T. Scheerer on Polymerous Isomorphism. 37 
Art. V.— Abstract of a Memoir on a Isomorphism, by 
TH. ScHEERER 
_ Tuts important paper covers nearly 100 pages in Poggendorff’s 
Annalen and presents a review of the subject of polymerous iso- 
morphism as developed by Scheerer, together with numerous 
new analyses of minerals, especially the magnesian. The two 
great points which the author considers as established are— 
1. That 1 atom of Mg may be replaced by 3 atoms of H, 
2. That 2 atoms of Si may be replaced by 3 of 41. 
We present our readers sec an abstract of his paper, citing in 
its illustration the new analyse 
I. AmpuHIBOLic age AND AMPHIBOLE. 
l. Foliated Tale. 
Si Al ry Ba Fe “Ni 
1, Fol.tale, Tyrol, a a4 19 142 020 473= 9992 G=2°69 
2. Tag ried 158 094 4-73= 99°82 
a ° «, vttre-Sogn, 0 b4 see tc. 8066 235 O81 4938== 9969 G—2°70 
+ wee vee 8062 2°38 0°29 49410014 
5. * * Réraas, 6108 004 12. g041 109 .... SOk= 9906 G—278 
B. See ce 62°03 0:03 ... 8062 157 032 5-04—= 99°61 
7. “ « Raubjerg, 61-85 018 ... 3161 118 036 51310026 G.=279 
8 ak Sy 6163 016 ... 31°37 120 089 5&1 9°88 
9. i < Tyrol, slaty, . 95 048 ... 31:26 148 035 529= 9976 G=2'76 
16 0-46 3117 140 039 531== 99°89 
10, 
by Potstone, Zablitz, iat O75 045 3017 205 028 571—= 9955 G—=280 
2. 0-31 O79 045 20°94 211 030 587= 99°77 
13. eet Canton- sia ii G=2-719 
Wallis, 0234 035 ... 3196 061 ..., 482=10008 G=2 
ae 
ey 
2 
62°55. 0- .. 82 
ay rs « Styria, ser, 032 ... 8202 065 .... peasy oo 
7 “ Fahlun, as 95 4:92 072 80:09 094 .... 60T= 996 
‘10 469 081 30°11 107 .... 607= ats 
18, Fol tale, white, Si. 
Got 
60-85 171... 8208 009 .... 495, Catrace=99°68 
= Col, fol. tale, « Mi ibes 144... 8076 020 ..:. 455, Ga 04210022 
“ 6215 101 ... 33:04 038 ...- $21,“ OO7= 99°86 
“The oxygen relation for the silica, protoxyds and water ee the 
first four of these analyses is 32-00 : 12°80 : 4-72=15: 6: 2. 
7 ratio ehaetat to the formula, according to the Berzelian 
method Sof or 3k Sit’ Si? + 2. 
which corresponds ihe Si 62-61, Mg 3251, FH 4:88=100. 
On the ground that st replace iMg, the ratio becomes 15 : 63= 
45: 20=9: 4, the oxygen ratio of hornblende. 
Scheerer also reviews the analyses 5 to 20 in which alumina 
exists, substituting 298i for #41, and brings out the same ratio 9: 4. 
- 9, Asbestiform Talc. . 
i ; Oa Fe 
#1. St. Gothard, Fis ae ae 370 O12  284—=99-93 
* Pogg. Ann, lxxxiv, p. 321. } Analysis made by Hm, Richter. 
