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XXII. — On the occurrence of Phosphorite in Estremadura. By 
Charles DAUBiiNv, M.D,, F.R.S., F.G.S., Professor of 
Chemistry, &c., Oxford ; and Captain Widdrington, R.N., 
F.R.S., F.G.S., Sac, &c. 
[A paper read before the Geological Society on Feb. 17, 1844.] 
It was generally believed in this country, on the concurrent tes- 
timony of most standard writers on mineralogy, that an extensive 
formation of phosphate of lime existed in certain parts of the 
Spanish province of Estremadura. 
Such an opinion was calculated to excite a lively interest, not 
only in the minds of men of science, but likewise amongst prac- 
tical agriculturists ; for whilst the former would speculate as to the 
causes which could have brought together so large a deposit of 
a material, elsewhere found only in small crystals, except in con- 
nexion with animal matter, and would feel curious to ascertain 
whether the rock in which it occurred contained within itself any 
evidences of the existence of organic life, which might account 
for its formation, the latter would be desirous of learning whether 
such a substance admitted of being employed in husbandry, as a 
substitute for bone-earth now so extensively applied as a manure, 
and if it did, what might be the facilities for procuring it, and the 
means of its conveyance to the coast. 
On inquiring into the sources from which the writers in ques- 
tion had drawn their information with respect to the existence of 
phosphorite in Spain, we soon became satisfied, that the preva- 
lent notions on the subject might be traced altogether to some 
communications relative to it, which had appeared in a Spanish 
periodical, entitled ' Anales de Historia Natural,' published at 
Madrid about the commencement of the present century. 
The first and most important of these is by the celebrated 
chemist Proust, whose name would naturally pass in the world 
of science as a guarantee for any statement which he might put 
forth on his own authority. 
His memoir, however, professes to be little more than the re- 
print of one existing in a periodical now difficult of access, entitled 
' Anales del real Laboratorio de Quimica de Segovia,' which was 
published so long ago as the year 1788, and had also been trans- 
lated in the ' Journal de Physique' of Paris for the same year. 
Nevertheless the reinsertion of the article by the same chemist 
in a journal of the year 1800, might be fairly regarded as an evi- 
dence that its author was still persuaded with regard to its general 
accuracy. * 
* From information received more recently, and still more from an actual 
visit to the place, we became convinced, that Proust's speculations were 
either founded on the early account by Bowles, or had been taken up 
