312 Chronicles of Science. | April, 
acid, the natural rock deposit which is imported from Monk’s Island 
and other islets in its neighbourhood. Certain reports, by Liebig, 
Voelcker, and Anderson, of the merits of this substance as a manure, 
which had been drawn up at the request of Messrs. Lawson to be 
used as affidavits in connection with a suit brought against them 
in the Court of Chancery, by Messrs. Thomson, Bonar, and Co., 
agents for the sale of Peruvian guano, have of late been largely used 
by them as a trade advertisement, and a good deal of angry feeling 
has been excited amongst the manufacturers of the cheaper superphos- 
phates by this quotation of ea parte statements on high authority 
against them. The upshot of the discussion, which has been carried 
on chiefly in the columns of the Scottish agricultural journals, appears 
to be the admission, on all hands, that it matters not for the agricultural 
effect of it what may have been the origin, whether mineral or animal, 
of the soluble superphosphate of lime which exists in any manure; 
though as regards the remainder of the substance, which has not been 
acted on by the acid used, but remains in the original condition of 
neutral phosphate, it is a useful manure in the case of the Monk's Island 
deposit, and still more so in the case of bones, but it is entirely 
valueless in the case of the ordinary coprolite, which is the source of 
most of the cheap superphosphates in the market. The tendency of the 
discussion will undoubtedly tend ultimately to bring down the present 
high price charged for the phospho-guano, and assimilate it more 
nearly to the prices charged for ordinary superphosphate. 
The imports of manuring substances during the past year, which 
have been lately published, show a considerable increase under the 
head of bones and guano, but a large diminution under the head of 
nitres. The figures are as follow :— 
Imports. 1862. 1863, 
Tons. Tons. 
Bones, whether burnt or not . 67,230 77,492 
Guano bee eas. esol ecsie ntot ety odnts 141,636 233,574 
SHITE oO 6 6. 9 0 Oo 22,162 20,225 
(OQwlorte mings 5 G 5s ao oO o 39,716 26,990 
3. We come now to such facts of our current agricultural history 
as are classed under the general subject of plant growth. Perhaps the 
leading fact under this head is the growing conviction that, thanks to 
manuring and sheep-feeding on our light soils, and to drainage and 
better tillage on our clays, the fertility of the arable lands of this coun- 
try has of late been rapidly advancing, while that of the pasture lands 
has been stationary. In Gloucestershire a recent inquiry, helped by 
the records of a Cotswold farm which had been kept for nearly a 
hundred years, led clearly to this conclusion. Wheat had on that farm 
doubled its produce per acre since the latter part of last century ; 
barley and oats had not increased correspondingly ; but green crops 
