28 VETERINARY STATE BOARD 



LEAD 



Give (a) the symbol, (b) atomic weight, (c) valence, and (d) the physi- 

 cal properties of lead. 

 (a) Pb. (b) 205. (c) 2 and 4. (d) Lead is a soft, bluish- 

 white metal; specific gravity, 31.38. When freshly cut, it has a 

 bright metallic luster, but quickly tarnishes on the surface and 

 becomes dull. It is malleable and ductile. 



What is sugar of lead? Give its pharmaceutical name. 



Sugar of lead is a salt formed by the action of acetic acid on 

 lead oxide. It forms colorless, shining, transparent crystals, easily 

 soluble in water, and has a sweetish, astringent, afterwards metallic 

 taste. Formula, (C2H302)2Pb. 



Pharmaceutical name is plumbi acetate. 



MEECUET 



Describe mercury as to physical and chemical properties and occur- 

 rence in nature. 



Mercury is the only metal which is liquid at ordinary tempera- 

 ture ; it is almost silver-white and has a bright metallic lustre ; specific 

 gravity, 13.56. Pure mercury does not tarnish in the air until heated 

 above 300° C, when it unites with the oxygen to form the red oxide. 

 It combines directly with chlorine, bromine, iodine and sulphur and 

 dissolves in nitric acid and hot sulphuric acid. Its atomic weight 

 is 198.5. 



Mercury occurs in nature in a free state, but generally as mer- 

 curic sulphide {cinnabar), a dark-red mineral. 



Name the compounds of mercury used in medicine. 



Mercuric oxide, mercuric and mercurous chloride, mercuric 

 iodide, massa hydrargyri, unguentum hydrargyri, hydrargyri cum 

 creta. 



Write the formula of each of the following: (a) mercurous chloride, 

 (b) mercuric chloride. Mention the common name and im- 

 portant properties of each. 



(a) Hg^Cla, calomel, is a cholagogue cathartic, intestinal anti- 

 septic and diuretic. The formula is commonly written, EgCl. 



(b) HgCla, corrosive sublimate, is a violent poison, anSieptic, 

 and alterative. 



Write the chemical equation representing the preparation of calomel. 

 HgSO, + Hg + 2NaCl = Na^SO, + 2HgCl. 



