the moment of chilling seriously affects the 
possibility of extracting the desired body free from excess of tin, as, unless each plate 
of T) is separated from its neighbours, inclusions of tin may be unavoidable. Most of 
the discrepancies in the result are probably due to this cause, In view of the value 
K 2 
