hillebrand.] BARIUM (ZIRCONIUM, TOTAL SULPHUB). 73 
Ti0 2 . The titanium which came down in excess of this amount did 
not settle out in flocculent condition, as happens when zirconium is not 
present, and it was difficult to filter. After the removal of the 
zirconium in the manner to be hereafter described (p. 75), however, 
no difficulty was experienced in precipitating all the titanium with the 
usual ease. 
SUPERIORITY OF THE COLORIMETRIC AND GOOCH METHODS OVER THE OLDER ONES. 
In view of the good results obtainable by the colorimeter method in 
all eases and by the Gooch method in the absence of zirconium, it is 
incomprehensible that the old method of precipitation by many hours' 
boiling in a nearly neutral sulphate solution in presence of sulphurous 
acid should still find adherents in any part of the world. 
Attention has been directed (p. 60) to the error resulting from 
attempting to separate aluminum from titanium by either fused or 
dissolved sodium hydroxide. 
baskerville's method. 
Baskerville 1 has proposed the separation of titanium from iron and 
aluminum by boiling the neutralized solution of the chlorides for a 
few minutes in presence of sulphurous acid. The test separations as 
given by him are sharp, and a single precipitation is said to suffice, the 
titanium being free from iron and easily filterable. This last statement 
and the ready precipitability are fulty confirmed by the experiments 
of the writer on titaniferous iron ores, but, although the titanium is 
completely thrown out, it carries with it a little iron, for instance, 
about 0. 25 per cent Fe 2 3 with 8 to 10 per cent Ti0 2 . Zirconium would 
probably be likewise precipitated (see p. 77) and phosphorus per- 
haps also, but this last point has not been investigated, neither has the 
applicability of the method to aluminous rocks been tested. 
XIII. BARIUM (ZIRCONIUM, TOTAL SULPHUR). 
Reasons for estimating barvu/m in <i separate portion of rock jxnoder. — 
It has been said above (p. 03) that only in very exceptional cases will 
barium he found with the calcium and strontium after two, or possibly 
three, precipitations of the latter as oxalate, since it passes into the 
filtrates with the magnesium, whence it may he obtained as sulphate 
after removal of ammoniacal salts. Addition of some alcohol insures 
also the recovery of traces of strontium if the rocks are \rvy rich in 
it. But it is unsafe to regard the amount thus separated from the 
magnesium as represent inn - the total amount of barium in the rock. It 
ijour. Am. Chem. Soc, Vol. XVI, p. 127, L894. 
