261 
crops do not abstract a particle of silica, and therefore leave the 
field equally fertile for the following crop of wheat.” 
“The preceding remarks will render it obvious to you, that 
the mechanical working of the soil is the simplest and cheapest 
method of rendering the elements of nutrition contained in it 
accessible to plants.” 
“ But, it may be asked. Are there not other means of decom- 
posing the soil besides its mechanical subdivision — are there 
not substances, which by their chemical operation shall equally 
well or better render its constituents suitable for entering into 
vegetable organisms? Yes: we certainly possess such sub- 
stances, and one of them, namely, quick-lime, has been em- 
ployed for the last century past in England for this purpose : 
and it would be difficult to find a substance better adapted to 
this service, as it is simple, and, in almost all localities, cheap 
and easily accessible. ’ 
“In the month of October the fields of Yorkshire and Oxford- 
shire look as if they were covered with snow. Whole square 
miles are seen whitened over with quick-lime, which, during 
the moist winter months, exercises its beneficial influence upon 
the stiff clayey soil of those counties. The fertility of the soil 
is increased by the lime. The ceralia require the alkalies and 
alkaline silicates, which the action of the lime renders fit for 
assimilation by the plants. If, in addition to these, there is any 
decaying organic matter present in the soil supplying carbonic 
acid, it may facilitate their development ; but it is not essential 
to their growth. If we furnish the soil with ammonia, and the 
phosphates, which are indispensable to the ceralia, with the 
alkaline silicates, we have all the conditions necessary to ensure 
an abundant harvest. The atmosphere is an inexhaustible 
store of carbonic acid.” 
“A no less favourable influence than that of lime is exercised 
upon the soil of peaty land by the mere act of burning it , this 
greatly enhances its fertility. We have not long been ac- 
quainted with the remarkable change which the properties of 
clay undergo by burning. The observation was first made in 
the process of analysing the clay silicates. Many of these, in 
their natural state, are not acted on by acids, but they become 
perfectly soluble if heated to redness before the application of 
the acid. This property belongs to potters’ clay, pipe-clay, 
231 . AUCTABICM. 
