Calcium hydroxide

“ Here the free hydrochloric acid is converted into calcium chloride, and at the same time any ferric chloride present is converted into insoluble ferric hydroxide: 2FeCl3+3CaCO3+3H2O=2Fe (OH) 3+3CaCl2+3CO2. The sulphuric acid present is mostly precipitated as calcium sulphate. The mud thus formed is settled out, and the clear liquor, which is now quite neutral and contains both manganese and calcium chlorides, is mixed with cream of lime and treated by a strong current of air, produced by a blowing-engine. This is done in a tall iron cylinder, say 9 ft. wide and 30 ft. ”

“ The inventor has claimed that his by-product should be valuable and saleable, apparently partly on the ground that it should contain caustic soda. Evidence, however, that a reaction between the calcium oxide or hydroxide and the sodium carbonate takes place in the prevailing conditions is not yet forthcoming, and the probabilities are that such decomposition would not occur unless the residue were largely diluted with water. ”

“ A crystalline amalgam is formed with mercury, which may be distilled in hydrogen at 400° C, but which forms nitride when heated in nitrogen. Heated to redness with potassium or sodium chloride, calcium sets the metal free. Water acts on calcium only very slowly, with the evolution of hydrogen. In liquefied ammonia at-40° C. calcium ammonia is formed—a reddish-brown solid. ”

“ Calcium is not precipitated by sulphuretted hydrogen, but falls as the carbonate when an alkaline carbonate is added to a solution. Sulphuric acid gives a white precipitate of calcium sulphate with strong solutions; ammonium oxalate gives calcium oxalate, practically insoluble in water and dilute acetic acid, but readily soluble in nitric or hydrochloric acid. Calcium is generally estimated by precipitation as oxalate which, after drying, is heated and weighed as carbonate or oxide, according to the degree and duration of the heating. ”

“ Oxalic acid (or an oxalate) , when heated, in the dry state, with oil of vitriol in excess, is converted into carbonate anhydride and carbonic oxide; the former produces a white precipitate with lime water, and the latter, when kindled, burns with a faint blue flame. Of the above tests, solution of sulphate of calcium (vide No. 3) is the most delicate and characteristic.—5. It is distinguished from Epsom salt by its acid reaction, its solubility in rectified spirit, its complete dissipation by heat, and by emitting a slight crackling noise during its solution in water. ”

“ When the hot springs bring up particles of sand, the lime substance incrusts these sand grains, forming globular masses resembling peas, and consequently named pisolite.
In chemical composition, calcite and arragonite consist of a combination of calcium oxide (lime) and carbonic acid, the formula being expressed by CaCO3. Calcium carbonate is insoluble in pure water, but dissolves somewhat freely in water charged with free carbonic acid. It is assumed that a compound is formed, which is known as calcium bi- (or acid) carbonate, is very unstable and can only exist in a state of solution. ”

“ And calcium is present everywhere in nature! Even the purest mineral of potassium, sylvite (the salt, potassium chloride) , contains so much calcium impurity that the RADIOGENIC daughter calcium, produced by the decay of potassium in geologic time, is negligible in comparison. We can say that the bottom of this potassium-40 hourglass has been stuffed with so much sand from the very beginning that the few grains that fall through the waist are lost in the overall mass. This demonstrates that schemes involving the decay of a relatively rare nuclide into a relatively common one are not usable. ”

“ The human body contains a large store of phosphates which are excreted in the urine in combination with sodium and potassium—​and yet these do not draw the calcium from the blood, brain and bones! To be blunt, Nascher’s theory is absurd. The calcium in its various deposits in the body is already combined with phosphoric acid. Why should the phosphorus introduced take calcium from the phosphate radical with which it is already in combination? Nascher asserts that the phosphorus which is introduced as amorphous phosphorus is excreted as amorphous phosphate of lime within twenty-four hours. ”

