Insoluble Salts in Chemical Analysis. 
73 
ART. XXII— ON THE USE OF INSOLUBLE SALTS AS A MEANS 
OF SEPARATION IN CHEiWICAL ANALYSIS. 
By Horace Demarcay. 
[Extract.] 
A class of metallic oxides is characterized by its not fully 
saturating acids, and of only being soluble in an excess of 
these agents. To this class belong the oxides of iron, chrome, 
tin, bismuth, antimony, as well as the oxides of the electro- 
negative metals. Except when there is a powerful play of 
affinities, it is possible to precipitate these oxides. In fact, 
the carbonates of lime, barytes, strontian, or magnesia, mixed 
with a cold solution of oxide of iron, separate this metal so 
completely that the most sensible tests indicate no trace of it. 
Oxide of iron may thus be separated from the oxidule of the 
same metal, from the oxides of manganese, cobalt and nickel, 
with greater ease and certainty than by any other method. 
The carbonates of barytes and strontian should be preferred 
from the ease with which they can be separated from the 
fluid, in which they are partly dissolved, or from the oxide of 
iron precipitated with them. This plan is the best to obtain 
the oxide of cerium, entirely free from iron. 
The oxide of bismuth acts like the oxide of iron. Carbonate 
of barytes separates it from copper. In the same way it 
may be separated from lead, manganese and nickel. The 
carbonate of barytes likewise precipitates the oxides of anti- 
timony and tin from their solution in hydrochloric acid, and 
may serve to separate them from lead and copper, to which 
they are united in a variety of alloys. 
The oxidule of tin is not separated like the oxide from its 
solution by the carbonate of barytes. This may be taken 
advantage of to separate tin from antimony. The oxide of 
chrome acts like the oxide of iron with carbonate of barytes. 
Hence this metal may be separated from the oxides of nickel, 
of cobalt, of manganese and those spoken of when noticing 
the oxide of iron. If the solution contains iron, it will be 
Vol. L— No. 1. 10 
