Day and Sosman— Melting Points of Minerals. 347 



Table I. — Continued. 



Substance 



Formula 



Transformation 



Eutectic between 

 2 solid solu- 

 tions of diop- 



side and | 4%sol j 4$S diops 



a-MgSi0 3 in •»'■■ "■■ ■" 



each other 



Eutectic between 

 diopside and 

 n-CaSi0 3 



Calcium alumi- 

 num silicate. 

 (Anorthite) 



95-% sol )62#diops. 

 J5o%sol. (38 M gi0; 



( 96#MgSiO s 



MgSiOs.CaSiOa 60 % 

 CaSiO s 40 % 



CaAl 2 Si 2 0„ or 

 CaSi0 3 .Al 2 Si0 6 



Bytownite 



Labradorite 



Andesine- 

 Labradorite 



Andesine 



Calcium 

 carbonate 



Borax 



Sodium 



chloride 

 Sodium 



sulphate 



Albitei 



Anorthite 5 

 Albitei 



Anorthite 2 

 Albitei 



Anorthite] 

 Albite 2 



Anorthite i 



CaCO s 

 Na 2 B 4 7 

 NaCl 

 Na 2 S0 4 



Melting 



Dissociation pres 

 sure = 1 atm. 



Melting 



Tem- 

 pera- 

 ture 



1385° 



1357 



1552 

 1550* 



Observer 



Allen & 

 White 



Day & 

 Allen 



Reference 



32 (1909) 



1,4 



(1905) 



Day & 

 Sosman 



151b ' Allen 

 1477+ 



1430f 



1375+1 " 



898 i Johnston 



41 ( Day & 

 ' 41 Allen 



800 

 884 



White 



46 (1910) 



1, 4 

 (1905) 



56 (1910) 



1,4 

 (1905) 



44 (1909) 



In the first column of Table I is the name of the compound 

 or mineral ; in the second, its molecular formula ; in the third, 

 the transformation or reaction which takes place at the tem- 

 perature given in the fourth column. The last two columns 

 contain the names of the observers, and the references. The 

 numbers are those in the published list of papers of this labo- 

 ratory, and the references are given at the end of this article. 



A number of melting and transition temperatures were onhy 

 approximately determined, on account of the sluggishness or 

 slow rate of the change. These are summarized in Table II. 



* Direct comparison with the nitrogen thermometer. 



f Being isomorphous mixtures of two compounds, these substances have 

 no melting point, but a melting interval. The temperature limits of this 

 interval are probably narrow, and its existence is entirely covered up by the 

 slowness with which these silicates reach equilibrium. See full discission 

 in paper 1 (pp. 60-69), or 4 (pp. 40-50). 



