a mineral Substance from North America. 63 
acidifiable metals, viz. arsenic, tungsten, molybdena, and chro- 
mium; as to the other metals lately discovered, such as ura- 
nium, titanium, and tellurium, they are still farther removed 
from it. 
The colours of the precipitates produced by prussiate of pot- 
ash and tincture of galls, approach the nearest to those afforded 
by titanium. But the prussiate of the latter is much browner; 
and the gallate is not of an orange colour, but of a brownish 
red, inclining to the colour of blood. Besides, even if these pre- 
cipitates were more like each other, still the obstinacy with 
which titanium refuses to unite with the fixed alkalis, and the 
insolubility of it in acids when heated, sufficiently denote the 
different nature of these two substances. 
The iron in the ore which has been examined, is apparently 
in the same state as it is in wolfram, viz. brown oxide; and 
this oxide is mineralised by the metallic acid which has been 
described, in the same manner as the oxides of iron and man- 
ganese are mineralised by the tungstic acid or rather oxide. 
For, from several experiments made upon a large scale, I have 
reason to believe that in wolfram, the tungsten has not attained 
the maximum of oxidation. Several facts in the course of the 
experiments lately described, seem to prove, that this new metal 
differs from tungsten and the other acidifiable metals, by a more 
limited extent of oxidation ; for, unlike these, it seems to be 
incapable of retaining oxygen sufficient to enable the total 
quantity to combine with the fixed alkalis. In § II. G. 2, this 
is very evident; for, from the experiment there described it 
appears, that when the metallic acid or oxide was digested with 
lixivium of potash, only a part was dissolved ; and that the re- 
mainder was insoluble in the same lixivium, till it had received 
