INORGANIC POISONS. 335 



tines and intestinal canal, where it causes a dilution 

 of the solid substance deposited there, and thus 

 acts as a purgative. 



Each of the salts just mentioned possess this 

 purgative action, which depends on a physical pro- 

 perty shared by all of them ; but besides this they 

 exercise a medicinal action, because every part of 

 the organism with which they come in contact 

 absorbs a certain quantity of them. 



The composition of the salts has nothing to do 

 with their purgative action ; it is quite a matter of 

 indifference as far as the mere production of this 

 action is concerned (not as to its intensity), whether 

 the base be potash or soda, or in many cases lime 

 and magnesia; and whether the acid be phos- 

 phoric, sulphuric, nitric, or hydrochloric. 



Besides these salts, the action of which does not 

 depend upon their power of entering into combi- 

 nation with the component parts of the organism ; 

 there is a large class of others which, when intro- 

 duced into the living body, effect changes of a very 

 different kind, and produce diseases or death, ac- 

 cording to the nature of these changes, without 

 effecting a visible lesion of any organs. 



These are the true inorganic poisons, the action 

 of which depends upon their power of forming 

 permanent compounds with the substance of the 

 membranes, and muscular fibre. 



Salts of lead, iron, bismuth, copper, and mer- 

 cury, belong to this class. 



