CHAPTER IX. 



MISCELLANEOUS EXAMPLES OF THE FOUR METHODS. 



1. I SHALL select, as a first example, an interesting 

 speculation of one of the most eminent of theoretical chemists, 

 Baron Liebig. The object in view, is to ascertain the imme- 

 diate cause of the death produced by metallic poisons. 



Arsenious acid, and the salts of lead, bismuth, copper, 

 and mercury, if introduced into the animal organism, except 

 in the smallest doses, destroy life. These facts have long 

 been known, as insulated truths of the lowest order of 

 generalization ; but it was reserved for Liebig, by an apt em- 

 ployment of the first two of our methods of experimental 

 inquiry, to connect these truths together by a higher induc- 

 tion, pointing out what property, common to all these dele- 

 terious substances, is the really operating cause of their fatal 

 effect. 



When solutions of these substances are placed in suffi- 

 ciently close contact with many animal products, albumen, 

 milk, muscular fibre, and animal membranes, the acid or salt 

 leaves the water in which it was dissolved, and enters into com- 

 bination with the animal substance : which substance, after 

 being thus acted upon, is found to have lost its tendency to 

 spontaneous decomposition, or putrefaction. 



Observation also shows, in cases where death has been 

 produced by these poisons, that the parts of the body with 

 which the poisonous substances have been brought into con- 

 tact, do not afterwards putrefy. 



And, finally, when the poison has been supplied in too 

 small a quantity to destroy life, eschars are produced, that is, 

 certain superficial portions of the tissues are destroyed, which 

 are afterwards thrown off by the reparative process taking 

 place in the healthy parts. 

 VOL. i. 29 



