MINERAL CONSTITUENTS OF METEORITES. 
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tube. Repetition of the experiment confirmed the delicacy of this test for the presence 
of titanium oxide, a test tried by which the precipitate from the Osbornite failed invari- 
ably to show any evidence of the presence of that oxide. Phosphorus was carefully 
looked for, but ammonium molybdate failed to give any trace of an indication of its 
presence. 
A negative test of the above kind would not afford sufficient ground for asserting the 
presence of zirconium ; on the other hand, it would seem a fair presumption that tita- 
nium at least is not present in Osbornite. That the metal to which these reactions are 
attributable is not zirconium, however, may be affirmed with some certainty. Mr. Sorby 
has made the pyrognostic characters of this element a special study ; and I gave that 
gentleman rather more than half of the minute amount I possessed of the precipitated 
oxide. 
He examined it in a microscopic borax bead, and asserts that he failed to obtain the 
crystals characteristic of zirconium, and that the chief and probably the only constituent 
of this substance is titanic acid, as the crystalline deposit in the bead exactly accords 
with the very peculiar forms assumed under the same conditions by that oxide. 
With so infinitesimal an amount of substance at one’s disposal it seems impossible to 
investigate further the nature of this element. Even the methods of the spectrum-ana- 
lysis are not yet reduced to a form available for determining the nature of an element 
of this group in so minute an amount. That it is not zirconium the evidence of so 
accurate an experimentalist as Mr. Sorby may be taken to prove ; that it is titanium seems 
scarcely compatible with the comparative experiments I made with it and with titanium 
chloride. It is certain, however, that Osbornite consists of calcium, and what may be 
provisionally termed a titanoid element, possibly titanium itself, with a trace of iron 
and combined with sulphur in some peculiarly stable form. This form can hardly be 
that of a combination of the sulphides of the metals merely ; one cannot well conceive 
such a compound resisting the action of acids. The sulphides of the metals of this 
class, however, are little known ; while those of calcium associated with oxygen in the 
form of what are termed oxysulphides need also further investigation. 
The fact of the Osbornite crystals being met with occasionally in the variety of augite, 
which will be presently described, as an ingredient of this meteorite, and which is for 
the most part confined to that nodule of the meteorite in which the Oldhamite occurs, 
suggested a search in that silicate for an oxide corresponding to what had been found in 
the Osbornite. The precipitates thrown down by ammonia from the acid solution of 
the bases in the different analyses of that augite were therefore brought together and 
examined. They contained some ferric oxide; but this was associated with a small 
amount of a colourless oxide entirely insoluble in potash, which, when tried by the tests 
that had been employed with the Osbornite precipitate, gave exactly the same results as 
these had given. The dichroism of this augite is very marked ; and on looking through 
one of its faces (the face 0 1 0) a tint (like that of the bluish anatase from Brazil) is seen 
