342 POISONS, CONTAGIONS, MIASMS. 



is eliminated from the body in the ordinary way. 

 Solubility is necessary to give efficacy to any sub- 

 stance in the human body. 



The soluble salts of lead possess many properties 

 in common with the salts of silver and mercury ; but 

 all compounds of lead with organic matters are 

 capable of decomposition by dilute sulphuric acid. 

 The disease called painter's colic is unknown in all 

 manufactories of white lead in which the workmen 

 are accustomed to take as a preservative sulphuric 

 acid-lemonade (a solution of sugar rendered acid 

 by sulphuric acid). 



The organic substances which have combined 

 in the living body with metallic oxides or metallic 

 salts, lose their property of imbibing water and re- 

 taining it, without at the same time being rendered 

 incapable of permitting liquids to penetrate through 

 their pores. A strong contraction and shrinking of 

 a surface is the general effect of contact with these 

 metallic bodies. But corrosive sublimate, and seve- 

 ral of the salts of lead, possess a peculiar property, 

 in addition to those already mentioned. When 

 they are present in excess, they dissolve the first 

 formed insoluble compounds, and thus produce an 

 effect quite the reverse of contraction, namely, a 

 softening of the part of the body on which they 

 have acted. 



Salts of oxide of copper, even when in combina- 

 tion with the most powerful acids, are reduced by 

 many vegetable substances, particularly such as 



