356 On the Chemical Constitution of Warwickite. 
If the volatile matter be regarded as not essential to the com- 
‘ position of the mineral, we have as the ratio of the oxygen of 
the titanic acid to that of the hases, 14-82 : 22-66, or very nearly 
: 3, which leads to the formula Ti O,, 3(Mg O, Fe O), or, Ti ty O, 
(M, j in the notation of Gerhardt, or a trititanate of magnesia in 
which a small portion of the base is replaced by protoxyd of iron. 
This interesting mineral adds another to the small number of 
simple titanates already known, and pertains to a different chemi- 
cal type from either Perowskite or Polymignite. The Enceladite 
which I formerly proposed as a new species, is undoubtedly 
nothing moresthan Warwickite, altered by a process similar to 
that which has converted the associated spinels into steatite, the 
introduction of silica and water. 
It might be a question whether the alumina were introduced 
‘placed in part the magnesia of the larger crystals, which also 
contain a larger proportion of iron. It is however to be remarked 
in the first place that as far as examined, steatitic pseudomorphs 
do not appear to contain alumina, unless it has been an original 
ingredient in the composition of the mineral; and secondly, that 
excluding the silica and awe the ratio between the oxygen 0 of 
the titanic acid, and that of the magnesia, protoxyd of iron and 
alumina in the Enceladite is very nearly 2: 3, as in the War- ae 
wickite. I am therefore inclined to regard, the alumina as AIS 
(Gerhardt) as replacing in part the magnesia of the larger crystals. pee 
nalysis of some of these in an Y unaltered condition would i 
be very desirable to settle the question. 
I avail myself of this occasion to correct an error which occurs 
in the “ Annual Report of the Progress of Chemistry” for 1847-48, 
by Profs. Liebig and Kopp. In citing my description of the 
Enceladite, they state that I regard the mineral as an altered ti- 
tanic iron.* The compiler has however failed to apprehend my 
meaning ; in. suggesting its ae metamorphic origin, I re- 
marked that the form of the crystal was inconsistent with the 
idea that it could be derived ele a titanic iron by the introduc- 
tion of a silicate of magnesia and water.t I had not at that 
time the present results to guide me in forming a notion of the 
real nature of the 3 i a action.{ 
"aI C. E., March 12th, 185 
i it 
about the same thine by Echporor nt support of his view 
ony ss —— of Hitteroé. SAanalen der F hysik 
