48 . Whitney's Description of Ferrotitanite. 
The use of fluohydrie acid in the analysis of. titaniferous 
silicates, is attended with only one disadvantage, namely, that 
it does not allow of the direct determination of the silica ; in 
other respects it would have decided advantages over any 
other method. 
The ratio of the oxygen of Fe : Ca: Ti: Si, being 
6.47 : 8.52 : 8.81 : 13.33, which may be taken at 
3: 4: 4 : 6, the formula will be 
(Ca? Si + Fe Si) + Ca Ti? 
This formula requires 
Silica EROS. 1b 
Oxide of iron 21.92 x 
Lime 30.80 
Titanic acid 21.96 
99.98 
It will be seen that the two first terms of the formula are 
the formula of the lime-iron garnet, which occurs associated 
with the ferrotitanite, the latter being a combination of one 
atom of garnet with one atom of bititanate of lime. Its 
analogy with sphene, or titanite, will at once be recognized 
and hence the name ferrotitanite, to indicate a mineral allied 
to titanite, and containing, in addition, oxide of iron. 
Rose, from his researches on the peni gave for this min- 
eral the formula 
Ca? Si + Tis Si, 
which Berzelius modified thus, 
2 Ca... Si. +. Ca. Tid, 
on the ground that the lime would bea so much stronger base 
than the titanic acid, if this latter should be considered a base, 
that a basic salt of the lime would necessarily appropriate a 
sufficient quantity of the silica to become saturated, and, if a 
portion remained over, it would combine with the titanic acid. 
This view of the case seems confirmed by the results of the 
analysis of the ferrotitanite. 
