42 



RESEARCHES ON THE 



chloride of Luteocobalt, chloride of Purpureocobalt, and a leek-green crystalline 

 body, which we have called provisionally Praseocobalt, but which we have not yet 

 carefully studied. 



The sulphate of Luteocobalt, like the chloride, has a fine wine-yellow color, and 

 crystallizes readily. The crystals belong to the right rhombic or trimetric system; 

 they are hemihedral and isomorphous with the chloride of Luteocobalt. According 

 to Prof. Dana's determinations, the more usual forms are represented in Figs. 11, 

 12, 13, 14. In Figs. 13 and 14 the sulphate is mixed with the chloride. 



O : f = 131° 19' q : i% = 88° 44' and 91° 16' 



: | = 118° 28' 15 : 15 (over 0) = 88° 22' 



: 35 = 101° 57' 

 : 15 = 134° 11' 



1:1= 113° 38' 

 0:1?= 146° 4' 

 IS: 15= 112° 8' (over 0) 

 35 : 35 = 127° 18' (adjacent) 



These forms in other symbols are 0, oo , 3-co , |, |, 1- <*>, (Fig. 11). 0, co , f , |, 

 -5o,3-Sb (Fig. 12). l-55,oo-|,3-c», (Fig. 13). 1 - 55, oo-f, 3-Sb , 1-co (Fig.14). 



a:b : c = 1,039 : 1 : 1,539. 



Fig. 12. 



Fig. 14. 



Figs. 15, 16, 17, are different in habit from the preceding, and do not agree 

 precisely in angles. The forms as lettered are referred to a different fundamental 

 form. Adopting the same fundamental form as in the above figures, the lettering 

 would be as follows : 



Lettering on figures, O t'2 12 | li I il -Ji \ J. 

 New lettering, O I § |2 35 ii il fS J2 £2. 



Angles obtained and calculated for Fig. 13 (putting the lettering on the figure in 

 brackets) : 



I : I («2 : »2) = 64° 28' and 115° 32' |2 : |2, {k : i) = 124° 3' (adjacent). 



O : | (0 : 12) = 120° 36' : 35 (0 : 15) = 119°. 



: §2 (0 : i) = 130° 59' i2 : »2 = 103° 10' (by calculation). 



Angles obtained and calculated for Figs. 14, 15: 



ii : i2 (I : I) = 103° 30' : f 2 (0 : J) = 150° 16'. 

 : f (0 : 12) = 120° 40' O : |2 (0 : |) = 120° 16'. 

 : §5 (0 : il) = 138° 6'. 



Fig. 18 has still a different habit. The occurring vertical prism, lettered I, gave 

 the angle (approximately) 101° 30', and the dome K has the angle 109° 36', giving 

 : U = 144° 48', near the angle in Figs. 11, 12. 



