438 
Farmhuj of Corracalh 
Cornwall proceeds from the want of sufficient capital. The tur- 
nip husbandry is the onlj true system of improving the soil and 
increasing the profits on the farm ; but a larger capital would be 
requisite than is now commonly employed where so large a por- 
tion of the land is brought round to the reproduction of corn by 
means of rest instead of green crops. In these cases it would be 
well if the farmer would consider the means at his disposal pre- 
vious to entering on an estate, and not occupy more land than 
he can successfully cultivate. There is no mistake m.ore common 
or more injurious than the supposition, that the more land a man 
occupies the greater must be his profits. The profit does not 
arise from the land itself, but from the mode of cultivation ; and 
we could adduce many instances around us to prove that farmers 
properly managing small holdings are improving the soil and 
realizing fair profits ; whilst others, on the contrary, on large 
farms, by bad management, are ruining their farms and them- 
selves at the same time. 
Manures. 
58. It Is an ascertained fact, that the food of vegetables consists 
of the materials of which they art; composed. These are of two kinds 
— inorganic and organic. The first are silica, perhaps ahimina, pot- 
ash, soda, magnesia, lime, iron, sulphuric acid, phosjihoric acid and 
chlorine. The organic are oxygen, hydrogen, carbon, and a little 
nitrogen. Our inquiry will not extend any further into the phi- 
losophy of the food of plants than to ascertain what sources Corn- 
wall has in her own domain to furnish those materials. 
59. Silica. — All our rocks have a large per centage of silica. 
The granite contains 70 per cent., the slates from 70 to 80 per 
cent., and the serpentine 45 per cent., which uniting with the 
basis of potash, soda, lime, and magnesia, form silicates, in which 
state of combination it exists in the substances of all livinjj vese- 
tables, particularly in the grasses, and in the outer part of the 
leaves and stalks. 
GO. Alumina. — This mineral is the principal ingredient of all 
clayey soils, which increase in tenacity in proportion to the q*uan- 
tily they contain. Its average proportion in the clay-slate rocks 
varies from 4 to IG per cent., and in the granite from 15 to 20 
per cent. 
61. Potash and Soda. — Professor Liebig stated at the meeting 
of the British Association at York, " that he invariably found a 
large proportion of soda in vegetables growing near the sea coast ; 
proving that plants could substitute soda for potash without 
injury to their growth." " No plants," he also said, " were found- 
in w hich there was no potash, l)ut there were very many which 
contained no soda." The salt of the ocean (chloride of soda) can 
