388 POISONS, CONTAGIONS, MIASMS. 



remedies and strong nourishment, the chemical action may finally 

 be subdued, or, in other words, the disease cured. 



The conversion of starch into sugar may also be effected by 

 pure gluten, and by dilute mineral acids. 



From all the preceding facts, we see that very various trans- 

 positions, and changes of composition and properties, may be 

 produced in complex organic molecules, by every cause which 

 occasions a disturbance in the attraction of their elements. 



When moist copper is exposed to air containing carbonic acid, 

 the contact of this acid increases the affinity of the metal for the 

 oxygen of the air in so great a degree that they combine, and 

 the surface of the copper becomes covered with green carbonate 

 of copper. Two bodies which possess the power of combining 

 together, assume, however, opposite electric conditions at the 

 moment in which they come in contact. 



When copper is placed in contact with iron, a peculiar electric 

 condition is excited, in consequence of which the property of the 

 copper to unite with oxygen is destroyed, and the metal remains 

 quite bright. 



When formate of ammonia is exposed to a temperature of 

 388° F. (180° C), the intensity and direction of the chemical 

 force undergo a change, and the conditions under which the ele- 

 ments of this compound are enabled to remain in the same form 

 cease to be present. The elements, therefore, arrange them- 

 selves in a new form ; hydrocyanic acid and water being the 

 results of the change. 



Mechanical motion, friction, or agitation, is sufficient to cause 

 a new disposition of the constituents of fulminating silver and 

 mercury, that is, to effect another arrangement of their element?, 

 or to cause the production of new compounds in a liquid. 



We know that electricity and heat possess a decided influence 

 upon the exercise of chemical affinity ; and that the attractions 

 of substances for one another are subordinate to numerous causes 

 which change the condition of these substances by altering the 

 direction of their attractions. In the same manner, therefore, the 

 exercise of chemical powers in the living organism is depondent 

 upon the vital principle. 



The power of elements to unite together, and to form the 