“ It reddens litmus, and has a sourish taste. It is soluble in 115 parts of cold, but dissolves in 4 parts of boiling water; it dissolves easily in alcohol, less so in ether. It forms well-marked salts; the barium and calcium salt crystallise with one atom of water, the former having the composition BaH4 (C7HO7) 2; the latter, if ammonium meconate is precipitated by calcium chloride, CaH4 (C7HO7) 2; but if calcium chloride is added to the acid itself, the salt has the composition C7H2CaO7 + H2O. If meconic acid is gently heated, it decomposes into carbon dioxide and comenic acid (C6H4O5) . ”

“ 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. ”

“ In some isomorphous groups of minerals replacement takes place to only a limited extent, and the element which is partly replaced always predominates; while in other groups the replacement may be indefinite in extent, and between the ends of the series the different members may vary indefinitely in composition, with no sharp demarcation between species. Thus in the group of rhombohedral carbonates the different species are usually sharply defined. In well-formed crystals of calcite the calcium is replaced by only small amounts of magnesium, iron, lead, &c. ”

“ The whole of the calcium hydrate will now have dissolved. Fifty cubic28 centimeters of the clear liquid should now be withdrawn by a pipette, transferred to a flask, colored with an indicator—either phenol-phthalein, methyl-orange, or litmus may be used—and its alkalinity determined by running in decinormal hydrochloric or sulphuric acid from a burette till the change of color occurs. Each cubic centimeter of the acid corresponds to 0.0028 gramme of calcium oxide, or 0.0037 gramme of the hydrate, Ca (OH) 2. The amount by calculation will give the percentage of real lime present in the sample. ”

“ It is now manufactured by heating lime and carbon in the electric furnace (see Acetylene) . Heated in chlorine or with bromine, it yields carbon and calcium chloride or bromide; at a dull red heat it burns in oxygen, forming calcium carbonate, and it becomes incandescent in sulphur vapour at 500°, forming calcium sulphide and carbon disulphide. Heated in the electric furnace in a current of air, it yields calcium cyanamide (see Cyanamide) .
Calcium carbonate, CaCO3, is of exceptionally wide distribution in both the mineral and animal kingdoms. ”

“ Thomas Willson, a Canadian electrician, tried to make the metal calcium in an electric furnace in his works at Spray, North Carolina, by heating a mixture of lime and coal dust. He thought that the lime (calcium oxide) would act on the coal (carbon) to form calcium and carbon monoxide. He did not succeed in getting calcium, but found in the furnace a brown, crystalline mass, which was decomposed by pouring water on it, yielding an inflammable gas. ”

“ Neither material is altogether free from objection, the cyanamide heating when mixed with other manures and even with soil, and being liable to give off acetylene gas owing to the presence of calcium carbide, whereas the calcium nitrate is a salt which on exposure to a moist atmosphere readily deliquesces. ”

“ From a large quantity of the substance to be examined, the coarse stones, etc., are removed by picking or sifting, and the prepared substance, or in cases where the impurities cannot be separated, the original substance, is treated with sulphuric acid; after it is decomposed, the acid is neutralized with calcium carbonate, and the nitrogen is determined in this mass.
In order to operate rapidly, it is best to use as little sulphuric acid as possible. If too much sulphuric acid is used, necessarily a large amount of calcium carbonate is essential to get it into proper condition for pulverizing. ”

“ These chemists electrolyse either pure calcium chloride, or a mixture of this salt with fluorspar, in a graphite vessel which serves as the anode. The cathode consists of an iron rod which can be gradually raised. On electrolysis a layer of metallic calcium is formed at the lower end of this rod on the surface of the electrolyte; the rod is gradually raised, the thickness of the layer increases, and ultimately a rod of metallic calcium, forming, as it were, a continuation of the iron cathode, is obtained. This is the form in which calcium is put on the market. ”

