254 Lopez. 
It scratches quartz, zircon, and emerald, slightly ; but is 
Seratehed by the oriental sapphire, corundum, and crysoberyl, 
easily, and by the spinelle ruby. 
ft possesses the property of double refraction in an equal 
degree with the topaz, as was indicated by several fragments, . 
the mineral being too opaque to exhibit it in the mass. 
8. Chemical Characters. 
Before Hare’s compound blowpipe, this mineral melts with 
ébullition into a white enamel. 
We put about 100 grains of it in powder, into a glass tumbler, 
and poured upon it a quantity of hot blue cabbage liquor. In 
four or five minutes, the liquor was changed to a lively green. 
On repeating the experiment with cold cabbage liquor, the 
change from blue to green was as decided ; though it required 
ene or two hours to effect it. 
We put a portion of this mineral, in powder, into a platina 
erucible, and poured upon it a quantity of distilled sulphuric 
acid. On applying heat, the glass plate that covered the 
crucible was in a short time acted upon over the whole sur- 
face exposed to the ascending gas, indicating in the most de- 
cided manner, the existence of fluoric acid in this mineral. 
This experiment was several times repeated with the same 
result, particular care being taken that the mineral was pure, 
and that no portion of fluor was mingled with it. 
To determine, with still greater certainty the nature of this . 
mineral, we were desirous of ascertaining the principal ele- 
ments that enter into its composition. To effect this object, 
we attempted the following analytical trials. We did not 
expect to obtain an accurate analysis; and therefore, did net 
pay that scrupulous attention to every part of the process 
which exact analysis requires. We are likewise aware, that 
some parts of the process are not so strictly scientific and 
direct as might have been pursued. 
Yet as it 1s not in our power at present to repeat the fol- 
lowing steps, we have put them down merely as a tentative 
process, in the belief that they may throw some light on the 
nature of thts mineral. 
A. Fifty grains of the mineral were reduced to an impal- 
pable powder in a porphyry mortar, and subjected to a full regl 
heat, in a covered platina grugible, for one hour. ‘The mass 
