Florida phosphates are found in the forms of soft phosphate, a whitish product somewhat resembling clay and largely contaminated with it; pebble phosphate, consisting of hard pebbles; rock or boulder phosphate, consisting as the name implies of rocks or boulders. Soft phos phate contains from 18 to 30 per cent of phos phoric acid and on account of its being more easily ground than most of these rocks is ap plied to the land without being first converted into a superphosphate. Pebble rock constitutes the major portion of the Florida phosphate. It contains from 20 to 40 per cent of the phos phoric acid, being very variable in compositicL Rock or boulder phosphate is much more = form in composition than the other kinds, isc there is less of it. It contains about 40 pe cent of phosphoric acid.
Tennessee phosphate differs from the Car: lina and Florida phosphate in that it does m.-r exist as nodules, pebbles or boulders, but r, veins and pockets and does not need to be washed previous to its treatment. It coritai.-, from 30 to 35 per cent of phosphoric acid Utah, Wyoming and Montana contain de posits of mineral phosphate interbedded arnm.: limestones and shales with amount estinaa: at nearly six billion tons. At present they an not producing much, the output in 1916 be only 1,700 tons. This is because of the local demand for fertilizer and high cost o.f transportation to distant markets. In Ic there is high grade phosphate on both sides Blackfoot River, in Fort Hall Indian Reserv-4 don, near Montpelier and north of Bear Lake. In Utah the deposits are in the IA'asatth Oquirrh and Uinta ranges and east of Her Lake. In western Wyoming the deposits an mostly in Wind River, Gros Ventre, Salt River and Owl Creek ranges, and in Montana tit deposits are near Ellison, Garrison, burg and Melrose. The material is an even-bedded gray to brown or black oolitiz rock, closely resembling limestone, and emits az a fetid odor when struck with a hammer Weathered surfaces have a light-bluish or white coating commonly in reticulated pattern_ Many of these deposits carry 65 to 81 per cent of tricalcium phosphate and are four to six feet thick. On places there are two or more beds and they extend for many miles. Most of the areas underlain by the thicker beds are govern ment land, parts of which have been withdraw from entry in order to preserve them for a reserve which can be developed for the use of the people.
Basic slag, or as it is also called, phosphate slag, or Thomas phosphate, is a by-product in the manufacture of steel from pig iron rich in phosphorus. The phosphoric acid present is in the form of tetracalcium phosphate (CaO).Pr
O.. It also contains calcium, magnesium. aluminum, iron manganese, silica and sulphur On account of the presence of iron and alum inum and because its phosphoric acid is more readily soluble than the tncalcium phosphate. the ground slag is applied directly to the solid without treatment with acid. It is produced in large quantities in England, Germany and France.
Superphosphate Fertilizers.— In order to render more readily available to plants the phosphoric acid contained in bone and mineral phosphates, the raw material, purified by being washed and finely ground, is treated with sul phuric acid. This results in a replacement of phosphoric acid by sulphuric acid with the formation of monocalcium phosphate and cal cium sulphate, with a smaller amount of dical cium phosphate, according to the reactions: Ca, (P 04) + 2F1, SO.---= Ca IL (P O.) 2+ 2CaSO, and Ca, (P O.), + O. H, (P 04), + Ca S 04.
The tricalcium phosphate, being in excess of the sulphuric acid used, a part of it remains unchanged.
In the treatniem of phosphate rock part of the sulphuric acid is consumed in acting upon the impurities present, which usually consist of calcium and magnesium carbonates, iron and aluminum phosphates and calcium chloride or fluoride, converting the bases into sulphates and freezing carbon dioxide. water, hydrochloric acid and hydrofluoric acid. The resulting super phosphate is therefore a mixture of monocal cium phosphate, dicalcium phosphate, trical ciuin phosphate, calcium sulphate and iron and aluminum phosphates.
In the superphosphates made from bone the iron and aluminum sulphates do not exist in any considerable amounts. However, as long as the phosphoric acid remains in the form of monocalcium phosphate the value of a pound of available phosphoric acid in the two kinds of fertilizer is the same, but the remaining tricalcium phosphate in the bone superphos phates has a greater.value as before explained.
The superphosphates made from animal bone contain about 12 per cent available phosphoric acid and 3 or 4 per cent of insoluble phos phoric acid. They also contain sonic nitrogen. Bone-ash and bone-black superphosphates con tain practically all of their phosphoric acid in an available form, but they contain little or no nitrogen. South Carolina rock superphos phate contains from 12 to 14 per cent available phosphoric acid, including from 1 to 3 per cent reverted phosphoric acid. The best Florida superphosphates contain from 17 per cent downward of available phosphoric acid, part of which is reverted. The Tennessee superphosphates vary from 14 to 18 per cent available phosphoric acid.