162 Sir W. C. Koberts-Austen and Dr. T. K. Eose. [Oct. 22, 



are given in the following table, and have been plotted in fig. 1, in 

 which the abscissae are atomic proportions of the metals in the alloys. 

 The freezing point of gold was taken as 1064°. 



Fig. 1. 



C 



//oo c 



1050 



% 



tooo 



95d 



900 



IO 



20 



JO 40 50 60 70 



Atoms of SiLver per cent. 

 Percentage of gold present in alloy. 



30 



90 



too 



By weight. 



In atoms. 



Freezing point. 



ioo 



100 



1064° 



80-99 



70-25 



1061 



64-60 



49-97 



1061 



54-80 



39-89 



1046 



43-98 



30-07 



1044 



31-71 



20-28 



1028 



17-23 



10-23 



1001 



The following points had been observed by Heycock and Neville* : — 



2-26 1-25 962° 



0-91 0-50 961 



960 



It will be seen that Gautier's conclusion is substantially confirmed, 

 but it was observed, as one of us had previously pointed out,f that the 

 first additions of silver did not depress the freezing point of gold. So 

 far does this property extend that even the alloy containing 50 atoms 

 of gold to 50 of silver, or 64-6 per cent, of gold by weight, solidifies 

 at 1061°, which is only 3° below the freezing point of pure gold. 

 With further additions of silver there is a steady acceleration in the 

 rate of lowering of the point of solidification, so that the freezing-point 

 curve of the series has no double flexure, unless one is indicated near 

 the silver end of the curve by Heycock and Neville's results. 

 * ' Phil. Trans.,' A, vol. 189 (1897), p. 69. 



f Eoberts- Austen, ' Proc. Inst. Mechanical Engineers,' 1891, p. 564. 



