182 CHYMISTRY APPLIED TO AGRTCULTURE^^ 



CHAPTER X. 



®N THE PRESERVATION OF ANIMAL AND VEGETABLE 

 SUBSTANCES. 



Each product of agriculture has its season ,- there are 

 few which the earth yields at all times. From this well- 

 known truth there result two incontestable facts ; the first 

 of these is, that in the years of abundance the production 

 is greater than the consumption, and consequently a part 

 is lost, and the remainder sold at a low price ; the second is, 

 that the consumption of the greater part of the articles of 

 agricultural produce takes place within one year, whilst, if 

 the agriculturist had sure means of preserving them, it 

 might be prolonged indefinitely, and thus the sale of them 

 rendered more profitable. The question of the best man- 

 ner in which the productions of the earth may be pre- 

 served^ is then one of the most important to be solved in 

 rural economy. 



Before making known the processes by which, as we 

 have learned from experience, agricultural products may be 

 preserved free from change, it is necessary to cast a glance 

 upon the causes by which that change is produced. 



The natures of all bodies which have ceased to live or 

 vegetate are changed, as soon as the physical or chymical 

 laws by which they were governed, cease to act ; the ele- 

 ments of which they were composed then form new com- 

 binations, and consequently new substances. 



Whilst an animal lives, or a plant vegetates, the laws of 

 chymical affinity are continually modified in its organs by 

 the laws of vitality ; but when the animal or plant ceases 

 to live, it becomes entirely subject to the laws of chymical 

 affinity, by which alone its decomposition is effected. 



The principles of the atmospheric air which is imbibed 

 by the organs of living bodies, whether animal or vegeta- 

 ble, are decomposed and assimilated by them, whilst dead 

 bodies are decomposed by its action. Heat is the most 

 powerful stimulant of the vital functions, yet it becomes 

 after death one of the most active agents in the work of 

 destru<;tion. Our efforts, then, for the preservation of 

 bodies ought to be directed to counteracting or governing 

 those chymical or physical agents, from the action of which 

 they suffer ; and we shall see that all the methods which 



