{Red precipitate} (Old. Chem), mercuric oxide ({HgO}) a heavy
red crystalline powder obtained by heating mercuric
nitrate, or by heating mercury in the air. Prepared in the
latter manner, it was the {precipitate per se} of the
alchemists.
{White precipitate} (Old Chem.)
(a) A heavy white amorphous powder ({NH2.HgCl}) obtained
by adding ammonia to a solution of mercuric chloride
or corrosive sublimate; -- formerly called also
{infusible white precipitate}, and now {amido-mercuric
chloride}.
(b) A white crystalline substance obtained by adding a
solution of corrosive sublimate to a solution of sal
ammoniac (ammonium chloride); -- formerly called also
{fusible white precipitate}.