(^‘ Crystallimiion of Epidote of Glauber-salt 31 S 
w 
compositions in which they join parallel to the face of — (T), 
The preceding observations will suffice for the proposed compa- 
rison of its series of crystallisation with that of Glauber-salt. 
The same letters which have been employed in marking the 
faces of crystallisation of Epidote, are made use of also in Glau- 
bei-salt. Figs. 5. and 8., for those which are analogous to the 
forms. It is impossible not to be struck with the almost en- 
tire coincidence of the relations among the simple forms, al- 
though the absolute measures of the angles are very , different 
Thus, 
In both Species. 
P 
^ “ 2 
In Epidote. 
ci: 70° 33' 
In Glauber-salt. 
= 93° 12' 
p 
■“ 2 
11 
0 
0 
= 81° 10' 
r 
Pr 
- 2 
= 63° 43' 
= 49 ° 50' 
T 
0 
Pr 
" 2 
= 64° 36' 
== 72° 15' 
d 
(P)" 
“ 2 
= 96° 15' 
= 112° 27' 
0 
= (Pr -h 00 f 
00 
0 
CO 
CO 
il 
= 86° 31' 
y 
= PF— 1 
= 103° 30' 
= 118° 12'. 
The limits P — go (0? P i’ + go (J/), and P r -}- go (P), 
occur in both. The inclination of the axis, = 0° 33' in Epi- 
dote, rr 14° 41' in Glauber-salt, takes place in a plane passing 
through the axis and the long diagonal. The angles of P, the 
fundamental pyramid itself, are : 
{ 70 °^!} ’ 151° 3'; 117“ 33'; 
140° 23'; 105° 51'. 
In Epidote =: ^ 
In Glauber-salt = ^ Jq' ’ 
The ratio of the lines a:b:c: d = 105 : 216.3 : 66.6 : 1 in 
Epidote, is n 3.816 : 7.005 : 3.188 : 1 in Glauber-salt. 
& .. Pr-pl 
The faces of — 
(t;) and of 
(w) in the 
2 ^ ^ 2 
latter, have not yet been observed in the former of these species. 
