LEAD. 293 



vinegar : the vinegar acts chemically on the lead, a white 

 crust is formed on its surface, which, when it has accumulated 

 sufficiently, is scraped off, and reduced to a fine powder by leviga- 

 tion. According to Mr. Brande, it consists of one proportional of 

 oxide of lead=l 12, and one of carbonic acid=22, and is, there- 

 fore, a carbonate of lead. Tt is never given internally, but it forms 

 the basis of an ointment, (Ung. Cerussce, Ph. D.) which is princi- 

 pally used as an application to burns and superficial inflammation. 

 It is sometimes applied in fine powder to the excoriated cuticle of 

 infants, a practice, however, which appears not to be altogether 

 without danger, and is now very generally exploded. 



Salts of Lead. 



Acetate of Lead. Plumhi Acetas. — This salt is prepared by 

 boiling the carbonate of lead in distilled vinegar, until the acid 

 acquire a sweet taste, and evaporating the liquid, which, on cool- 

 ino, affords crystals. It is prepared on a large scale for the use of 

 the calico-printers, and is known in commerce under the name of 

 suvar of lead. When pure it is inodorous, and has a sweet astringent 

 taste : it crystalizes in flat, shining, acicular, four-sided prisms, with 

 dihedral summits, which are generally aggregated in irregular masses, 

 that have the appearance of lumps of sugar. Its specific gravity is 

 2-345. It is soluble in about three and a half times its weight of 

 distilled water ; and is also soluble in alcohol. It is decomposed 

 by hard water, by the alkalies, by most of the acids and neutral 

 salts, lime, magnesia, and all the sulphurets. According to Berze- 

 lius, the constituents of 100 parts arei 58*71 of oxide of zinc, 26-96 

 of acid, and 14-32 of water. 



From its astringent and sedative effects, acetate of lead has been 

 lon<* employed as an external application to inflamed and exco- 

 riated parts. " It has also acquired considerable celebrity as an 

 internal remedy, requiring, however, considerable caution in its 

 exhibition. Its principal use is in urgent cases of internal 

 haemorrhage, as of the lungs, stomach, or uterus ; and in conse- 

 quence of the violently spasmodic action of the bowels, which it is 

 apt to induce, it requires generally to be given with opium, and 



