Farming of Cornwall. 
441 
64. Limestone. — The supplies of limestone in Cornwall are 
verv inconsiderable, and of an inferior description. The farmers 
are chiefly supplied with it from the coast of Devon. About 
five years since it was ascertained that 30 vessels were regularly 
emploved in carrying limestone from Plymouth to Cornwall, 
and every harbour, nook^ or creek, from the Kame-head to the 
Land's End has had lime-kilns for the purpose of burning it ; 
but the consumption of late has not been so great. The quantity 
of lime used in Cornwall in 1843 was calculated, for the purpose 
of this Report, to be about — 
1,280,000 bushels from Plymouth, 
200,000 bushels raised in Cornwall. 
1,480,000 
Lime is seldom applied in a caustic state except on peaty soils, but 
generally after exposure for several weeks to the air. There is no 
substance the application of which has been so much misunder- 
stood as this. Its effect on our soils is, Jirst, to supply a valuable 
constituent when icanting, it being almost entirely absent from a large 
proportion of our clay-slate rocks ; and next, to liberate tlie silica, 
the potash, and the phosphates* besides the carbonaceous matters 
produced from the decomposition of weeds, roots, &c., to be admi- 
nistered to the wants of vegetation. But by this last operation no 
equivalent was furnished to the land for that removed by the crop ; 
and hence the continuance of the system of liming has been 
proved to be nothing else than a ray)id method of removing those 
ingredients, and thereby of exhausting the soil. Thus, where a 
farmer breaks up an old pasture for wheat, and after burning 
(which is another means of exhaustion), applies from 100 to 150 
bushels of lime per acre, the crop is considerably benefited by 
the lime rendering soluble the nutritive ingredients in the soil — 
not always the supplying of materials which the soil might re- 
quire. For very many years, this has been the custom in Corn- 
wall in preparing for the wheat tillage; and for several years it 
was observed that those who carried the most lime on their estates 
raised the greatest crops, but now those same parties complain 
of the impurity of the lime, because it does not produce the same 
effect as formerly — not understanding the simple fact, that its 
repeated application has exhausted the soil of those constituents 
on which it formerly acted. 
65. Iron. — This mineral is found abundantly in the form of proto 
and peroxides in a great many soils. The sulphurets and proto- 
sulphates are also occasionally present. The rapid disintegration 
• See Professors Brand and Playfair's lectures, delivered before the 
members of the Royal Agricultural Society in 1843 and 1844. 
