On Paring and Burning. 7 



It is evident at the same time that it is impossible for prac- 

 tical men thoroughly to comprehend how far certain scientific 

 principles are applicable in a particular case if these principles 

 themselves are misunderstood ; nor can it be expected that a 

 place will be secured for science in the affections of the prac- 

 tical man if the teachers of science be unacquainted, or but very 

 imperfectly informed, on practical matters. Scientific men too 

 often fall into the grievous error of insisting upon the applica- 

 tion of abstract principles under all circumstances. 



Chemical principles, though they may not always find a direct 

 application in agriculture, or though, when stated in the abstract, 

 they may require to be greatly modified in practice, are, how- 

 ever, of primary utility to the occupier of land. The want of 

 a clear perception of a scientific truth, and its bearing upon the 

 farm routine, as followed in this or that locality, is a fertile 

 source of endless disputes. In order fully to appreciate the 

 objections of those who, I think, attach, generally speaking, too 

 great an importance to the organic matters in the soil, it appears 

 to me desirable to allude briefly to the functions of humus, i. e. 

 organic matters in a state of progressing decomposition. I 

 would, therefore, observe : 



1. Humus is an excellent absorber of moisture, and for this 

 reason of special use in sandy and other naturally dry soils. In 

 illustration of this property, the following partial analyses of two 

 soils may find here an appropriate place. Both soils are from 

 Buckinghamshire. Before proceeding with their analysis, I 

 kept them in a heated room, in a powdered state, until they 

 were perfectly airdry, neither gaining nor losing water when 

 weighed from day to day. In this state they were analysed, and 

 the following results obtained : 



No. I. No. IL 



Moisture 4*70 22*35 



Organic matter and water of combination .. 5*98 22*01 



Oxides of iron and alumina 10*51 16*02 



Carbonate of lime .. 1*32 '95 



magnesia *85 *43 



Phosphoric and sulphuric acid trace trace 



Alkalies, chlorine, and loss *47 '56 



Insoluble silicious matter (chiefly sand) .. 76*17 37*68 



100*00 100*00 



No. I. was a soil in wheat, No. II. soil in permanent pasture. 



The wheat soil, it will be seen, contained nearly 6 per cent, 

 of organic matter, and retained, in a moderately-dry atmosphere, 

 about 5 per cent, of moisture, which was only driven off at the tem- 

 perature of boiling water. The pasture-land contained 22 per 

 cent, of organic matter, and, under the same circumstances in 

 which No. I. retained only 5 per cent, of moisture, was capable 

 of retaining no less than 22 per cent. 



