Potassium chloride

“ At 32° F. it is brittle, like glass; at 59° it is soft and malleable; at 144° it becomes liquid. Potassium is widely diffused in the vegetable, animal and mineral kingdoms. Some of the more important potassium compounds are caustic potash (the hydroxide) , the carbonate, the bicarbonate; also potassium chloride, bromide, iodide, nitrate (saltpeter) , sulphate, chlorate, cyanide etc. Of these iodide, bromide and chlorate are used for medicines, the others being employed more or less in the arts. ”

“ The Diaphragm process is probably the only one employed at present for the decomposition of potassium chloride, and it is also used for sodium chloride. A hot, concentrated solution of the alkaline chloride is treated by the electric current in large iron tanks which at the same time serve as cathodes. The anodes are made of retort-carbon or other chlorine-resisting material, and they are mounted in cells which serve as diaphragms. The material of these cells is usually cement, mixed with certain soluble salts which impart sufficient porosity to the material. ”

“ When hot saturated solutions of sodium nitrate and potassium chloride are brought together, sodium chloride precipitates and can be filtered off, leaving potassium nitrate in solution, together with some sodium chloride. On cooling, potassium nitrate crystallizes out, leaving small amounts of the other salts in solution.
Potassium nitrate is a colorless salt which forms very large crystals. It is stable in the air, and when heated is a good oxidizing agent, giving up oxygen quite readily. Its chief use is in the manufacture of gunpowder. ”

“ A solution of chloride of lime marking 18° or 20° Baumé, is to be set upon the fire in a lead or cast iron pot, and when it begins to get hot, there is to be dissolved in it, a quantity of chloride of potassium sufficient to raise the hydrometer 3 or 4 degrees. It must be then concentrated as quickly as possible till it marks 30° or 31°, taking care that it does not boil over by the sudden extrication of oxygen. The concentrated liquor is set aside to crystallize in a cool place; where a deposit of chlorate of potash forms, mixed with chloride of potassium. ”

“ The reaction may be written for our purpose in the form: KClO3 = KCl+3O; in case a the oxygen is liberated as such; in case b it oxidizes the hydrochloric acid to water and chlorine oxides. The equation shows that one KCl is equivalent to 3O, and hence if x grams of chlorate yields y grams of chloride, then the ratio KCl:O = y/ (x–y) . Taking O as 16 and the experimental value of x and y, Stas obtained KCl:O = 74.9502. To find the ratio of Ag:KCl, a known weight of silver was dissolved in nitric acid and the amount of potassium chloride necessary for its exact precipitation, was determined. ”

“ He placed the gelatine solution of a salt, potassium chloride, for example, in a horizontal glass tube, and found the rate of migration of the potassium and chlorine ions by observing the speed at which they were replaced when a coloured anion, say, the Cr2O7 from a solution of potassium bichromate, entered the tube at one end, and a coloured cation, say, the Cu from copper sulphate, at the other. The coloured ions are specifically slower than the colourless ions which they follow, and in this case it follows that the coloured solution has a 864 higher resistance than the colourless. ”

“ The most important of the halide salts is the chloride which, in the hydrated form, has the formula MgCl2·6H2O. It may be prepared by dissolving the metal, its oxide, hydroxide, or carbonate in dilute hydrochloric acid, or by mixing concentrated solutions of magnesium sulphate and common salt, and cooling the mixture rapidly, when the less soluble sodium sulphate separates first. It is also formed as a by-product in the manufacture of potassium chloride from carnallite. The hydrated salt loses water on heating, and partially decomposes into hydrochloric acid and magnesium oxychlorides. ”

“ Chemically pure chloride of potassium is most conveniently prepared from the pure perchlorate by heating it in a platinum basin at the lowest temperature and then fusing the residue in a well covered platinum crucible. The fused product solidifies on cooling into a colourless glass. ”

“ It requires more than 1200 parts of water for its solution: for its perfect purification, it should be heated with a solution of chloride of potassium, the insoluble portion separated whilst the liquid is lost, and the peculiar salt allowed to deposit as the temperature falls. When heated, it behaves like the salt of silver. ”

