Calcium phosphate

“ It is the chief mineral constituent of bones of animals, and bone ash is therefore nearly pure calcium phosphate.
Preparation. Phosphorus is now manufactured from bone ash or a pure mineral phosphate by heating the phosphate with sand and carbon in an electric furnace. The materials [Pg 240] are fed in at M (Fig. 70) by the feed screw F. The phosphorus vapor escapes at P and is condensed under water, while the calcium silicate is tapped off as a liquid at S. The phosphorus obtained in this way is quite impure, and is purified by distillation.
Fig. 70
Explanation of the reaction. ”

“ In addition to free phosphoric acid, iron phosphate is separated, which gradually passes into an insoluble form by the abstraction of water due to the crystallization of the gypsum. The alumina present [Pg 141] in a superphosphate seems to have no direct influence on the process of reversion. Its phosphate salt is not acted on by the acid calcium phosphate. Even when a superphosphate solution is treated with alum no precipitation is produced, except on warming, and this disappears when the mass is again cold. ”

“ Since the calcium phosphate of the apatite is also insoluble in ammoniacal solutions, this procedure cannot be applied directly. The separation of the phosphoric acid from the calcium must first be accomplished by precipitation in the form of ammonium phosphomolybdate in nitric acid solution, using ammonium molybdate as the precipitant. The "yellow precipitate," as it is often called, is not always of a definite composition, and therefore not suitable for direct weighing, but may be dissolved in ammonia, and the phosphoric acid thrown out as magnesium ammonium phosphate from the solution. ”

“ DETERMINATION OF PHOSPHORIC ANHYDRIDE IN APATITE The mineral apatite is composed of calcium phosphate, associated with calcium chloride, or fluoride. Specimens are easily obtainable which are nearly pure and leave on treatment with acid only a slight siliceous residue. ”

“ Sulphates, nitrates and phosphates generally require the application of more or less heat, when they too are rapidly and energetically decomposed. Calcium phosphate is attacked in the cold like lime, giving out a brilliant white light, and producing calcium fluoride and gaseous oxyfluoride of phosphorus, POF3. Calcium carbonate also becomes raised to brilliant incandescence when exposed to fluorine gas, as does also normal sodium carbonate ”

“ As calcium phosphate is necessary to a fertile soil, bone-dust and mineral phosphates of calcium are sold commercially as fertilizers. Bones have for many years been an important form of phosphate manure. They generally are first boiled or steamed. Bone-phosphates, being slow-acting fertilizers, should be used finely ground and as a permanent benefit to the soil rather than as direct plant-food. Phosphates associated with organic matter decompose more quickly than purely mineral phosphates do. They therefore are more readily available fertilizers. ”

“ To sum up, we see that, whether from food or from sea-water, calcium sulphate will tend to pass but little into solution in the albuminoid substances of the body: calcium carbonate will enter more freely, but a considerable part of it will tend to remain in solution: while calcium phosphate will pass into solution in considerable amount, but will be almost wholly precipitated again, as the albumin becomes broken down in the normal process of metabolism. ”

“ It is usually made by treating calcium phosphate with concentrated sulphuric acid. The calcium sulphate produced in the reaction is nearly insoluble, and can be filtered off, leaving the phosphoric acid in solution. Very pure acid is made by oxidizing phosphorus with nitric acid. It forms large colorless crystals which are exceedingly soluble in water. Being a tribasic acid, it forms acid as well as normal salts. Thus the following compounds of sodium are known:
These salts are sometimes called respectively primary, secondary, and tertiary phosphates. ”

“ With calcium and oxygen it forms the exceedingly hard phosphate of calcium that gives the bones their rigidity.
No one appears to be perfectly sure what part it plays in the other tissues of the body. Something very forcible, certainly, for whenever sufficient is not present we grow listless; and nothing tones up the system, in some states of low health, like a course of phosphorus medication. If phosphorus is not precisely, as many people suppose, the element that gives man his intellectual power, it is absolutely essential to a high degree of nervous efficiency. ”

