60 Contributions to Chemistry from the 
stand some hours before filtering. In general, the precipitation 
by acetate of lead or acetate of barium is to be preferred even 
when the resulting chromate is to be weighed as such. eg 
2. 
i 
by boiling the neutral or nearly neutral solutions with acetate of 
sodium, provided that the following precautions are obse 
The solutions from which the sesquioxyds are to be precipi 
must be dilute: half a liter of the solution should not conta 
more than one gram of either sesquioxyd or of the two whet 
both are present. The quantity of acetate of sodium should be 
sufficient to convert by double decomposition all the bases preset 
into neutral acetates. The acetate should be added to the me 
lic solution when cold and the whole should then be heated 
gether and boiled for ashort time. It is not necessary to filtet 
the last traces of the stronger bases. Finally, the basic salts 
the iron and aluminum, after washing,.must be redissolved 
i manner, to free them completely from alkali. ve 
caution of a second treatment with acetate of sodium is mo® 
necessary with alumina than, with sesquioxyd of iron aloné 
It is — worth the trouble in the separation of iron 
