_Grey Oxyd of Mercury._
QUALITIES. _Form_, an impalpable grey coloured powder, which becomes
paler on exposure to air and light. _Odour_ and _taste_, none. CHEM.
COMPOSITION. When properly prepared it is protoxide of mercury; but, as
frequently found in the shops, it contains a mixture of the triple salt
consisting of oxide of mercury, ammonia, and nitric acid. It is rarely
used; although Dr. Saunders suggested it as a succedaneum for Plenck’s
remedy, and Mr. Abernethy considers it preferable to the red Sulphuret
for mercurial fumigation, on account of its not yielding any suffocating
vapour. OFFICINAL PREP. _Unguent._ _Oxyd. Hydrarg. ciner._ E.