Cadmium hydroxide, Cd(OH) 2, is obtained as a white precipitate by adding potassium hydroxide to a solution of any soluble cadmium salt.
Normal cadmium carbonates are unknown, a white precipitate of variable composition being obtained on the addition of solutions of the alkaline carbonates to soluble cadmium salts.
The molybdates may be recognized by the fact that they give a white precipitate on the addition of hydrochloric or nitric acids to their solutions, and that with reducing agents (zinc and sulphuric acid) they give generally a blue coloration which turns to a green and finally to a brown colour.
With ferric chloride it gives a violet coloration, and with bromine water a white precipitate of tribromphenol.
If excess of a mineral acid be added to a solution of an alkaline thiogermanate a white precipitate of germanium disulphide, GeS2, is obtained.
The germanium salts are most readily recognized by the white precipitate of the disulphide, formed in acid solutions, on passing sulphuretted hydrogen.
The white precipitate formed by cold hydrochloric acid is boiled with water, and the solution filtered while hot.
The white precipitate consists of lead sulphate.
To the filtrate add ammonia in excess: a white precipitate indicates bismuth; if the solution be blue, copper is present.
A white precipitate rapidly turning brown indicates manganese.
The solution with ammonium sulphide gives a white precipitate of zinc sulphide.
The solution free from barium is treated with ammonia and ammonium sulphate, which precipitates strontium, and the calcium in the solution may be identified by the white precipitate with ammonium oxalate.
Bromine water in dilute aqueous solution gives a white precipitate of tribromophenol-bromide C 6 H 2 Br 3.
The oxychloride comes down as an amorphous white precipitate.
It is produced by the addition of a solution of lead salt to an excess of ammonium carbonate, as an almost insoluble white precipitate.
Lead sulphate, PbSO 4, occurs in nature as the mineral anglesite (q.v.), and may be prepared by the addition of sulphuric acid to solutions of lead salts, as a white precipitate almost insoluble in water (1 in 21,739), less soluble still in dilute sulphuric acid (1 in 36,504) and insoluble in alcohol.
The normal ortho-phosphate, Pb3(P04)2, is a white precipitate obtained by adding sodium phosphate to lead acetate; the acid phosphate, PbHPO 4, is produced by precipitating a boiling solution of lead nitrate with phosphoric acid; the pyrophosphate and meta-phosphate are similar white precipitates.
The borate, Pb 2 B 6 0 1 u 4H20, is obtained as a white precipitate by adding borax to a lead salt; this on heating with strong ammonia gives PbB2044H2.
(4) Orthostannic acid is obtained as a white precipitate on the addition of sodium carbonate or the exact quantity of precipitated calcium carbonate to a solution of the chloride.
Zinc sulphide, ZnS, occurs in nature as blende (q.v.), and is artificially obtained as a white precipitate by passing sulphuretted hydrogen into a neutral solution of a zinc salt.
Aqueous alcohol becomes turbid when mixed with benzene, carbon disulphide or paraffin oil; when added to a solution of barium oxide in absolute alcohol, a white precipitate of barium hydroxide is formed.
With excess of water, it gives a white precipitate of the oxychloride, BiOC1.
The basic carbonate, 2(B10) 2 CO 3 4H 2 O, obtained as a white precipitate when an alkaline carbonate is added to a solution of bismuth nitrate, is employed in medicine.
Pertantalic acid, HTaO 4, is obtained in the hydrated form as a white precipitate by adding sulphuric acid to potassium pertantalate, K 3 Ta0 5.
Acetylene is readily soluble in water, which at normal temperature and pressure takes up a little more than its own volume of the gas, and yields a solution giving a purple-red precipitate with ammoniacal cuprous chloride and a white precipitate with silver nitrate, these precipitates consisting of acetylides of the metals.
After neutralization, it gives a white precipitate with silver nitrate.
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.
It may be readily recognized by the white precipitate which it forms when passed through lime or baryta water.
Silver cyanide, AgNC, is formed as a white precipitate by adding potassium cyanide to silver nitrate solution; or better, by adding silver nitrate to potassium silver cyanide, KAg(NC) 2, this double cyanide being obtained by the addition of one molecular proportion of potassium cyanide to one molecular proportion of silver nitrate, the white precipitate so formed being then dissolved by adding a second equivalent of potassium cyanide.
Silver nitrate gives a white precipitate with cyanides, soluble in excess of potassium cyanide.
The magnesium salts may be detected by the white precipitate formed by adding sodium phosphate (in the presence of ammonia and ammonium chloride) to their solutions.
The same reaction is made use of in the quantitative determination of magnesium, the white precipitate of magnesium ammonium phosphate being converted by ignition into magnesium pyrophosphate and weighed as such.
To purify the oxide, it is dissolved in dilute hydrochloric acid until the acid is neatly neutralized, the solution is cooled, filtered, and baryta water is added until a faint permanent white precipitate of hydrated barium peroxide appears; the solution is now filtered, and a concentrated solution of baryta water is added to the filtrate, when a crystalline precipitate of hydrated barium peroxide, Ba0 2 8 H 2 0, is thrown down.
Thallous chloride, T1C1, is readily obtained from the solution of any thallous salt, by the addition of hydrochloric acid, as a white precipitate similar in appearance to silver chloride, like which it turns violet in the light and fuses below redness into a (yellow) liquid which freezes into a horn-like flexible mass.
Urea may be recognized by its crystalline oxalate and nitrate, which are produced on adding oxalic and nitric acids to concentrated solutions of the base; by the white precipitate formed on adding mercuric nitrate to the neutral aqueous solutions of urea; and by the so-called "biuret" reaction.
Manganous hydroxide, Mn (OH) 2, is obtained as a white precipitate on adding a solution of a caustic alkali to a manganous salt.
By the addition of caustic soda to cerous salts, a white precipitate of cerous hydroxide is formed.
Calcium chloride gives a white precipitate of calcium tartrate in neutral solutions, the precipitate being soluble in cold solutions of caustic potash but re-precipitated on boiling.
It is obtained as a yellowish white precipitate by mixing solutions of a bromide and a silver salt.
In solution, sulphates are always detected and estimated by the formation of a white precipitate of barium sulphate, insoluble in water and all the common reagents.
The monohydrate also results as a white precipitate when concentrated sulphuric acid is added to a saturated solution of ferrous sulphate.
An acid arsenate, 2Fe2(HAsO4)3.9H20, is obtained as a white precipitate by mixing solutions of ferric chloride and ordinary sodium phosphate.
Ferrous salts also give a bluish white precipitate with ferrocyanide, which on exposure turns to a dark blue; ferric salts are characterized by the intense purple coloration with a thiocyanate.
milky white precipitate.
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