Charles Everitt, John Smith Flett, and Frederick William Rudler

“ Orthophosphoric acid, H3PO4, a tribasic acid, is obtained by boiling a solution of the pentoxide in water; by oxidizing red phosphorus with nitric acid, or yellow phosphorus under the surface of water by bromine or iodine, and also by decomposing a mineral phosphate with sulphuric acid. It usually forms a thin syrup which on concentration in a vacuum over sulphuric acid deposits hard, transparent, rhombic prisms which melt at 41.7°. On long heating the syrup is partially converted into pyrophosphoric and metaphosphoric acids, but on adding water and boiling the ortho-acid is re-formed. ”

“ Algeria contains important deposits of phosphorite, especially near Tebessa and at Tocqueville in the province of Constantine. Near Jebel Kouif, on the frontier between Algeria and Tunis, there are phosphate workings, as also in Tunis, at Gafsa. The deposits belong to the Lower Eocene, where it rests unconformable upon the Cretaceous. The joint production of Tunis and Algeria in 1907 was not less than a million tons. Phosphates occur also in Egypt, in the desert east of Keneh and in the Dakla oasis in the Libyan desert. ”

“ In northern Estremadura in Spain and Alemtezo in Portugal there are vein deposits of phosphate of lime. As much as 200,000 tons of phosphate have been raised in these provinces, but in 1906 the total production of Spain was only 1300 tons. Large deposits of phosphate occur in Russia, and those in the neighbourhood of Kertch have attracted some attention, it is said that the Cretaceous rocks between the rivers Dniester and Volga contain very large supplies of phosphate, though probably of low grade. ”

“ It has been estimated that 500,000 tons of phosphate were obtained in Aruba, 1,000,000 tons from Curagoa since the deposits were discovered in 1870, and Christmas Island in 1907 yielded 290,000 tons.
In the older formations the phosphates tend to become more and more mineralized by chemical processes. In whatever form they were originally deposited they often suffer complete or partial solution and are redeposited as concretionary lumps and nodules, often called coprolites. ”

“ At the base of the Red Crag in East Anglia, and occasionally at the base of the other Pliocene Crags, there is a “nodule bed,” consisting of phosphatic nodules, with rolled teeth and bones, which were formerly worked as “coprolites” for the preparation of artificial manure Professor R. J. Strutt has found that phosphatized nodules and bones are rich in radioactive constituents, and has brought this into relation with their geological age. ”

“ The soluble trimetallic salts are decomposed by carbonic acid into a dimetallic salt and an acid carbonate. All soluble orthophosphates give with silver nitrate a characteristic yellow precipitate of silver phosphate, Ag3PO4, soluble in ammonia and in nitric acid Since the reaction with the acid salts is attended by liberation of nitric acid: NaH2PO4+3AgNO3=Ag3PO4+NaNO3 +2HNO3, Na2HPO4+3AgNO3=Ag3PO4+2N3NO3+HNO3, it is necessary to neutralize the nitric acid if the complete precipitation of the phosphoric acid be desired. ”

“ From 1500 to 3500 tons of apatite are obtained yearly in Norway from these veins. In Ontario apatite has been worked for a long time in deposits of similar nature. The total output of Canada in 1907 was only 680 tons.
The phosphatic rocks which occur among the sedimentary strata are the principal sources of phosphates for commerce and agriculture. They are found in formations of all ages from the Cambrian to those which are accumulating at the present day. ”