PRESERVATION OF FRUITS BY DRTING. 183 



liave been successful, are those which have been formed 

 upon this principle. 



The chymical agents, which exert the most powerful in- 

 fluence over the products of the earth, are air, water, and 

 heat ; the action of these, however, is not equally powerful 

 •over all classes of plants; the soft and watery, and those 

 which approach the nearest to animal matter, decompose 

 most readily ; the principles of such are less coherent, less 

 strongly united than* of others; so that the action of disor- 

 ganizing agents upon them is prompt and effectual. 



All the methods now employed for the preservation of 

 ;bodies, consist in so far changing their nature, as to de- 

 prive them of the elements of destruction contained with- 

 in their own organs ; or in secluding the substances to be 

 preserved from contact with the destructive agents men- 

 tioned in the preceding paragraph ; or in causing them to 

 imbibe certain other substances, the anti-putrescenl quali- 

 ties of which counteract all action, whether of internal 

 or external agents. 



ARTICLE L 



On the Preservation of the Fruits of the Earth by 

 Drying. 



In all vegetable products, water exists in two different 

 states, one part of it being found free, and the other in a 

 state of true combination : the first portion, not being 

 confined except by the covering of fhe vegetable, evapor- 

 ates at the temperature of the atmosphere ; the second is 

 set free only at a temperature sufficiently high to decom- 

 pose the substances containing it : the first, though for- 

 eign to the composition of the vegetable, enters into every 

 part of it, dissolving some of its principles, serving as a 

 vehicle for air and heat, and being converted by cold into 

 ice ; by these several properties it greatly facilitates de- 

 composition : the second portion, from which no evil of 

 the kind arises, is found combined and solidified in the 

 plants, and its action is thus neutralized. Drying, then, 

 consists in depriving the product to be preserved of the 

 water contained in it in a free state, hy heat ; and Jfroin 



