32 
SELECTED ARTICLES. 
ter is combined, and from which it may be withdrawn, slightly 
mixed with a free acid, by the use of sulphuretted hydrogen, 
and after the separation the acids act with it as I am about to 
describe. To obtain it pure, the acids must be completely 
separated; the best agent for this, is chalk in fine powder, 
which gives rise to a deposit of the malate and citrate of lime. 
Lime is then to be added in small quantities, to precipitate 
the neutral malate of lime contained in the liquid. The 
liquid is to be filtered, and mixed with a small quantity of 
acetate of lead; the bluish-green precipitate which is thereon 
formed, is to be separated, because it may contain some malate 
of lead, and the acetate of lead again added as long as any 
precipitate is produced. The green precipitate is to be 
collected on a filter and washed with water, after such a man- 
ner that it shall be always covered and protected against the 
least access of air. It is then to be decomposed by sul- 
phuretted hydrogen, and the filtered liquor evaporated to 
dryness in a vacuum, by the aid of sulphuric acid; the coloring 
matter which remains is to be dissolved in anhydrous alcohol, 
which leaves behind the coloring matter altered by the air, 
and the pectine or pectic acid. By distilling off the alcohol, and 
drying the residuum in a vacuum, the coloring matter is ob- 
tained as a beautiful red, transparent and brilliant mass. A 
great loss is sustained if we obtain in the beginning, by means 
of the acetate of lead, the blue precipitate of the malate or 
citrate of lead, then precipitate from the filtered liquor the 
coloring matter by subacetate of lead, and decompose the 
washed precipitate by sulphuretted hydrogen. In this state 
the coloring matter is soluble in every proportion in water 
and alcohol, but is insoluble in ether. It remains after the 
evaporation of the aqueous solution on a salt water bath; but 
it is under the form of a deposit less soluble in water, and but 
little so in alcohol; it is another coloring matter of a reddish- 
brown and less alterable; if we add to an aqueous solution of the 
coloring matter, a small quantity of lime water, it precipitates 
of a greenish-gray. The coloring matter not yet precipitated is 
red, but of another shade, for it contains a combination of lime 
