LEAD. 285 



At a temperature of 60°, it dissolves in about 2-5 times its weight 

 of water, and in about an equal weight at 212°. It reddens the 

 vegetable blues, and has a slightly acidulous, styptic, metallic 

 taste. It is decomposed by the alkalies, earths, and hydro-sul- 

 phurets, and by astringent vegetable infusions. The sulphate of 

 zinc is used internally in medicine as an emetic, astringent, and 

 tonic. In a dose of from grs. x. to 5ss. it operates almost instan- 

 taneously as an emetic, and is frequently employed as such in cases 

 where the stomach has been rendered torpid by the action of 

 narcotic poisons. In a dose of one or two grains, given twice a- 

 day, it has been employed as a tonic in intermittent fevers, dyspnoea, 

 phthisis, fluor albus, and some convulsive affections, as pertussis, 

 chorea, and epilepsy ; also as an astringent in chronic dysentery. 

 As an external application, a solution of this salt in water, in the 

 proportion of grs. iss. to Si, of fluid, is the common astringent 

 injection in gonorrhoea, and a little diluted forms a useful collyrium 

 in the latter stages of ophthalmia. It is also used as a lotion in 

 excoriations, and some kinds of superficial inflammations. 



Acetate of Zinc. Acetitis Zi/ici. — This salt is formed by 

 adding acetate of lead to a solution of sulphate of zinc, when sul- 

 phate of lead is precipitated, and the acetate of zinc remains 

 dissolved. It is frequently used as an excellent collyrium in 

 ophthalmia, and an astringent injection in gonorrhoea, and is less 

 irritating than the solution of the sulphate. 



Genus VIII.— LEAD. 



Plomb, Fr. ; Piombo } It. ; Plomo, Sp.; Cfiu?nbo t Port. ; Bid, Ger ; Swinez, Iluss. 

 Soorb, Pers. ; Aniik, Arab. ; Sisa, Hind. ; Hih-yer,, Chin. 



Lead very rarely occurs in the native or pure state ; it is gene- 

 rally found mineralized with sulphur, with oxygen, and with 

 various acids, forming a great variety of ores. 



Sp. 1. SULPHURET OF LEAD, OR GALENA, Pl. XXXIX. fig. 



1,2. — Bleischweif, Werner; Plomb sulfure, Hatty* — The colour 



2b 



