130 Scientific Intelligence. 
titanic acid, oxyd of iron ought to be entirely absent, as it either p 
vents its precipitation altogether, or materially retards it. This is, 
fact, the great reason why titanic acid has been so frequently overlooke 
and so many errors made. Some special experiments on this point wil 
be found in my paper previously alluded to. be 
Titanium may, however, be found more satisfactorily and more re 
during the process usually adopted to determine the amount of grapht 
t 
each other, and the filter well washed to remove all the iron. Iti : 
then treated with dilute potash, and washed once; then re- biog 
i as to remove entirely the silica. The potash was thoroug 
washed out, and the filter treated with chlorhydric acid, thoro 
washed and dried at 250° F., until the weight was constant. This garé 
the graphite, on burning which a residue of a dirty light brown color 
was left, which, on being fused with bisulphate of potash and treated 
ie acid, as will, 
before, proved that the residue was nearly pure titani 
seen from the results below :— 
Graphite and _ Residue Titanic acid 
of pigtaken. Titanic acid. after burning. obtained. — 
No.1 Pig 205°68 7°82 1-28 1-085 
“9% 05 185 "835 “145 
«3 21686 7-04 83 28 
and redissolved in chlorhydric acid—is given below :— 
rains bee : 
of pig taken. Silica obtained. 
No.1 120°845 4:29 
“ 9 127-93 8°659 “20 
“ 3 122°55 9-22 265 
taric acid is destroyed; in either case the residue is fused with of 
or where nitric acid is used, this is driven off with sulphuric aci : 
bisu tash is dissolved in cold water, boiled for some hours, @ 4 
to a ni arm place, when the titanic acid is filtered off an 
t in a wi 
with dilute sulphuric acid—dried, ignited, and weighed. If the 
bi id is not required, then the precipitate produced ( 
“ dri ; 
* 
8s even in sn has a very ect i , 
tion of titanic acid, so that it is always advisable to add a littl 
which reduces the oxyd of iron and facilitates the precipitation of 
