378. POISONS, CONTAGIONS, MIASMS. 



the organism with which they come in contact ab- 

 sorbs 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 phosphoric, 

 sulphuric, nitric, or hydrochloric. 



Besides, these salts, the action of which does not 

 depend upon their power of entering into combina- 

 tion with the component parts of the organism, there 

 is a large class of others which, when introduced 

 into the living body effect changes of a very different 

 kind, and produce diseases or death, according 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 per- 

 manent compounds with the substance of the mem- 

 branes, and muscular fibre. 



Salts of lead, iron, bismuth, copper, and mercury, 

 belong to this class. 



When solutions of these salts are treated with a 

 sufficient quantity of albumen, milk, muscular fibre, 

 and animal membranes, they enter into combination 

 with those substances, and lose their own solubility ; 

 while the water in which they were dissolved loses 

 all the salt which it contained. 



The salts of alkaline bases extract water from 

 animal substances; whilst the salts of the heavy 

 metallic oxides are, on the contrary, extracted from 

 the water, for they enter into combination with the 

 animal matters. 



Now, when these substances are administered to 

 an animal, they lose their solubility by entering into 

 combination with the membranes, cellular tissue, and 

 muscular fibre ; but in very few cases can they reach 

 the blood. All experiments instituted for the pur- 

 pose of determining whether they pass into the urine 



