COMPLETE FREEZING-POINT CURVES OP BINARY ALLOYS. 
59 
falls increase with increasing concentration of tin in a way that suggests appropriation 
of the silver by the tin to form molecules of a compound. Near 50 atoms there is a 
point of inflexion, as in the lead curve. 
In neither curve is there an angle, until we come to the eutectic point, and from 
the absence of a well-marked intermediate summit it would appear that, if compounds 
of these metals with silver exist, they must be largely dissociated under the conditions 
of the experiment. The shape of the curves is, however, not inconsistent with the 
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In degrees Centigrade and atomic percentages. 
reality of such compounds. For example, Ag 4 Pb and Ag^Sn might well have a virtual 
summit below our curve at 20 atoms. But this view, though plausible, does not 
appear to us the most probable explanation of the curves ; we are disposed to attribute 
the marked change in the slope, which occurs near 30 atoms in the lead curve and 
later in the tin curve, to the aggregation of the atoms of these metals to larger 
molecules, or at all events to compare the state here to the flat part of the copper- 
I 2 
