Hg2Cl 2 . A dull white, heavy, nearly tasteless powder. Insoluble in water, 

 alcohol or ether. 



2 Pilula Hydrargyri Subchloridi Composita. (Compound Cal- 

 omel Pill, Plummer's Pill.) Dose, 4-8 grs.; 2^-4 dgms. (In 1 or 2 pills). 

 22.5; Sulphurated Antimony, 22.5; Guaiacum Resin, 45. Castor Oil 

 (by weight), 9.27; Alcohol, q.s. Almost 1 gr. calomel in 4 grs. 



2 Unguentum Hydrargyri Subchloridi. 10; Benzoated 

 Lard, 90. 



2 Hydrargyrum Ammoniatum. Ammoniated Mercury. A white 

 powder, but little acted upon by water. 



2 Unguentum Hydrargyri Ammoniati. 10; White Paraffin Oint- 

 ment, 90 



3 Liquor Hydrargyri Nitratis Acidus. Mercuric nitrate in so- 

 lution in nitric acid. 



1 Unguentum Hydrargyri Nitratis. (Citrine Ointment.) Mer- 

 cury, 4; in Nitric Acid, 12. Cooled and added to a mixture of Lard, 16 

 in Olive Oil, 28. 



2 Unguentum Hydrargyri Nitratis Dilutum. 25; Soft Par- 

 affin, 75. 



Hydrargyri Nigra. Black Mercurial Solution. (Black 

 Wash.) Mercurous Chloride, 0.685 ; Glycerin, 5 ; Mucilage of Traga- 

 canth. 12.5; Solution of Lime, to 100. The Black oxide is formed Hg 2 Cl 2 + 

 Ca (OH) 2 = Hg.,O + CaCl 2 + H 2 O. 



x Lotio Hydrargyri Flava. Yellow Mercurial Lotion. (Yellow 

 Wash.) Mercuric Chloride, 0.46; Solution of Lime to 100. The yellow 

 oxide is formed. HgCl 2 + Ca (OH) 2 = HgO + CaCl 2 + H 2 O. 



x Liquor Arsenii et Hydrargyri lodidi. Dose, 5-20 min.; 0.3-1.2 

 c.c. 1 of Arsenious Iodide and 1 of Mercuric Iodide in 100 of Water. 



HYDRASTIS RHIZOMA. HYDRASTIS RHIZOME. (Golden Seal.) The 

 dried rhizome and roots of Hydrastis Canadensis. The rhizome is tor- 

 tuous, often branched, >^-l> inch long, 1/8-J^ inch thick; yellowish- 

 brown, on the upper surface ascending branches and on the lower num- 

 erous thin brittle roots : slight but characteristic odour ; taste bitter. Active 

 principles the alkaloids, hydrastine and berberine. 



1 Extractum Hydrastis Liquidum. Dose, 5-15 min.; 0.3-1 c.c. 

 An alcoholic extract. 



2 Tinctura Hydrastis. Dose, 30-60 min.; 2-4 c.c. 

 10; Alcohol 60%, 100: by percolation. 



Hydrogenii Peroxidi (See Liquor Hydrogenii Peroxidi, p. 71. ) 

 66 



