Potassium iodide

“ But when potassium iodide is exposed to the air, if iodine is liberated, the solution becomes alkaline605 (HO− is formed according to equation (1) ) and the concentration of HO− consequently grows continuously greater. We will, therefore, formulate the problem as follows: how much iodine606 must be liberated, by oxidation of iodide-ion, in molar potassium iodide solution in order to establish equilibrium? For every two molecules of iodine liberated, four HO− ions are formed (equation (1) ) . ”

“ PROCEDURE.—Weigh out on the rough balances 13 grams of commercial iodine. Place it in a mortar with 18 grams of potassium iodide and triturate with small portions of water until all is dissolved. Dilute the solution to 1000 cc. and transfer to a liter bottle and mix thoroughly (Note 1) . [1]
[Footnote 1: It will be found more economical to have a considerable quantity of the solution prepared by a laboratory attendant, and to have all unused solutions returned to the common stock.] ”

“ More recently, iodoform has been prepared by the electrolysis of a solution of potassium iodide in the presence of alcohol or acetone, the electrolytic cell being fitted with a diaphragm, in order to prevent the hydrogen which is formed at the same time from reducing the iodoform, or from combining with the iodine to form hydriodic acid. ”

“ Double Iodide of Silver and Potassium.—I shall feel greatly indebted to you, or to any correspondent of "N. & Q.," for information as to the proportion of iodide of silver to the ounce of water, to be afterwards taken up by a saturated solution of iodide of potassium, and converted into the double iodide of silver and potassium.
I generally pour all waste solution of silver into a jar of iodide of potassium solution; and last year, having washed some of the precipitated iodide of silver, I redissolved it in a solution of iodide of potassium of an unknown strength. ”

“ With the aid of this constant and of equation (2) we can obtain, at least, an approximate interpretation of the results of the exposure of hydroiodic acid and of potassium iodide to the influence of atmospheric oxygen.604 We may [p307] calculate, first, what concentration of free iodine would be required to prevent oxidation of hydroiodic acid, in molar solution, by the oxygen of the air, i.e. to establish equilibrium. ”

“ Mastering the few is said to be the key to success, and the writer believes it, for he has seen it proven. An eminent physician from New York was once called in consultation to a western city. His prescription was mercury iodide, potassium iodide, and infus. gentian. He stated (and the other physician said, “I see”) that the only object of the potassium was to dissolve the mercury iodide. But potassium's great affinity for iodide accepted it, at once dropped the free mercury to the bottom, likely to be taken all at the last dose, equal to fifteen or twenty grains of blue pill. ”

“ Add 25 cc. of iodine solution from a pipette, allowing to drain for a definite time. The excess of iodine should be from 50 per cent to 60 per cent of the amount added, that is, from 100 per cent to 150 per cent of the amount absorbed. Moisten the stopper with a 15 per cent potassium iodide solution to prevent loss of iodine or chlorine but guard against an amount sufficient to run down inside the bottle. Let [Pg 180] the bottle stand in a dark place for 1/2 hr. at a uniform temperature. At the end of that time add 20 cc. of 15 per cent potassium iodide solution and 100 cc. ”

“ These findings were taken to indicate that the iodine-containing fat is absorbed to some extent by the skin. It is generally believed that potassium iodide is not absorbed by the unbroken skin. Therefore it seems reasonable to suppose that the principal iodine effects obtainable from iodine ointment are those due to the free iodine contained in the preparation, supplemented to a slight extent by the iodine which is contained in the fatty ointment base.—Jour. ”

“ It liberates iodine from solutions of potassium iodide, the reaction in neutral solution proceeding thus: O3+2KI+H2O=O2+I2+2KHO, whilst in acid solution the decomposition takes the following course: 4O3+10HI= 5I2+H2O2+4H2O+3O2 (A. Ladenburg, Ber. 1901, 34, p. 1184) . ”

“ A simpler method is to dissolve equal parts of lead nitrate and potassium iodide separately, each in 20 parts of hot water, to mix the solutions and cool quickly, when lead iodide separates in very small crystals. When pure lead iodide is melted in the absence of air, and the fused mass powdered, a product of yet finer colour is formed. It is necessary to completely imbed the crucible in which the fusion is performed in the fire. ”

“ Ammonia neutralizes the free nitric acid. It should be added in slight excess only, since the excess must be removed by boiling, which is tedious. If too much ammonia is present when acetic acid is added, the resulting ammonium acetate is hydrolyzed, and the ammonium hydroxide reacts with the iodine set free.]
[Note 3: A considerable excess of potassium iodide is necessary for the prompt liberation of iodine. While a large excess will do no harm, the cost of this reagent is so great that waste should be avoided.] ”

