THE 



AMERICAN JOURNAL OF SCIENCE 



[FIFTH SERIES.] 



Art. XXXI. — The Silicates of Strontium and Barium; 

 by Pextti Eskola. 



Contents. 

 Introduction. 

 Methods of working 



The system SrO-Si0 2 



The system BaO-SiO. 



The system CaO.SiCX-SrO.SiO, 



The system CaO.Si0 2 -BaO.Si(5 2 



The properties of the glasses. 



Absence of diopside analogs. 



The strontium and barium feldspars. 

 Some general considerations regarding the relations of the alkaline earth 



compounds. 

 Summary. 



Introduction. 



Among the compounds of the alkaline earth metals 

 (calcium, strontium, and barium), the sulphates and 

 carbonates are common as minerals. In the case of the 

 silicates, however, we find those of calcium common, but 

 natural silicates of strontium and barium are few in 

 number, complicated in composition, and of rare occur- 

 rence. Considering the existence of isomorphous carbo- 

 nates, sulphates, and other compounds of these three ele- 

 ments, the non-occurrence of analogous silicates seems 

 striking and suggests experimental investigation to 

 answer the questions : Do strontium and barium under 

 experimental conditions form such compounds as are 

 known in the case of calcium? And, if they do, what are 

 their properties and relations to the calcium silicates? 



The calcium silicates which form from dry melts have 

 been studied, but very little is known about the strontium 

 and barium silicates. G. Stein 1 prepared some silicates 

 and determined their melting points as follows : SrSi0 3 , 

 1287°; BaSi0 3 , 1368.5°; Sr 2 Si0 4 , 1593°. R. Wallace 2 



1 G. Stein, Z. anorg. Chem., 55, 159, 1907. 



2 B. Wallace, Z. anorg. Chem., 63, 1, 1909. 



Am. Jour. Sci. — Fifth Series, Vol. IV, No. 23. — November, 1922. 



