112 W. Gibbs—Analytical Notices. 
Precipitation of chromic acid by a baric salt was next exam- 
ined. Potassic dichromate was precipitated by baric acetate, 
with the following variations: 
I Salt precipitated by baric acetate at a boiling heat, and 
washed with water only; chromate weighed upon a porous earth- 
enware filter. 
1, 0°4617 gr. gave 0°7894 gr. BaCrO, = 51°41%, 
2. 0°4685 gr. “ 0°8022 : = 51°52%. 
II. Salt precipitated by baric acetate at a boiling heat, alcohol 
added, and the precipitate washed with a hot mixture of 3 parts 
water and 1 part alcohol of 90% and ignited. 
0°3802 gr. gave 0°6546 gr. BaCrO, = 51°78%. 
4, 0°5282 gr. “ 0°9069 gr. * = 51.66%. 
III. Salt precipitated by baric acetate without alcohol. Solu- 
tion after precipitation evaporated to dryness upon a water bath, 
then washed with hot water and ignite 
5. 0°5366 gr, gave 0°9229 gr, BaCrO, = 51°75%. 
6. 0°5355 gr. “ 0°9204 s = 51°714, 
small quantity of strong alcohol to the liquid, washing with 
water containing alcohol, and igniting. The wash-water need 
not contain more than ,;', of its volume of alcohol. The pre- 
salts are washed out. Finally, it is not necessary to welg 
the baric chromate upon a weighed filter. A very small quan- 
tity of the chromic acid is always reduced by the carbon of the 
filter in igniting, but the loss of weight is inappreciable. This 
method is much shorter than that which is usually employed, 
as the filtration and washing may be executed almost immedi- 
diately after precipitation. 
*,* 
were mixed with much larger but undetermined quantities of 
mercurous nitrate from the boiling solutions. In this manner 
the following results were obtained : 
1. 0°4120 gr. K,Cr, 0, gave 02130 gr. €r,0, = 51°74% Cr, 97. 
2, 0°3292 gr. * 091702. gr. 4. me BER... * 
%. 074548 ge S. Ooihi or 2 4 S118 45 
