Ctt MANURES, 189 



It is however a question demanding the combined efforts 

 of the chemist and the farmer, not reafoning but experi- 

 menting. TTff fl^, 



The effect of heat in this operation is remarkable. Where- £»<**©* «***- 

 everburning has been much practised, experience has de- 

 monstrated the necessity of removing ail the ashes where 

 the fires were made ; and though careful farmers remove 

 some of the uncalcined earth, still these spots manifest a 

 deeper green in the crop, than is observable in any other 

 part of the field. The general warmth diffused may proba- 

 bly have a greater effect than is suspected. 



-2. The Properties of the Ashes resulting from Paring and 

 Burning. 



Vegetable ashes imbibe carbonic acid from the at raos- Properties of 

 phere*. They act in decomposition, and yield three tbe * siias - 

 fourths in carbonic acid, and one fourth a little inflamma- 

 ble ; and last many years, by reabsorbing in winter the 

 principles they had lost in summer f. 



I imagine that the advantage of paring and burning 

 some soils depends on the heat emitted from the burning 

 vegetable fibres uniting oxygen with the clay, which forms 

 more than the half of the slices of turf as they are dug 

 from the ground £. 



That the ashes produced by paring and burning operate 

 as a very powerful manure, cannot be doubted ; since in 

 nine tenths of the trials that have been made through the 

 wide range of so many counties, the crops which followed 

 have been found to be very great indeed, and generally su- 

 perior to those procured by means of any other manure. 

 It is not the want of this success that has mado so many Caution, 

 enemies to the practice, but rather the contrary ; the crops 

 have been so large, and so often repeated, because great, 

 that the soil has been Left in a state of exhaustion. 



This is a subject that demands the attention of the expe- 

 rimental chemist more than most others in the theory of 

 agriculture. The examinations which have been made on 



• Priestley. f Fabbroni. J Darwio. 



the ' 



