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XVI. — On the Chemical Composition of Phosphatic Minerals 
used for Agricultural Purposes. By Dr. Augustus Voelcker, 
F.R.S., Consulting Chemist to the Society. 
In 1861 I published a paper in this Journal on ' The Chemical 
Composition and Commercial Value of Phosphatic Materials 
used for Agricultural Purposes.' In that paper I gave an 
account of all the more important native phosphates which at 
the time were known in commerce, and utilised by manufac- 
turers of artificial manures in the places of, or in addition to, 
cattle-bones, bone-ash from South America, and the refuse bone- 
charcoal or animal-black of sugar refiners. 
The extraordinarily rapid development of the manufacture of 
artificial manures — a branch of industrial pursuit almost un- 
known thirty years ago, — and the large demand for phosphatic 
raw materials, have given a powerful impetus to the search for 
phosphatic minerals in all parts of the world, and led to 
the discovery of numerous deposits of more or less agricultural 
value, which have found their way into vEngland since the pub- 
lication of my paper in 1861. 
In England, coprolite diggings are no longer confined to Cam- 
bridgeshire and Suffolk, but are found also in the adjoining 
counties of Norfolk, Bedfordshire, and Buckinghamshire. 
In France extensive coprolite beds occur in great abundance, 
in the Ardennes and other districts ; and phosphatic nodules and 
fossils useful for agricultural purposes have likewise been lately 
discovered in the south of France as well as in the north. It is 
chiefly from the neighbourhood of Boulo'gne, in the north of 
France, that French coprolites are sent over to England. 
France further supplies English manure-manufacturers with 
phosphorite, large deposits of which were discovered some years 
past in the Department of the Loire and Garonne. This deposit 
is known in commerce as French, or Bordeaux phosphate. It 
resembles in many respects the phosphorite which is found in 
Nassau, in the valley of the Lahn, and which is commercially 
known as German, or Lahn phosphate. 
Russia possesses extensive tracts of land in the Governmental 
department of Koursk, where coprolitic or phosphatic nodules 
occur in immense quantities. Russian coprolite beds are not 
as yet utilised to any extent ; but there can be no doubt that 
they are of great importance to Russian agriculture, and doubt- 
less will be explored at no very remote period. 
