22 



ISOMORPHISM AND THERMAL PROPERTIES OF FELDSPARS. 



Philadelphia Mint laboratory, while the copper was also from Eimer & 

 Amend ("C. P. copper drops, cooled in hydrogen"). 



Careful analyses of samples of the cadmium, zinc and copper follow : 



* This figure is doubtless somewhat too high. 



It was not deemed necessary to make an analysis of the silver, as 

 we were assured that it contained no impurity which could be quanti- 

 tatively determined. 



The melting temperatures of cadmium and zinc are relatively low, 

 and those of silver and copper comparatively high on the gas scale, 

 with a long interval between, so that it sometimes becomes very 

 desirable to have an intermediate point. The two melting points 

 which are most conveniently located are aluminium and antimony. 

 Aluminium, on account of its low density, and perhaps because it 

 has been less successfully purified than the other metals, does not 

 give a sharp and satisfactory melting point. The melting point of 

 Kahlbaum's antimony, of which a recently published analysis is 

 reproduced here, serves this purpose excellently. It rarely solidifies 

 without considerable undercooling, but the point to which the tem- 

 perature rises after crystallization begins is sensibly identical with 

 the melting point. 



Antimony (Kahlbaum, Berlin). f 



Fe 0.012% 



004 



003 



Cu 

 Pb 



019% 



The C. P. antimony obtained from Eimer & Amend and from 

 Merck & Co., in a careful analysis, for which we are indebted to Dr. 



I Fritz Henz, Inaugural Dissertation, Zurich. Published Leipzig, 1903. 