“ Carbonate of potassium frequently contains an undue quantity of water, as well as silicic acid, sulphates, and chlorides. The water may be detected by the loss of weight the salt suffers when heated; the silica, by adding to it hydrochloric acid in excess, evaporating to dryness, and igniting the residuum, by which this contamination is rendered insoluble; the sulphates and chlorides may be detected by adding nitric acid in excess, and testing the liquid with nitrate of silver and chloride of barium. If the former produces a white precipitate, a chloride is present ”

“ At room temperature it has a vapor pressure of 24 mm. of mercury. It thus lies, in persistency, between such gases as phosgene on the one hand, and mustard gas on the other, but so much closer to phosgene that it is placed in the phosgene group.
Chloropicrin is a very stable compound and is not decomposed by water, acids or dilute alkalies. The reaction with potassium or sodium sulfite, in which all the chlorine is found as potassium or sodium chloride, has been used as an analytical method for its quantitative determination. ”

“ Chlorine, although one of the most widely distributed elements known to chemists, is never found in the free condition in nature; it exists in enormous quantities in combination with sodium, potassium, calcium, magnesium, etc. As sodium chloride, common salt, it occurs in practically inexhaustible quantities in sea water together with smaller quantities of other chlorides. ”

“ If chloride of spiroil be melted with potassium by the application of a very gentle heat, violent evolution of heat and light suddenly takes place. A portion of the chloride of spiroil is decomposed thereby; carbon is deposited, whilst another portion unites with the potash which has been formed. If the remaining mass be dissolved in water, and the solution decomposed by nitric acid, pure chloride of spiroil is precipitated. If this same fluid be filtered, nitrate of silver gives a large precipitate of chloride of silver. ”

“ He says “If I can do that, I can make pictures ad libitum.” With this object in view he coated paper with silver chloride. He exposed it then in the camera, fixed it in a solution of salt—common salt or iodide of potassium—and when he got through the picture was a [36] permanent one, because the iodide of potassium dissolved out the white parts that were not affected by the light. ”

“ Chlorine does not occur free in nature, but its compounds are widely distributed. For the most part it occurs in combination with the metals in the form of chlorides, those of sodium, potassium, and magnesium being most abundant. Nearly all salt water contains these substances, particularly sodium chloride, and very large salt beds consisting of chlorides are found in many parts of the world. ”

“ Chlorine gas, prepared in the ordinary manner, is slowly passed into a cold solution of ferrocyanide of potassium, 1 part, in water, 10 parts, with constant agitation, until the liquid appears of a deep reddish-green colour, or of a fine red colour by transmitted light, and ceases to give a blue precipitate, or even a blue tinge, to a solution of ferric chloride, an excess of chlorine being carefully avoided; the liquor is next evaporated by the heat of steam or boiling water, until a pellicle forms upon the surface, when it is filtered, and set aside to cool ”

“ Consequently, the greater the amount of potassium in our food, the greater will be the loss of sodium chloride from the blood and the tissues, where it is an essential element, with the resultant need of an increased supply in our diet. Where there is an insufficient use of salt, there is a manifest disinclination to partake of the large variety of earth's products rich in potassium. But we are accustomed to the use of far more salt with our food than is necessary; and in excess, it is positively harmful, and the results of its use are serious. ”

“ To destroy the organic matter, the moist method is the one in general use: After reducing the contents of the stomach or the viscus to a pulp, they are mixed with distilled water to the consistency of thin gruel, and placed in a flask with some crystals of potassium chlorate—half an ounce to each pound of the liquid. Pure hydrochloric acid is added, and the flask gently heated on a water bath, a mixture of chlorine and oxides of chlorine is given off and gradually breaks up the organic matter, converting at the same time any mineral poison present into the chloride. ”

“ In solutions containing an excess of potassium cyanide greater than 0.05 molar, the salt K2 [Ag (CN) 3] is formed. The dissociation or instability constant for the complex ion Ag (CN) 32− is 1E−22.
[448] Z. anorg. Chem., 39, 222 (1904) .
[449] The solubility-product constant for silver chloride at 25° is 2E−10. If the concentration of chloride-ion be made 1.0 by the addition of potassium chloride to a 0.05 molar solution of KAg (CN) 2, then the concentration of silver-ion, necessary for the precipitation of the chloride, would be KS.P. / [Cl−] = 2E−10 gram-ion. ”

