On Paring and Burning. 243 



for wheat. Thus the improvement would never stop, while 

 the weather permitted the processes to be continued ( 3 9 ). 



7. Nature of the Ashes> and the Substances mixed with them. 

 It is proved by innumerable trials, that the substances pro- 

 duced by paring and -burning, constitute a most powerful 

 manure, and that greater crops may be thus procured, than 

 by any other means. That much benefit results from these 

 substances, is put beyond doubt by the circumstance, that 

 if they are removed, the succeeding crop suffers greatly ( 3l ). 

 The nature of these substances may be thus explained : 

 1. When the earth has been thoroughly heated by fire, its 

 particles, if separated, lose the quality of coalescing; it free- 

 ly admits, therefore, the delicate fibrous roots of young 

 plants, and thus promotes their vegetation. 2. Another 

 property which these substances possess, is, the power of im- 

 bibing water, and retaining it in the earth, for the purposes 

 of vegetation ; and hence their utility, in all those thin and 

 chalky soils, where moisture is desirable ( 3M ). 3. Soils sus- 

 ceptible of the greatest improvement from burning, contain 

 a considerable portion of oxide of iron, which the process 

 tends to decompose, and the oxygen thus obtained, may 

 unite with the carbon of the ashes, and produce great ferti- 

 lity. 4. After it cools, the earth probably retains latent 

 heat, which it may communicate to growing plants ( 3ia ). 

 The carbonaceous matter produced by burning is, however, 

 the substance of the greatest importance. Though the char- 

 coal of perfect wood, or of pit-coal, has hitherto been found 

 insoluble, that of the smaller sorts of vegetables readily dis- 

 solves in water, and administers food to plants. Great care 

 should therefore be taken, to conduct the process of burn- 

 ing in such a manner, as to preserve this useful article. This 

 may be done effectually, by burning the turf in large heaps, 

 covered with fine mould, so as to keep up a slow smother- 

 ing fire ; and in this way, the whole vegetable matter contain- 

 ed in the turf, may be converted into a carbonaceous sub- 

 stance ( 3I3 ). Burning should never be carried so far, as 

 some writers have recommended. It is sufficient, if the liv- 

 ing vegetable principle in the plants, and in their roots, is 

 destroyed, and the texture of the mass so completely re- 

 duced, that it may become a productive soil. Hence, all 

 violence of heat is to be avoided, and a slow smothering fire, 

 is the object to be kept in view ( 3l4 ). 



8. Mode of managing the Ashes. There are four modes. 

 1. To spread and plough immediately after they are burnt. 

 This is the common method, and probably the best ( 3l5 X 



