C. A. Wolle on a supposed Hercynite. 351 
for a considerable time, thereby evolving SO,. After a perfect 
ion the mass when cold was dissolved in water made slightly 
acid with HCl, and from this solution the Al,O, and Fe,O 
precipitated with NH,O and finally separated by KO, an 
treated as usual. The Fe,O, after being incinerated weighed 
‘2364 gram,=29°40 per cent, and the Al,O, weighed 4885 
gram, =60°79 per cent. 
The MgO in the filtrate from the first precipitate of Al,O, and 
Fe,O, was Prenetes: as phosphate with phosphate of soda, 
and weighed, after incineration, 2863 grm. =‘1032 grm. 
=12°84 per cent. The results of the analysis therefore yield— 
Fe,0, = 29-40 per cent. 
MgO = 1284 * 
AJ,O, = 6079 “ 
103-08 
The iron does not all exist as FeO, for such constitution would 
give the oxygen ratio of RO: R,O, as 1: 2557 instead of 
he Ties and insolubility in acids of this mine 
aV3: c 2 . 
would give the oxygen ratio 1: 3 will yield the following per- 
centage composition : 
a # Fe Mg 
6079 626 2174 12.84 = 10068 
and calculating from the formula— 
(¢Mg+4¥e) + )7$Al+ ay¥Fe), 
we obtain the following percentage composition, which agrees 
Well with the above analysis: 
Al Ec) Fe Mg 
6045 404 2295 1286 = 100 
An analysis of a spinel from Tunaberg, by Erdman, gave the 
following results :— 
Mg 13°03 Fe 23-46 3 62°95 = 99°44. es 
From the above analyses and remarks, it will therefore 
Seen that the mineral is yy magnesia iron spinel, with part of the 
the Al,O, replaced by Fe,0,, and it may be regarded as inter- 
mediate between Hercynite and Ceylonite, 
Sept. 1869, 
