ZINC OXIDE 237 



high temperatures, but between 212 and 300 Fahr. it is 

 ductile and malleable. Its salts are colourless. 



ACTIONS AND USES. Zinc salts unite with albumin to 

 form an insoluble precipitate, and hence are astringent. As 

 solids and concentrated solutions, several are irritant and 

 caustic, and being deliquescent they tend to spread. Al- 

 though not affecting the unbroken skin, when applied to 

 mucous membranes small doses are astringent, large doses 

 are irritant. The chloride, nitrate, and iodide are readily 

 soluble and diffusible, and hence are active and corrosive. 

 The sulphate and acetate, although less energetic, have more 

 activity than the less soluble oxide or carbonate. The 

 sulphate and acetate are prompt emetics for dogs and other 

 animals that vomit, and unlike tartarised antimony, they 

 cause little depression of the circulation. They produce 

 emesis chiefly by local action on the stomach. Continued 

 full doses produce symptoms allied to those of acute poison- 

 ing by copper or lead, due to the local irritant effect in the 

 stomach and intestine. They are absorbed very slowly as 

 albuminates, and produce no characteristic effects, but 

 injected intravenously, depression of the central nervous 

 system and of muscle tissue is produced as with copper. 

 They are eliminated more rapidly than mercury, lead, or 

 copper, in small quantity by the kidneys, but chiefly by the 

 liver and intestinal glands (Bartholow). 



ZINC OXIDE. Zinci Oxidum. Oxide of Zinc. ZnO. 



Oxide of zinc may be prepared by exposing zinc carbonate 

 to a dull red heat, or from metallic zinc by combustion. It 

 is a soft, nearly colourless, tasteless, inodorous powder, in- 

 soluble in water, but soluble without effervescence in acids 

 and in alkalies. When heated it becomes yellow, but if free 

 from iron nearly loses its colour on cooling. 



ACTIONS AND USES. It is a desiccant, protective, and haemo- 

 static, but, being insoluble in water, it acts mechanically un- 

 less dissolved by an acid, when it is mildly astringent. It is 

 occasionally prescribed in catarrh and bronchitis for the 

 arrest of profuse secretion, is said to be a nerve sedative, and 

 is given to dogs in epilepsy and chorea. 



