with Potassium, Rubidium and Caesium. 



279 



monoclinic. Two different habits were observed ; long prisms, 

 developed in the direction of the clino axis were obtained 

 from hot solutions (fig. 1). The mother liquor from these, on 

 standing, gave shorter prisms in which the domes and clino- 

 pinacoids were wanting (fig. 2). 



m 



rri 



H^ 



The°forms observed were : 



m 110 

 p 111 



The axial ratio is as follows 



c 001 

 b 010 



d 031 



d:b :c -7047 ; 1 ; '5688 B = 100, N 001 = 59° 1' 16" 



The crystals gave fair reflections of the signal on the 

 goniometer. Measurements chosen as fundamental are indi- 

 cated by an asterisk. 







Calculated. 



Measured. 



TO a TO'" 



110 a 110 



62° 20' 



62° 26' 



BaS 



110 a 010 



58° 50' 



58° 50'* 



&aC 



010^001 



90° 



90° 



m a c 



110 a001 



63° 57' 



63° 57' * 



TO aJ) 



110 aIII 



60° 42' 



60° 42' * 



Ca|) 



001 a 111 



55° 21' 



55° 22' 



b~d 



1 a 03 1 



34° 20' 



34° 25' 



b *p 



010 A 111 



61° 42' 49" 



61° 42' 30 



to a to' 



110 ^ 110 



117° 40' 



117° 33' 



C a to' 



001 a110 



116° 3' 



116' 11' 



The crystals were too opaque for any optical examination. 



In conclusion the author wishes to express his indebtedness, 

 to Prof. H. L. Wells for valuable advice and for the interest 

 that he has taken in this work, and to Prof. S. L. Penfield 

 under whose direction the crystallography of these salts was 

 investigated. 



Sheffield Scientific School, January, 1893. 



