. 
- 
f 
Analysis of Fowlerite. 419 
_ of confirmation. The only peculiarity in the analysis consisted 
I separating alumina, zinc, manganese and iron, by sulphid 
ammonium, and after redissolving the sulphids, passing their 
heated solution into a boiling solution of potassa, whereby the 
alumina and zinc were held in solution and the other two pre- 
cipitated. The zinc was separated from the alumina by passin 
sulphohydric acid through the potassa solution, whereby sulphide 
of zinc was precipitated. The iron and manganese were sepa- 
rated by carbonate of baryta. The following are the results of 
the analysis. 
Found. Corrected result. Calculated result. 
Silica, - - - 44-50 : : 
Protoyxd of manganese, 25°37 25°370 25:°370 
¥ ‘chron, == 11-00 11-002 11-266 
Oxyd of zinc, - AV5 4-150 4-250 
i - - 9°66 9-660 9-893 
Magnesia, - \ 627 5268 5395 
Alumina, - - 0-67 — — 
Potassa, eee. 0-60 Feldspar 3-556 — 
101-22 101203 100-000 
Since all the bases are protoxyds, and the amount of alumina 
is very small, it either acts with the silica, or forms a part of a 
foreign silicate. Because the 0°6 potassa requires 0°653 alumina 
to make feldspar, i. e., the amount found by the analysis, and be- 
cause potassa does not belong to the isomorphic bases in the min- 
eral, it is most probable that both of these bodies belong to a little 
feldspar which is accidentally present. Calculating them as feld- 
spar, they abstract 2°30 silica from the amount found, and give 
the above corrected result. 'The calculated result, omitting the 
feldspar, is given in the third column. The proportion of pro- 
toxyd bases to silica in the calculated result, is 1°85: 1 or 11:6, 
and even if the original result, as given in the first column, be 
adopted, the proportion is 1-76: 1 or 7:4. Neither of these satis- 
fies the formula adopted for Rhodonite, which is 3:2. Fowlerite 
is therefore either a peculiar silicate, not Rhodonite, or a mix- 
ture of Rhodonite and other silicates of manganese. Its formula 
very nearly satisfies the assumption of its being a half silicate, 
2RO, SiOs. If Rhodonite be separated from it, the formula is 
3RO, 28i02+4(2RO, SiO;). From my analysis, then, I should 
infer either, that the formula adopted for Rhodonite is incorrect, 
or that Fowlerite is a distinct species. 
