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X\ V. — On the Use of the Spanish Phosphorite as a Manure. 
By Dr. Daubkny. 
In the Memoir " On the Occurrence of Phosphorite in Estre- 
madura," by Captain Widdrington and myself, which was read 
before t!ie (jieological Society, and afterwards pubhshed in the 
"Journal of the Koyal AgricuUnral Society of Ensjland," it was 
pointed out as desirable, that experiments should be undertaken 
with the view of determining, whether this mineral would serve as 
a substitute for bones in agriculture, provided a sufficient supply 
of it should hereafter be obtained at a moderate expense. 
I have therefore been induced to make trial of the above sub- 
stance in the neighbourhood of Oxford, both during the past and 
the present year : on the former occasion, on some land placed at 
my disposal by INIr. Druce of Ensham ; on the latter, on my own 
premises in the Botanic Garden at Oxford. 
The former set of trials, I am sorry to say, led to no result, 
owing to the drj^ness of the season, which caused, not only this, 
but all the other manures which were employed at the same time, 
to prove inefficient; but the experiments undertaken in the Botanic 
Garden, during the present year, appear to lead to more satis- 
factory results. 
In this latter case a selection was made of thirteen different 
plots of ground, all of which might be regarded as in a great 
degree exhausted, having been cropped for ten or eleven successive 
years, without the application of any kind of manure, being the 
same upon which the experiments detailed in my jNIemoir " On 
the Rotation of Crops," published in the last Number of the 
" Philosophical Transactions," had been instituted. The kind 
and quantity of the several mamu'es employed are stated below, 
showing that, whilst in every instance a considerable increase of 
crop was obtained by the addition of these fertilisers, the Spanish 
Phosphorite, especially when its action was quickened by the 
addition of sulphuric acid, proved nearly as efficacious as 
bones themselves, unless indeed when the latter were very finely 
powdered. 
Now, as die Spanish Phosphorite, which appears to act so 
beneficially, is wholly destitute of organic matter, it seems to follow 
that the more valuable portion at least of what is applied to the 
land, when bones are scattered over it, is the phosphate of lime, 
and not, as some have supposed, the oil or the gelatine. 
These experiments also may serve to illustrate the distinction, 
which I have pointed out in the Memoir referred to, between the 
active and the dormant ingredients of a soil. In the case of that 
experimented on in the Botanic Garden, it has been shown in 
page 243 of my Memoir, that the amount of potass, of soda, and 
