RED MERCURIC OXIDE 193 



Hydrargyri Oxidum Rdbrum. Eed Mercuric Oxide. HgO. 

 (U. S. & B. P.) 



Synonym. — Hydrargyrum oxydatum rubrum, P. G.; 

 hydrargyri-nitrico-oxydum, mercurius corrosivus (praecipi- 

 tatus) ruber, oxydum hydrargyri cum, peroxide of mercury, 

 red precipitate, mercuric oxide, E.; deuto-oxyde (peroxyde) 

 de mercure, oxyde mercurique, precipite rouge, poudre de 

 Jean de Vigo, Fr.; rotbes quecksilberoxyde, rother pracipi- 

 tat (quecksilber-pracipitat), G. 



Derivation. — Dissolve mercury in diluted nitric acid. 



3 Hg, H- 16 HNO3 = 6 Hg (N0,\. (Mercuric nitrate) 

 + 4 NO + 8 H,0. 



Rub mercuric nitrate with metallic mercury and heat. 



2 Hg (NOJ, + Hg, = 4 HgO + 2 N,0, ■ 



Properties. — Heavy, orange-red, crystalline scales, or a. 

 crystalline powder ; odorless, and having a somewhat 

 metallic taste ; permanent in the air ; almost insoluble in 

 water ; insoluble in alcohol. 



PREPARATION. 



Unguentum Hydrargyri Oxidi Rubri. Ointment of Red Mercuric Oxide. 



(U. S. & B. P.) 



Synonym. — Red precipitate ointment, red mercuric oxide, 10; cas- 

 tor oil, 5; ointment, 85. (U. S. P.) 



Hydrargyri Oxidum Flavum. Yellow Mercuric Oxide. HgO. 

 (U. S. & B. P.) 



Synonym. — ^Hydrargyrum oxydatum via humida para- 

 tum, P. G.; hj^drargyrum oxydatum prsecipitatum (vel 

 flavum), precipitated oxide of mercury, E.; oxyde de mercure 

 jaune (precipite), Fr.; pracipitirtes (Gelbes) quecksilber- 

 oxyde, G. 



Derivation. — Precipitate an aqueous solution of mercuric 

 chloride, 100, with caustic soda, 40 : HgCl, + 2 NaOH = 

 HgO + 2 NaCl -f H,0. 