“ Therapeutics.—The phosphorus used in the British pharmacopoeia is obtained from calcium phosphate, and is a waxlike non-metallic substance soluble in oils and luminous in the dark. There are various medicinal preparations. In young animals phosphorus has a remarkable influence on the growth of bone, causing a proliferation of the jelly-like masses and finally a deposit in them of true bony material. ”

“ In fact, sodium and phosphate are more effectively administered as neutral or acid phosphate. It is evident that sodium glycero­phosphate is a superfluous pharmaceutical preparation, particularly when the difficulty of obtaining a pure product and its high price is considered. So far as its calcium value is concerned, calcium glycero­phosphate has no advantages over such calcium salts as the carbonate, phosphate, lactate, or chlorid. ”

“ APATITE, a widely distributed mineral, which, when found in large masses, is of considerable economic value as a phosphate. As a mineral species it was first recognized by A.G. Werner in 1786 and named by him from the Greek ἀπατᾶν, to deceive, because it had previously been mistaken for other minerals, such as beryl, tourmaline, chrysolite, amethyst, &c. Although long known to consist mainly of calcium phosphate, it was not until 1827 that G. Rose found that fluorine or chlorine is an essential constituent. ”

“ It most abundantly occurs as apatite, a mineral consisting of calcium phosphate, with small quantities of calcium fluoride or calcium chloride. This apatite, or phosphorite, is found in certain parts of the world in large masses; but as a rule, it only occurs in small quantities in most rocks. It may be stated that the older rocks are, as a general rule, richer in it than those of more recent formation; and Daubeny has drawn attention to this fact as furnishing a useful guide in estimating the probable richness of a soil in phosphoric acid. ”

“ A part of the iron sulfate formed reacts with the acid calcium phosphate present to produce a permanent jelly-like compound, difficult to dry and handle. As much as two per cent of iron phosphate, however, may be present without serious interference with the commercial handling of the product. By using more sulfuric acid as much as four or five per cent of the iron phosphate can be held in solution. Larger quantities are very troublesome from a commercial point of view. ”

“ Most beautiful osmotic cells may be produced by dropping a fragment of fused calcium chloride into a saturated solution of potassium carbonate or tribasic potassium phosphate, the calcium chloride becoming surrounded by an osmotic membrane of calcium carbonate or calcium phosphate. ”

“ The pieces were dried, ashed, the ash dissolved in dilute nitric acid, and the phosphates precipitated by ammonium molybdate. In the skin before puering no phosphates were present, but in the skin after puering there was a small amount, though not sufficient to weigh.
The action of ammonium phosphate on the lime in the skin is very small. A skin was treated with a 0·1 per cent. solution of ammonium phosphate at 100° F. for one hour. The CaO in the dry skin was estimated, and found to be—
A considerable amount of calcium phosphate was found in the skin after the experiment. ”

“ Mineral matter is quite as necessary for plant as for animal life, and is therefore present in all food, except in the case of some highly-prepared ones, such as sugar, starch and oil. Children require a good proportion of calcium phosphate for the growth of their bones, whilst adults require less. The outer part of the grain of cereals is the richest in mineral constituents, white flour and rice are deficient. Wheatmeal and oatmeal are especially recommended for the quantity of phosphates and other salts contained in them. ”

“ These are often made and sold by ignorant men, whose sole object is to make money. Calcium superphosphate and acid calcium phosphate very frequently contain arsenic, and as the cheap commercial qualities are often used there is danger in this direction. A good formula for baking powder is, tartaric acid 8 ozs., sodium bicarbonate 9 ozs., rice flour 10 to 20 ozs. ”

“ Look for any flame. H2SO4 acts very strongly on KClO3. What is set free? From this fact explain the combustion in water.
199. Occurrence.—P is very widely disseminated, but not abundant, and is found only in compounds, the chief of which is calcium phosphate Ca3 (PO4) 2. It occurs in granite and other rocks, as the mineral apatite, in soils, in plants, particularly in seeds and grains, and in the bones, brains, etc., of vertebrates. From the human system it is excreted by the kidneys as microcosmic salt, HNaNH4PO4; and when the brain is hard- worked, more than usual is excreted. ”

