HYDRARGYR UM. 8 5 



Mercury, and Mercuric Pernitrate obtained by dissolving 

 Mercury inNitric Acid. (1) 3Hg + 8HN0 3 =3(Hg'2N< >,) 

 -f 2NO + 4H 2 0. (2) Hg2N0 3 -f Hg = 2HgO -f 2N0 2 . 



Characters. An orange-red powder, insoluble in 

 water. 



Impurities. Red lead and brick-dust ; detected by 

 being non- volatile. Nitrate of mercury; by yielding 

 nitrous vapours by heat. 



Dose. to 1 gr. 



Preparation. 



Unguentum Hydrargyri Qxidi Rubri. " Red 

 Precipitate Ointment." 1 in 8. 



g. Hydrargyri lodidum Viride. Green Iodide of 

 Mercury. Hgl. 



Source. Made by rubbing together Mercury and 

 Iodine in the presence of Rectified (Spirit. 



Characters. A dull green powder, insoluble in water. 



Impurity. Biniodide of mercury, found by long 

 keeping ; detected by being soluble in ether. 



Dose. 1 to 3 gr^ 



h. Hydrargyri Sulphas. Sulphate of Mercury. 

 HgS0 4 . 



Source. Made by dissolving Mercury in hot Sul- 

 phuric Acid, and drying. 



Characters. A white, heavy, crystalline powder. 

 Used only to prepare calomel and corrosive sublimate. 



From Hydrargyri Sulphas are made : 



a. Hvdrargyri Subchloridum. Subchloride of 

 Mercury. Calomel. HgCl. 



Source. Made by subliming a mixture of Sul- 

 phate of Mercury, Mercury, and Chloride of Sodium ; 

 and washing with boiling water. (1) HgSO 4 -+ 

 Hg - Hg 2 S0 4 . (2) Hg 2 S0 4 + 2Nad = 2HgCl + 



Characters. A dull white, heavy, nearly taste- 

 less powder, insoluble in water and spirit. 



Incompatible with iodide of potassium, nitro- 

 hydrochloric acid, hydrocyanic acid, solutions of 

 lime, potash, and soda. 



Impurities. Perchloride of mercury ; detected 

 by being soluble in warm ether. Other chlorides; 

 non-volatile. 



Dose. to 5 gr. 



