40 I’. Scheerer on Polymerous Isomorphism. 
Si Mg. Ga Fe H 
54. Rock Cork, Zillerthal, 57°20 22°85 13°39 4°37 2-48—=100:24 
75 
: 
5. Augite. 
f, 
55. See bt 
im) 
b 
oo 
S 
Ya) 
ol 
wo 
to 
1 
@ 
7 
bo 
wo 
pl 
5585 23 
5. Diopsidle Reichenstein, 5450 18°96 21:41 3-00 1-19, X1 1-10=100" 16, Rr. : 
Capes rae i Seg 1394: ~~ (2) 2986: 13°98: 10, (3) 29:00: 0-26 : 14:00:10], 
( 051: 14:37:10 " 
A ae leathet eile gave the composition of serpentine, — 
(Mg)* Si. q 
Ill. Tiatc nor Averric or Hornsienpic IN TYPE. 
Si Al Mg Fe 
Hydrotale, Presnitz, 67°81 «std 26°27 ELt 4:13= 99°38 
8:47 0°12 26°31 119 4:11=100°20 
< Sub-columnar, 67°95 0°24 25°54 1:59 414—= 99-46, Rr. 
Ox. ratios, (1) 35-21: :0-00: i107: 3:67. (2) 3555: : 0-06: 10°79 : 3-65, (8) 35:28: on: 10-57 : 3°68 
heerer’s ratios, 35°21 : 11-99 : 12:01 ik 
The first set ratios ehistipond i, 10< a 3 eae set, 
to 3:1, and the formula (R) Si. 
Conclusion.—The three general rations deduced by Scheerer 
for the species reviewed, are 9:4, 4:2, 3:1, Papa vs 
first to hornblende, RSiLR Ss Siz ; 2d to augite R* Si; 3d to 
From the alleged isomorphism of 1Mg and 3H, and of 28 pat 3a 
the following formulas are equivalents and the substances pre- | 
senting them should be isomorphous— 
(a) R* Si?, (6) R2 Sit +sH—oR Si+s3H, (c) RSi2+eH, (a) Sito. 
The minerals of the Augitic series whose composition is 
are compounds according to Scheerer, of (a) and (’) in different 
pee In a like manner, those of the Hornblendic series — 
nsidered as composed of the compounds RSi-+-R Siz (a), and 
sk S431! (#) in different proportions: and those of the Hydro- — 
tale series, of the compounds 28 Si (a), and RSi?+s%i (6) in different — 
proportions. His paper contains a table of the results, in whic 
the ratios of the two constituent portions are given, with the cal- 
culated and found results, in accordance with the ratios. We 
give a few examples, ps Nami to the paper for the complete — 
table. ) : 
1. Hornblendic pares Pes 
Oxygen ratios. ger honensy: a 
leme’ 2 
1. Colum. tale, St. Got, (11) (1-44 Al, 3.2171) | Cale. coe = Lats a 
2. Asbest. tale, ibid, (12) (10-83 Al, 2:84 H1) Sse Found * 20 : 18-46: oats 
(3°70 Ca) "20 : 18°42: 368 4 
” 0 Ja 
8. Tale, Tyrol, (1) (00H, 478) =f ro : 26 : 12:90 : 430 ee q 
21, Meerschaum, (21) (011 31, 957 H) Aide abet i : 
2%. = not ge Bape eye a 4 
