France is rich in mineral phosphates, the chief deposits being the departments of the Pas-de-Calais, Somme, Aisne, Oise in and Meuse, in the north-east, and another group in the departments of Lot, Tarn-et-Garonne and Aveyron, in the south-west: phosphates occur also in the Pyrenees.
In 1892 the phosphates of Tennessee, derived from Ordovician limestones, came into the market.
The Devonian system yields much oil and gas in western Pennsylvania, south-western New York, West Virginia and Ontario; and some of the Devonian beds in Tennessee yield phosphates of commercial value.
The effects of bones are no doubt mainly due to the phosphates they contain, and they are most effectual on dry soils.
Berzelius as to their composition; and his observation that corresponding phosphates and arsenates crystallize in the same form was the germ from which grew the theory of isomorphism which he communicated to the Berlin Academy in December 1819.
But in many regions the soil is deficient in phosphates and nitrates, and large irrigation works can be profitable only in districts where the soil is exceptionally fertile.
Brick clay and limestone are abundant, and there are on the south coast a sand marl rich in phosphates and productive salt deposits.
In 1840 a paper on the phosphates and arsenates, which was clearly unworthy of him, was refused by the Royal Society, and he was so incensed that he published it himself.
There he made analyses of phosphates and phosphites, arsenates and arsenites, confirming the conclusions of J.
C. Harries (Ann., 1903, 328, p. 88) obtained them tolerably pure by the dry distillation of the phosphates of I.