“ Phosphate of potassium is the mineral basis of muscle tissue, phosphate of lime with a small amount of magnesium phosphate the basis of bones, and phosphate of ammonium the bases of nervous tissue. There is a sufficient quantity of phosphate in all healthy foods. When the milk fed to nurslings, however, is greatly thinned with water instead of firm muscle fibers and solid lymph glands we find loose and spongy tissues. This is a scrofulous condition.
In the formation of healthy bones and teeth, calcium fluoride is essential. ”

“ In each case the water in the final product is probably united as crystal water with the calcium salts produced. The monocalcium salt formed in the first reaction is soluble in water and the dicalcium salt in the second reaction in ammonium citrate. Where fertilizers are to be transported to great distances there is a considerable saving of freight by the use of such a high-grade phosphate, which may, at times, contain over forty per cent of available acid. The phosphoric acid used is made directly from the mineral phosphate by treating it with an excess of sulfuric acid. ”

“ It dissolves readily in water, the solution having an acid reaction. The artificial manure known as “superphosphate of lime” consists of this salt and calcium sulphate, and is obtained by treating ground bones, coprolites, &c., with sulphuric acid. The di-calcium salt, Ca2H2 (PO4) 2, occurs in a concretionary form in the ureters and cloaca of the sturgeon, and also in guano. It is obtained as rhombic plates by mixing dilute solutions of calcium chloride and sodium phosphate, and passing carbon dioxide into the liquid. ”

“ Manufacture of phosphorus with the assistance of electricity. Readman and Parker have recently devised a process for the manufacture of phosphorus on a large scale in a continuously working apparatus by means of a powerful electric current, such as is yielded by a larger dynamo. The mixture used for the operation differs from the ordinary one of calcium phosphate and charcoal, in that it contains in addition a slag-forming body—a flux—silicic acid (quartz sand) being at first used for the purpose. ”

“ The acid renders it available as a manure by converting the calcium phosphate, Ca3P2O8, that it contains into the soluble monocalcium salt, CaH4P2O8, or “superphosphate.” The phosphate thus produced forms an efficacious turnip manure, and is quite equal in value to that produced from any other source. The Chloritic Marl in the Wealden district furnishes much phosphatic material, which has been extensively worked at Froyle. In the vicinity of Farnham it contains a bed of “coprolites” of considerable extent and 2 to 15 ft. in thickness. ”

“ To prevent the melting of the lead the pans are bricked in under a very flat arch, so that the fire gases are forced to pass close over the liquor, the pans being kept constantly full. When crystallization is complete the liquor is drawn off and the pans are refilled.
In the manufacture of phosphorus there is left after every distillation a residue of basic calcium phosphate, and it is advisable to decompose it with hydrochloric acid, this being effected in a vat lined with lead or coated with paraffine. ”

“ The mineral brushite, CaHPO4·2H2O, which is isomorphous with the acid arsenate pharmacolite, CaHAsO4·2H2O, is an acid phosphate, and assumes monoclinic forms. The normal salt may be obtained artificially, as a white gelatinous precipitate which shrinks greatly on drying, by mixing solutions of sodium hydrogen phosphate, ammonia, and calcium chloride. Crystals may be obtained by heating di-calcium pyrophosphate, Ca2P2O7, with water under pressure. ”

“ Estimation of the Lime and Magnesia.—The filtrate and washings from the first precipitation, (paragraph 41,) of iron and alumina in the method of Krug and McElroy, above described, are collected and sufficient ammonium oxalate is added to precipitate the calcium. The precipitated calcium is very fine and should be collected on a gooch, under pressure. The filtrate and washings from the calcium precipitate are again collected, and a solution of sodium phosphate added to precipitate the magnesia. ”

“ The pulverised mixture of the phosphate and oxide is introduced at the upper end of an inclined rotating furnace, by means of a hopper and screw feed; fuel is fed in at the lower end, and an outlet is provided for the periodic removal of the calcium titanate, etc., formed. The silica and alumina of the impure phosphate, together with the titanium dioxide introduced, displace the phosphorus pentoxide, which, being volatile, escapes continuously through a special pipe; there is left a mixture of silicate, aluminate and titanate of calcium, which may be used as a source of titanium compounds. ”