Farming of Cornwall. 
439 
be detected by the taste, on the Ijladcs of grass on the northern 
parts of the county, full ten miles from the sea shore. The ap- 
plication of sea-salt is found to act beneficially on soils in souk? 
inland counties, but it is seldom found of any service on those of 
Cornwall. Tiiis seeming anomaly is thus accounted for. There 
cannot be a doubt that most of our plants in Cornwall get quite 
enough of this substance without applying it in the shape of a 
manure ; for when the ocean dashes with violence against the 
rocks, and the crests of the waves are white with foam, the winds 
carry away the spray, drifting it along in clouds and sprinkling it 
over the surface of the land. Potash, on the contrary, is found 
to be a valuable ingredient: it is contained in the granite rocks, 
averaging from 8 to 12 per cent. ; in the felspar, from 15 to 18 
per cent; in the diallage rock, from 6 to 9 per cent. ; in the clay 
slate, from 2-75 and 3 31 per cent. ; in some of our marls, from 
3 to 9 per cent. 
The following analyses of some of them, made by Mr. Hunt, 
Curator of the Museum of Economic Geology, show this, besides 
a large proportion of lime : — 
No. 1. 
No. 2. 
No. 3. 
No. 4. 
Silica .... 
60-9 
63- 
72-20 
68-05 
Alumina 
19-10 
13-10 
14-00 
15-00 
Lime (carbonate) . 
6-15 
15-20 
1-00 
3'15 
Magnesia . 
1-11 
1-0 
0-50 
0-25 
Potash .... 
9-35 
2-23 
1-05 
0-75 
Oxide of iron . 
4-0 
3-35 
lO'O 
1105 
Manganese. 
a trace 
Sulphuric acid . 
•20 
2-12 
Sulphate of lime . 
1-25 
i-75 
No. I is a marl found near Falmouth, used by the proprietor, 
INIr. Thomas Harvey, as a manure. No. 2 is a china stone, found 
on the same spot ; Nos. 3 and 4 are specimens of the Camborne 
marls (17), which have been very extensively used as a manure 
for very many years. Potash is also found in our sea-weed, ac- 
cording to Professor G. Forchhammer, ' in the proportion of from 
5 to 8 per cent., which is used very extensively for manuring the 
land in Cornwall. 
* Potash is not contained to any great degree in the sea — perhaps not 
beyond one grain in 1000. Professor G. Forchhammer stated at the 
meeting of the " British A.ssociatioa " at York, " it was his opinion that 
it is derived from the rocks, being washed into the ocean by the violence 
of rains, and thus, in the case of sea-weed as a manure, we are only 
restoring to the land that of which it had been deprived." 
