INORGANIC POISONS. 383 



nated from the body in the ordinary way. Solubility 

 is necessary to give efficacy to any substance 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 retaining 

 it, without at the same time being rendered incapa- 

 ble of permitting liquids to penetrate through their 

 pores. A strong contraction and shrinking of the 

 surface is the general effect of contact with these 

 metallic bodies. But corrosive sublimate, and several 

 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 sugar 

 and honey, either into metallic copper, or into the 

 red suboxide, neither of which enters into combina- 

 tion with animal matter. It is well known that sugar 

 has been long employed as the most convenient 

 antidote for poisoning by copper. 



With respect to some other poisons, namely, hy- 

 drocyanic acid and the organic bases strychnia and 

 hrucia, we are acquainted with no facts calculated to 

 elucidate the nature of their action. It may, how- 

 ever, be presumed with much certainty, that experi- 

 ments upon their mode of action on different animal 



