Chalk precipitated

It is desired to recover precipitated chalk from the causticising of soda ash. After decanting the liquor from the precipitators the sludge has the composition 5 per cent CaC03, 0.1 per cent NaOH and the balance water. 

CALCIUM CARBONATE CaCOj chunks marble, limestone powder precipitated chalk Builders supplies Drug store... 

For the Mexican boll weevil a specially prepared calcium arsenate containing up to 20 per cent, of arsenic pentoxide is effective. This is prepared by heating together white arsenic and precipitated chalk in the presence of excess air at 650° C. The cotton plant is not injured by this preparation.10 In Peru about 30,000 acres of cotton fields are dusted annually from aeroplanes with calcium arsenate. Acid arsenates of calcium appear to be more toxic to boll weevils and to locusts than the basic arsenates. This is probably because the latter must be partially hydrolysed to compounds giving more soluble arsenic before toxic results are produced.11 The extensive application of such sprays to cotton plants is frequently followed by heavy infestations of the cotton aphis. This appears to be due in the first place to the positive photo-tropism of the winged females to white substances such as the arsenate, chalk or flour. Increase of the aphis population is then aided by the destruction by the spray of the hymenopterous parasites of the aphis.12... 

Method I.—20 gms. (1 mol.) of benzal chloride (see p. 350) are refluxed for 4 hours in an atmosphere of carbon dioxide with 200 c.cs. of water and 40 gms. of precipitated chalk in a round flask heated on an oil bath which is kept at 130°. The whole is then steam distilled in an atmosphere of carbon dioxide (see p. 24). The distillate is extracted with ether, the ether removed on a water bath and the residual benzaldehyde purified by means of its bisulphite compound, as described in Preparation 156. 

A commercial grade of precipitated (not powdered or prepared ) calcium carbonate is satisfactory, if it can be filtered easily. The checkers used Fisher Catalog No. C-62 Calcium Carbonate, u.s.p. (Precipitated Chalk). 

Calcium carbonate, either powdered limestone or precipitated chalk, is used as an anti-acid in dynamite where it serves as a satisfactory stabilizer. Urea is used in dynamite and in celluloid. It reacts with nitrous acid to produce nitrogen and carbon dioxide, and is unsuitable for use in smokeless powder because the gas bubbles destroy the homogeneity of the colloid and affect the rate of burning. The small gas bubbles however commend it for use in celluloid, for they produce an appearance of whiteness and counteract the yellowing of age. 

Write a word equation for the chemical changes that produced the two whiting compounds CaC03 (calcium carbonate), sometimes called precipitated chalk, and Ca(OH)2 (calcium hydroxide), sometimes called slaked lime. After writing the equations, find for each equation the correct classification composition, decomposition, single displacement, or double displacement (see the next subsection, An Artist s Materials and Chemical Change ). 

Synonyms Aeromatt, Albacar, Purecal, Precipitated chalk. 

II. Three parts of precipitated chalk, 2 of sulphur, 6 to 8 of chlorate of potassium. 

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. 

Instead of the rather expensive precipitated chalk, salts of steontia, carbonate of calcium, and the native sulphate of strontium (coelestine), may be used for preparing red fire according to the following receipts ... 

Calcium carbonate fillers are either of ground limestone type or precipitated chalk type. They are inexpensive and have low oil-absorption, which allows considerable freedom in filler levels while keeping the viscosity under control. Relatively coarse particle size fillers ranging from 30 to 100 mesh are used to incorporate high loadings. 

In a tank with a helical coil and a 2-beam stirrer, the validity of this concept was fully confirmed [312]. For dispersions of sand in water ( >, = 5 10 20%) or precipitated chalk in water and in glycerine/water mixtures = 2-12%), the same heat transfer characteristic was obtained as for water alone ... 

Calcium carbonate (precipitated chalk), CaCOs Molecular weight 100.09 colourless, amorphous and heavy powder hardly soluble in water 0.008 grams at 0°C and O.OOSgrams at 20°C per 100... 

Pouret A vessel used lor pouring by the drop. See 62. figures 1-4, Precipitated chalk 1291 An Ingredient in tooth paste. 

Hirkland s Neutral Cerate. Mix together 4 ounces litharge plaster, 14 drachms acetate of lead, and 2 ounces each olivo oil, precipitated chalk, and acetic acid. 

Precipitated calcium carbonate, precipitated chalk, Aero-matt, Albacar, Purecai. Commercial CaCOj produced by chemical means. It is 98-99% pure. The byproduct process, the car bona ti on process, and the calcium chloride process of manuf from limestone are outlined in Kirk-Othmer Encyclopedia of Chemical Technology, vol. 4 (Interscience, New... 

The precipitated chalk—Calcii carbonas prmcipitata (IJ. S. Br.) —is prepared by precipitating a solution of CaCU with one of... 

---