“ When washing the siliceous residue the filtrate may be tested for calcium by adding ammonia, since that reagent neutralizes the acid which holds the calcium phosphate in solution and causes precipitation; but after the removal of the phosphoric acid in combination with the molybdenum, the addition of an oxalate is required to show the presence of calcium.]
[Note 4: An excess of nitric acid exerts a slight solvent action, while ammonium nitrate lessens the solubility; hence the neutralization of the former by ammonia.] ”

“ To see the metal calcium you must visit a chemical laboratory where, by electrical decomposition or other ingenious process, this elusive element can be induced to part temporarily from its union with the oxygen or other body for which it has so eager an affinity, and to which it returns with such alacrity. Though calcium is certainly a metal, it is very unlike the more familiar metals such as gold or silver, copper or iron. A coin might conceivably be formed out of calcium, but it would have no stability like the coins of the well-known metals. ”

“ Phosphide of calcium is quickly prepared by placing some small pieces of lime in a crucible and making them red-hot; if lumps of dry phosphorus are thrown into the crucible, and the cover placed on quickly, and immediately after the phosphorus, the latter unites with the calcium, and forms a brown substance which produces gaseous phosphide of hydrogen (PH3) when placed in water, and the gas takes fire spontaneously when it comes in contact with the air. ”

“ It is evident that the calcium chloride employed for absorbing the water should be free from lime or other alkalis in order that it may not retain carbonic anhydride. Such calcium chloride may be prepared in the following manner: A perfectly neutral solution of calcium chloride is prepared from lime and hydrochloric acid; it is then carefully evaporated first on a water-bath and then on a sand-bath. When the solution attains a certain strength a scum is formed, which solidifies at the surface. ”

“ Oxalate of calcium falls as a precipitate, and soda remains in solution. This soda is boiled down, and again made use of with fresh sawdust. This recovery of alkali is also practised with the potassium salt which filters through in the last stage. (6) The oxalate of calcium is now decomposed in leaden vessels with sulphuric acid. Sulphate of calcium is precipitated, and oxalic acid is in solution, which is now evaporated, and the acid separates in crystals, which now need only to be recrystallised to make them quite pure, and fit the acid for all the purposes for which it is employed. ”

“ The members of one group combine with the members of the other group with particular ease. As representative of one group may be taken the oxides of the metals, magnesium, sodium, calcium, &c. Representatives of the other group are the oxides formed by the non-metals, sulphur, phosphorus, carbon. Thus, if we take the oxide of calcium, or lime, and bring it into contact with oxides of the second group, combination very readily ensues. For instance, if we mix calcium oxide with oxide of phosphorus they combine with great facility and with the evolution of much heat. ”

“ When pure, calcium is not acted upon at ordinary temperatures by chlorine, though at 100° C. the action is decided. But if the metal contains nitride, chlorine attacks it at the ordinary temperature. At 300° C. calcium ignites and burns brilliantly in oxygen. Gently warmed in air, it burns with brilliant scintillations. It combines with sulphur, with incandescence, at 400° C. At a red heat it unites actively with lampblack, giving a carbide, CaC2. It gives some brittle alloys with magnesium, zinc, and nickel. ”

“ Well-crystallized material, such as Iceland-spar, usually consists of perfectly pure calcium carbonate, but at other times the calcium may be isomorphously replaced by small amounts of magnesium, barium, strontium, manganese, zinc or lead. When the elements named are present in large amount we have the varieties dolomitic calcite, baricalcite, strontianocalcite, ferrocalcite, manganocalcite, zincocalcite and plumbocalcite, respectively.
Mechanically enclosed impurities are also frequently present, and it is to these that the colour is often due. ”

“ Iodine is treated with a small proportion of phosphorus in water, and is thus converted into ‘hydriodic acid,’ hydrate of calcium is then added, and the ‘iodide of calcium’ formed is first fused, and then decomposed by sulphate of potassium into ‘sulphate of calcium,’ which is precipitated, and ‘iodide of potassium,’ which remains in solution, and may be crystallised, as in the other processes. ”