130 On the Chemical Composition of Wernerite, 
Magnesia, . 
Potash, : 
Soda, : : 
Volatile substances, 
0:24 80°26 
0:97 
a 6°88 
0°33 0°33 
The quantities of oxygen are— 
Silica, 2 ¥ 94°32 
Alumina, . ' 12°21 . 
Peroxide of iron, 0:42 } 12°63 
Lime, 4:90 
Potash, 0-10 
Volatile substances 1:76 
0:2 
0:97 
6°88 
0:33 
100-00 
The composition of this mineral is therefore identical with 
that of the compact variety (4) from the same place. 
For the purpose of a general comparison of the composi- 
tion of the above varieties of scapolite, the author has tabu- 
lated the oxygen ratios obtained from the analytical results, 
together with the deviations from that corresponding to the 
formula RO, R,O,, Si O, and the densities :— 
siO, R, 0, 
Blue scapolite rae 
‘Malie), \ 4 :1-84 
White do. do. 4 : 1°86 
Glaucolite (Baikal), 4 : 2°16 
Compact scapolite Le. 
(Arendal), } + See 
Prismatic scapolite, 4 : 2:07 
Nuttalite, 4 : 2°03 
‘ ee ei 
It is hence evident, that the oxygen ratios corresponding — 
Differences. Densities. 
RO’ R,O, RO 
: 0:93 — 0°16 — 0:07 2-763 
: 1:09 — 0:14 + 0:09 2°658 
: 0-48 + 0:16 — 0:02 2-666 
: 1:19:54 0:12 + O89 2761 
: 1:13 +.0°07. + O18 2°697 
: 1:20 +. 0°03. 4+. O80. ..2°746 
: 1:17 + 0°26 + O17 2:'788 
to the composition of varieties of scapolite, differ as much 
from that of the formula (RO),, 2 SiO, + 2 R, O,, viz.,— 
1: 2:4, as Rammelsberg found it to be the case in the va- 
rieties of ekebergite. The differences have mostly a posi- 
tive value ; the proportion of bases is somewhat greater than 
that corresponding to the formula. Rammelsberg found this. 
to be the case with regard to the bases R, O,, while the pro- 
