hillebkand.] CALCIUM AND BTBONTIUM (BARIUM). 63 
SEPARATION OF STRONTIUM (BARIUM) FROM CALCIUM BY ETHER-ALCOHOL. 
The thoroughly dried nitrates are treated with as little (rarely over 
2 cm. 3 ) of a mixture in equal parts of absolute alcohol and ether as 
may be needed to dissolve the calcium salt, solution being hastened by 
occasional gentle agitation. After standing over night in a corked flask 
the insoluble matter is collected on the smallest possible filter and 
washed with more of the above mixture of alcohol and ether. After 
drying, a few cubic centimeters of hot water are passed through the 
filter, on which may remain a few tenths of a milligram of residue 
which does not usually contain any lime or other alkaline earth and 
whose weight is therefore to be deducted from that of the lime, unless 
it can be shown that it is derived from the glass of the little flask in 
which the nitrates of calcium and strontium were evaporated. To the 
solution of strontium nitrate in a small beaker sulphuric acid and then 
alcohol is added, whereb}^ the strontium is precipitated as sulphate, in 
which form it is weighed and then tested spectroscopically as to free- 
dom from calcium and barium. 
Because of the slight solubility of strontium nitrate in amyl alcohol 
the method of Browning 1 does not appear to be adapted to the sepa- 
ration from calcium of the small amounts of strontium met with in 
rocks, though with barium the case is different, since its nitrate accord- 
ing to Browning is insoluble in absolute amyl alcohol. 
BEHAVIOR OF BARIUM. 
Barium will, after two ammonium oxalate precipitations, never be 
found with the ignited calcium and strontium in more than spectro- 
scopic traces, unless originally present in excess of 3 or 4 milligrams, 
and very often only when in considerable excess. 2 If present with 
them, however, it will be separated with the strontium by ether-alcohol 
or amyl alcohol, and these two must then be treated by the ammonium- 
chromate method, given below, in order to arrive at the strontium. 
The barium is best estimated in a separate portion. (See Barium, p. 73.) 
SEPARATION OF BAKIUM FROM STRONTIUM. 
Fresenius has shown 3 in what manner only a correct separation of 
barium and strontium can be made by the ammonium-chromate method, 
involving double precipitation when the amounts are at all large. This 
procedure is here given for theamounts used by him, but a single pre- 
cipitation will suffice for the small amounts met with in rock analysis. 
i Am. Jour. Sci., 3d series, Vol. XLIII, pp. 50, 314, 1892. 
2W. F. Hillebrand: Jour. Am. Cheru. Soc., Vol. XVI, p. 83, L894; Chemical News, Vol. LXIX.p. 147, 
1894. 
aZeitschr. fur anal. Chemie, Vol. XXIX, p. 428, 1890. 