“ It was first obtained, in an impure condition, in 1828 by A. A. B. Bussy (1794–1882) and F. Wöhler by the reduction of the chloride with potassium, and in 1855 H. J. Debray prepared it, in a compact state, by reducing the volatilized chloride with melted sodium, in an atmosphere of hydrogen. ”

“ Other processes for soda depend upon the electrolysis of sodium chloride solutions. In this case caustic soda and chlorine are the direct products, and the chlorine thus produced and liquefied by pressure in steel cylinders, has become an important commercial article.
In earlier times wood-ashes were the source of potash and potassium salts. Wurtz in the Journal (10, 326, 1850) suggested the availability of New Jersey greensand as a source of potash and showed how this mineral could be decomposed, but it does not appear that this mineral has ever been utilized for the purpose. ”

“ Aniline Black. “Dissolve 20 parts of potassium chlorate, 40 parts of sulphate of copper, 16 parts of chloride of ammonium, and 40 parts of aniline hydrochloride, in 500 parts of water, warming the liquid to about 60°, and then removing it from the water bath. In about three minutes the solution froths up and gives off vapours which strongly attack the breathing organs. If the mass does not become quite black after the lapse of a few hours it is again heated to 60°, and then exposed in an open place for a day or two, and afterwards carefully washed out till no salts are found in the filtrate. ”

“ Mercuric chloride and ammonium chloride, of each 1⁄2 lb.; water, 3 quarts; dissolve, and precipitate with solution of potassium hydrate, q. s.
Prop., &c. A white, inodorous, light mass, or powder; insoluble in alcohol, partially soluble in boiling water, and wholly dissolved by sulphuric, nitric, and hydrochloric acids, without effervescence. It is totally dissipated by heat. When heated with solution of potash, it exhales ammonia, and assumes a yellow colour. Used to make an ointment, which is employed in herpes, porrigo, itch, and other skin diseases, &c. ”

“ The chemical reactions that take place in this couple are multiple. In contact with a sufficiently concentrated solution of hydrate of potassium or sodium, the chloride of silver, especially if it has been recently prepared, passes partially into the state of brown or black oxide, so that the carbon becomes covered, after remaining sufficiently long in the exciting liquid, with a mixture of chloride and oxide of silver. When the circuit is closed, the chloride becomes reduced to a spongy metallic state and adheres to the surface of the carbon. ”

“ It is used in testing for metallic oxides and silica before the blowpipe. The crystals are sometimes used as a standard for phosphoric acid.
"Nessler's Solution."—Mode of preparation: Dissolve 35 grams of potassium iodide in 100 c.c. of water; dissolve 17 grams of mercuric chloride in 300 c.c. of water, and pour this solution into that of the iodide till a permanent precipitate is produced; make up to 1 litre with a 20 per cent. solution of potash; add mercuric chloride till a precipitate is again formed; allow to settle and decant. It is used for detecting ammonia. ”

“ Potassium, when heated, burns in the vapour of carbon bisulphide, forming potassium sulphide and liberating carbon. In contact with chlorine monoxide it forms carbonyl chloride and thionyl chloride (P. Schützenberger, Ber., 1869, 2, p. 219) . When passed with carbon dioxide through a red-hot tube it yields carbon oxysulphide, COS (C. Winkler) , and when passed over sodamide it yields ammonium thiocyanate. A mixture of carbon bisulphide vapour and sulphuretted hydrogen, when passed over heated copper, gives, amongst other products, some methane. ”

“ About 6 parts of the salt are dissolved by 100 of water at 15°, the solubility increasing with the temperature, so that at 100° nearly 60 parts dissolve; if strong sulphuric acid be dropped on the crystals, peroxide of chlorine is evolved; when rubbed with sulphur in a mortar, potassic chlorate detonates. When the salt is heated strongly, it first melts, and then decomposes, yielding oxygen gas, and is transformed into the perchlorate. If the heat is continued, this also is decomposed, and the final result is potassic chloride. ”