52 CHYMISTRY APPLIED TO AGRICULTURE. 



In some countries, where good husbandry is much at- 

 tended to, the floors of the stables are paved and slightly 

 sloping, so that the urine flows off" into a reservoir, where 

 it is fermented with animal and vegetable substances, and 

 used to water the fields at the moment when vegetation 

 begins to be developed. 



The art of fermenting dungs with litter is still very in- 

 complete in some parts of France. In one place they let 

 it decay till the straw is completely decomposed ; in 

 another they carry it into the fields as soon as it is taken 

 from the stables. These two methods are equally faulty. 

 By the first, nearly all the gases and nutritive, juices are 

 dissipated and lost ; by the second, fermentation, which 

 can take place only in masses, will be but very imperfectly 

 carried on in the fields, and the rains can convey to the 

 plants only that portion of the nourishment afforded by 

 the manure, which they can obtain by a simple washing. 



The most useful art perhaps in agriculture, and that 

 whicli requires the most care, is the preparation of dung- 

 heaps. It requires the application of certain chymical 

 principles, which it is not necessary for me to explain, 

 since it is sufficient to point out to the agriculturist the 

 rules by which' he should be governed in his proceedings, 

 without requiring of him an extensive knowledge of the 

 theory upon which they are founded. 



Solid substances, whether animal, vegetable, or mineral, 

 do not enter into plants unless they are previously dis- 

 solved in water, or are drawn in with that fluid in a state 

 of extreme division. 



Animal and vegetable substances which are by their 

 nature insoluble in water, may, by being decomposed, form 

 new soluble compounds, capable of furnishing nourish- 

 ment for plants. 



Animal and vegetable substances deprived by the ac- 

 tion of water of their soluble particles, may, in the course 

 of their decomposition, form new compounds susceptible 

 of being dissolved. Of this I have given instances in 

 speaking of mould. 



That which renders the art of employing dung-heaps 

 difficult, in proportion as it is useful, is, that some meth- 

 ods which are adopted occasion the loss of a part of the 

 manure. In fact, when the clearings of the farm-yard are 

 carried fresh into the fields, and applied immediately to 

 the soil, vegetation is undoubtedly benefited by the salts 



