426 SALTS OF THE HEAVY METALS 



Earely used except in preparation of Goulard's Extract and lead 

 plaster. 



Preparation. 



Emplastrum Plumbi. Lead Plaster. Diachylon Plaster. 



Lead plaster is prepared by adding lead oxide to a hot solution 

 of equal weights of lard and olive oil. It makes a useful protec- 

 tive dressing for superficial ulcers and bed sores. Equal parts of 

 lead plaster and petrolatum make an efficacious application in sub- 

 acute eczema. Lead Plaster also enters into all the official plasters 

 and Diachylon Ointment. 



Unguentum Diachylon. 



B Lead plaster 50 gm. 



Oil of lavender 1 gm. 



White Petrolatum 49 gm. 



Melt the lead plaster and white petrolatum, strain, cool, and add the 

 oil of lavender. 



HYDRARGYRUM — MERCURY 



Mercury differs from the other metals in having a marked spe- 

 cific toxic action upon protoplasm. It is toxic to both higher and 

 lower forms of life and has very strong antiseptic properties. Its 

 action is due to its affinity for proteid molecules. Mercury forms 

 albuminoids with the proteids of the tissues which are soluble in an 

 excess of the albumen, alkali or sodium chloride solution, so that it 

 is quite readily absorbed. It differs also from the other metals 

 in exerting a definite constitutional action which lasts for some 

 time after its administration, ' due to the slowness of elimination. 

 Furthermore, while most metals are harmless in their free or metal- 

 lic state, mercury is very toxic. It is absorbed and distributed 

 throughout the body rapidly on account of its being volatile, liquid 

 and easily oxidized. Mercury compounds are absorbed from all 

 surfaces of the body and consequently may be administered per os, 

 inunction, inhalation and fumigation. 



Elimination. Mercury is eliminated slowly, chiefly by the in- 

 testinal canal but also to some extent by the urine, saliva, sweat and 

 milk. The elimination by the kidneys starts promptly but is \ery 

 slow and has been known to persist for 8 days after a single dose. 

 It is largely retained in the body in the internal organs as in the case 

 of lead, and soon disappears from the blood. 



If small amounts are administered over a long period of time, 

 the first symptoms will be noticed in the mouth, as shovTu by saliva- 

 tion, soreness of the gums and teeth, and fetor of the breath. 

 Later, if the administration is kept up, the gums will become swollen, 

 the teeth, loosened and fall oiit, salivation will be profuse, tongue 

 and glands, enlarged and the bones, necrotic. These symptoms con- 



