FERMENTATION OF PEAT AND TANNER's BARK. 437 



being carefully covered o^«r with a layer of peat to prevent the es- 

 cape of fertilizing vapors. By this method — first introduced to pub- 

 lic notice by the late Lord Meadowbank — the entire mixture is gra- 

 dually brought into an equable state of heat and fermentation, and 

 as a manure for the turnip crop, is said to be as efficacious as an 

 equal weight of unmixed farm-yard manure. 



5. Or the liquid manure of the farm-yard may be employed for the 

 same purpose, either in whole or in part. If the heap of mixed peat 

 and dung be watered occasionally with the liquid manure, the fer- 

 mentation will be more speedily effected, and at a less expense of 

 common farm-yard dung. Or the half-dried peat may be used un- 

 mixed, as an absorbent for the liquid of the farm-yard, by which, 

 without other aid, it wnll be brought into a state of fermentation with 

 comparative rapidity. 



c. Or instead of the liquid manure, the ammoniacal liquor of the 

 gas-Avorks may be employed, with less prominent benefit certainly, 

 but still with great advantage. 



d. Or the peat may be mixed with from one-sixth to one-fourth of its 

 bulk of fresh sea- weed, the rapid decay of which will gradually reduce 

 the entire heap into a fertilizing mass (British Husbandry, II., p. 417.) 



e. Or rape-dust in the proportion of 1 ton to 30 cubic yards may 

 be mixed with the half-dried peat from two to six weeks before the 

 time of sowing the turnip crop. The fermentation of the rape-dust 

 takes place so quickly, that this short time is usually sufficient to con- 

 vert the whole into a uniform and rapidly decaying mass. 



In short, it is only necessary to mix half-dried peat with any sub- 

 stance which undergoes rapid spontaneous decomposition — when it 

 will more or less speedily become infected with the sanie tendency to 

 decay, and will thus be rendered capable of ministering to the growth 

 of cultivated plants. 



2°. Tanner^s bark is still more difficult to reduce or to bring into a 

 rapid state of decomposition. Any of the methods above recommended 

 for peat, however, will to a certain extent succeed also with the spent 

 bark of the tan pits. But in the case of substancet so solid and refrac- 

 tory as the lumps of bark are, the admixture of a quantity of lime and 

 earth, so as to form a compost keap, is perhaps the most advisable 

 m.ode of procedure. The way in which lime promotes the decay of 

 woody fibre in such heaps has already been "explained (see p. 382.) 



§ 13. Use of charred vegetable matters as a manure. 



Soot and charcoal are the principal substances of this class which 

 have been more or less extensively eraployed for the purpose of in- 

 creasing the productiveness of the land. 



1°. Soot is a complicated and variable mixture of substances pro- 

 duced during the combustion of coal. Its composition, and consequent- 

 ly its effects as a manure, vary with the quality of the coal, with the 

 way in which the coal is burned, and with the height of the chimney 

 in which it is collected. 



Soot has. not been analyzes since the year 1826, when a variety ex 

 ammed by Braconnot was fou».i by him to consist in a thousand parts ol 



