( 615 ) 
Measured: Calculated: 
= (100): (010) =*89° 281 — 
c = (010): (001) =*70 17 
a = (001): (100) =*57 49 l / t — 
-==(001): (101) =*53 467, — 
l = (001): (Oil) =*65 45 — 
b = (112): (010) = 67 32 67° 36' 
b = (101): (010) = 68 47 68 477, 
q — (100): (Oil) = 67 29 67 26 
> = (001): (112) = 50 5 49 49 
- = (TOO) : (Toi) = 68 24 68 24 
n = (OOT) : (012) = 38 17 38 27 
= (012): (Oil) = 27 24 27 18 
b = (Oil) : (010) = 43 56 43 58 
o = (101): (112) = 52 35 52 47 
q = (112): (011)= 32 21 32 19 
b = (TlO) : (010) = 33 51 33 37 
i = (TlO) : (100) = 56 41 56 55 
• = (TlO) : (TOI) = 59 37 59 327, 
q = (TlO) : (OlT) = 35 10 35 217 , 
b = (Ul): (010) = 40 55 40 47 
: (llT) : (001) = 85 467, 85 487, 
to : a = (111): (100) = 74 28 74 307, 
to : q = (111): (OlT) = 38 5 38 37, 
The agreement between the observation and the calculation is an 
excellent one. 
Etching figures were not obtained. It may be, — looking at the 
acentric habit and plane-development of some of the forms, — that 
the symmetry is iiiclhio-pedial. The situation of the optical axial 
angle could not be determined. That of the optical main directions 
was such that the angle of extinction on {001} with the side (001): 
(101), was about 15°, but on {101} with the same side it amounted 
to about 12°, and that with an inclination which on {101} proceeds 
from the left in front to the right at the back, and on {001} from 
the right above to the left below. 
Here we are, consequently, also dealing with a polysulphide of 
the type Ba S, in which 7, of the sulphur has been replaced by 
