Precipitated carbonate of lime

Mineral Substances.—This class comprises only a few materials, which are used rather as body or coloring matters. Svhnitrctle of bismuth is the. pearl white for the complexion. A less objectionable preparation would be a mixture of native sulphate of baryta and prepared chalk—precipitated carbonate of lime, These latter two, while being as white as the former, are not, like it, discolored by the sulphur fumes in the atmosphere, nor SO particularly injurious to the. skin. ... 

Rose Tooth-powder.—Precipitated carbonate of lime, one pound powdered orris, half a pound rose pink, two drachms. Mix together sift and perfume with attar of roses, one drachm and attar of santal, twenty drops. 

Another Dentifrice,—Precipitated carbonate of lime, One pound powdered borax, half a pound powdered myrrh, four ounces powdered orris, four ounces. Mix, and sift through finest bolting cloth. 

Pearl Powder.—Precipitated carbonate of lime, finely bolted and perfumed. The French add oxides of zinc and bismuth, each one ounce to the pound of chalk. 

Calcium carbonate (1 1) carbonic acid calcium salt 1 1 creta preparada Destab El 70 MagGran CC Micromite Pharma-Carb precipitated carbonate of lime precipitated chalk Vivapress Ca Witcarb. 

After its subsidence, the dear liquid is decanted into another receptacle, in which it is boiled out of contact with the rnr, and stirred at the some time by some mechanical arrangement. - This ebullition expels all the volatile fatty impurities which may be present, and, consequently, the liquid loses both color and odor. As soon as the solution arrives at a density of 14s Twad-dell, it is allowed to cool, when the precipitation of a further portion of sulphate of lime occurB. Should an excess of acid be present, as may be known by its action on tincture of litmus, some chalk or powdered limestone must he added fractionally till the liquid is neutral. After this the boiling is continued as before out of contact with air, during which time the contents of tho vessel must be actively stirred, till the solution marks 37-5° Twaddcll. The sulphate and carbonate of lime are now collected on a filter, and the filtrate reduced by evaporation, till,-upon cooling, it marks 49°, care... 

Opiate Tooth-paste.—Ilouey, powdered orris, and precipitated carbonate cf lime, each half a pound rose pink, two drachms. Rub into paste with simple sirup, and perfume with attars of cloves, nutmeg, and rose, each half an cunce. 

It is most conveniently prepared by adding carbonate of soda to the solution of acid phosphate of lime, obtained by treating bene earth with sulphuric acid. The liquor should be maintained at a boiling temperature and the carbonate of soda must be added as long as effervescence continued, or until the solution has an alkaline reaction. The effervescence is duo to the escape of carbonic acid tbe soda unites with the free phosphoric acid and with a portion of the add of the superphosphate, while at the same time phosphate of lime, or a mixture of this and carbonate of lime, is precipitated. This insoluble matter is removed by filtration, and the liquor is then boiled down and allowed to crystallize. To obtain an additional quantity of the salt from tbe motheT-liquors, it is neocssaiy first to examine if these, manifest an acid or an alkaline reaction. In the first case, more carbonate of soda must he added to restore the alkaline reaction, and the liquor again evaporated and sot aside to crystallize. 

Alumina and Sulphate of Lime.—The alumina obtained from two pounds of alum by precipitation aloug with sulphate of lime, by means of carbonate of lime in suspension, Is washed by decantation and added to one hundred gallons of cane juice. When tho temperature of tire simp has reached 150°, lime is added to neutralization and the juice is then filtered. 

Addition of Lime.—few years ago, Professor Glark of Aberdeen took out a. patent for the purification of watsr. His process consists in the addition of eaustio lime to water, by which the bicarbonate of lime held in solution is decomposed the caustic lime saturates the excess of carhonio acid, and forms carbonate of lime, which is precipitated,... 

OxideofOoba.lt, the ores of which, after grinding and roasting, to drive off as much as possible the excess of arsenic and sulphur, are dissolved in hydrochloric add, sometimes with the addition of a small quantity of nitric acid. The copper, lead, silver, arsenic, antimony, el cetera, are precipitated by sulphide of hydrogen, and to the filtered solution carbonate of lime is added in (he form of chalk, by which all the iron, alumina, and a trace ot cobalt are thrown down, the nickel and cobalt remaining in solution. To this solution which must ho hot and neutral, a solutien of bleaching powder is added in sufficient quantity to precipitate the cobalt, and the menstruum is then well boiled to remove the chlorine as fast as possible. The oxide of nickel is afterwards precipitated from the filtrate by the addition of hydrate of lime, and ebullition. 

Nitrate of Potassa. Called al.so nitre and saltpetre. This salt is spontaneously geuerated in the soil, owing to the action of e atmosphere, and crystamzes upon its sor-face in various parts of the world, especially in the Bast Indies. It is also produced artificially by exposing a mixture of calcareous soil and animal matter to the atmosphere, when nitrate of lime is slowly formed, and is extracted by lixiviation. The liquid is then decomposed by adding carbonate of potash, by which carbonate of lime is precipitated and nitrate of potash remains in solution. 

Kissingen Water. Mix together bicarbonate of soda, I drachm carbonate of lime, 8 scruples precipitated carbonate of iron, 2 scruples common salt, 8 ounces muriate of ammonia, 4 grains sulphate of soda, 8 scruples sulphnfco of magnesia, 2 ounces phosphate of soda, 13 grains phos-... 

When black oxide of iron is dissolved in acids, both protoxide and peroxide are present. The latter may be precipitated by digestion with carbonate of lime, after which the former can be detected in solution. 

Carbonate of lime occurs native, as marble, limestone, chalk, and calcareous spar. It also forms the chief part of shells, and is often found in springs, dissolved by an excess of carbonic acid. When such water, which is very hard water is boiled, the excess of carbonic acid escapes, the carbonate of lime is deposited, and the water becomes, pro tanto, softer. Or, the same effect may be produced by adding just as much lime-water as will neutralise the bicarbonate of lime, when the whole is precipitated as neutral carbonate. CaO, 2 CO, + Ca O = 2 (Ca 0, CO,). 

Lime Soda. Process. Lime (CaO) reacts with a dilute (10—14%), hot (100°C) soda ash solution in a series of agitated tanks producing caustic and calcium carbonate. Although dilute alkaH solutions increase the conversion, the reaction does not go to completion and, in practice, only about 90% of the stoichiometric amount of lime is added. In this manner the lime is all converted to calcium carbonate and about 10% of the feed alkaH remains. The resulting slurry is sent to a clarifier where the calcium carbonate is removed, then washed to recover the residual alkaH. The clean calcium carbonate is then calcined to lime and recycled while the dilute caustic—soda ash solution is sent to evaporators and concentrated. The concentration process forces precipitation of the residual sodium carbonate from the caustic solution the ash is then removed by centrifugation and recycled. Caustic soda made by this process is comparable to the current electrolytic diaphragm ceU product. 

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