ON GOLD-ALUMINIUM ALLOYS. 



207 



02 



/ 



\/ 



Curve 2. 



were second freezing points and not alternatives to those on the upper line, it is 

 certain that they are not a continuation of CD. We think that, as usual, these 

 second freezing points indicate the moment of solidification of the mother-substance 

 of the alloys between D and E. The composition of this mother-substance would 

 be given by the intersection D, and we should expect it to be an almost pure body. 

 In the case of the alloys near E, the amount of this mother-substance must l>e very 

 small, the heat produced by its freezing will be small, and therefore thermometer- 

 lag may lower the observed freezing point. This appears a reasonable explanation of 

 the downward curving of the line of second freezing points. The analyses of a 

 number of alloys in this region were conducted with special care, both the gold and 

 the aluminium being determined, and the atomic percentage calculated from their 