“ This tendency is overcome by avoiding draughts and regulating the heat; or by placing a lump of magnesite in the flask, which acts by evolving carbonic acid and so producing a steady outward pressure. When the distillation is finished the tube containing the iodine is detached and washed out into a beaker. If the solution is strongly acid it should be almost neutralised by the cautious addition of dilute ammonia. If crystals of iodine have separated, potassium iodide must be added in quantity sufficient to dissolve them. The condenser must be kept cool whilst the chlorine is passing into it. ”

“ Iodine.—Jute absorbs iodine from its solution in potassium iodide. This action is characteristic of all lignified tissues, the quantity of iodine taken up being proportional to the amount of lignification. If the physical conditions remain the same, the amounts of iodine absorbed will be found to be constant for each particular fibre. This constancy points to the formation of a definite chemical compound, probably resembling the blue compound of starch and iodine. This property may be made available for the estimation of the {18} amount of mechanical wood-pulp in papers ”

“ IODUM-MILLER carries a still greater per cent of Iodine in its basic combination....”
According to the label, the preparation is
“An Iodine for External and Internal use ... 45 drops equals 1 dr. by weight. Each drop equals the per cent. of iodine in 1 gr. potas. iodide.”
Iodum-Miller is a heavy, dark liquid having an odor characteristic of ether (ethyl oxid) . Qualitative tests revealed the presence of glycerin, free iodin, iodid and potassium. The specific gravity at 25 degrees was 1.284. Direct titration with sodium thiosulphate solution indicated the presence of 1.68 per cent. ”

“ General Characters.—Iodide of potassium—hydriodate of potash—occurs in cubical crystals of a white or faint yellow colour, very slightly deliquescent when pure, and with a feeble odour of iodine.
Symptoms.—Iodide of potassium acts as an irritant in large doses, producing also many of the symptoms which attend a violent catarrh, with profuse discharge from the nose, lachrymation, and swelling of the eyelids, also pustular eruptions like acne on the face and body generally. Small doses—three to five grains—have produced in some persons most unpleasant and even alarming symptoms. ”

“ Townsend has simplified the process materially, having found that the use of the fluoride and cyanide of potassium, as directed by Le Gray, in no way adds to the efficiency of the process, either in accelerating or otherwise. The iodide and bromide of potassium with free iodine give a paper which produces rapid, sure, and clean results. ”

“ They give with sulphuretted hydrogen a dark brown precipitate, soluble in excess of ammonium sulphide. Potassium iodide gives a brown solution with gradual formation of a precipitate. They form characteristic precipitates with potassium and ammonium chlorides. The platinous salts are brown or colourless solids which, with sulphuretted hydrogen, give a dark brown precipitate of platinum sulphide, and with potassium iodide a gradual precipitation of platinic iodide, PtI2. ”

“ This could hardly be done by a remedy which had only the power of promoting absorption.
It seems that some systems are able to bear with impunity very large doses of Iodide of Potassium. I once met with a medical man who denied its power altogether, because he himself had frequently taken a scruple, and sometimes a drachm at a time, without any effect. Other men are readily affected by very small quantities, and quickly experience the symptoms of Iodism. It is probable that in the former case [Pg 193] the medicine is very quickly eliminated by the kidneys ”

“ Ammonii Iodidum (Ammon. Iod.) , Ammonium Iodide, U.S.P.—NH4I.
White, odorless powder, with a saline taste. Freely soluble in water (1:0.6) , in alcohol (1:3.7) and in glycerin (1:1.5) .
Action and Uses: Those of the iodides. More irritant and less stable than sodium or potassium iodide, over which it has no advantage.
Dosage: 0.3 Gm. or 5 grains (U.S.P.) , in solution.
Linimentum Ammonii Iodidi (Lin. Ammon. Iod.) , Liniment of Ammonium Iodide, N.F.—Ammonium iodide (about 0.5%) with oil of rosemary, oil of lavender, camphor, ammonia water and alcohol. ”

“ The acid distillate containing the arsenious chloride may be left for an hour or so without much fear of oxidation; but it is safer to neutralise and then to add the bicarbonate of soda, as the following experiments show. Several portions of a solution, each having a bulk of 100 c.c., were exposed for varying lengths of time, and the arsenic in each determined.
The Titration.—Make a standard solution of iodine by weighing up in a beaker 16.933 grams of iodine and 30 grams of potassium iodide in crystals; add a few c.c. of water, and, when dissolved, dilute to 1 litre: 100 c.c. ”

“ Tinctura Iodi Decolorata (Tr. Iod. Decolor.) , Decolorized Tincture of Iodine, N.F.—A solution of sodium iodide [Pg 119] and ammonium iodide obtained by mixing iodine and sodium thiosulphate (each 8.3%) , stronger ammonia water (6.5%) and alcohol. Absolute alcohol content about 75 per cent. Does not contain free iodine.
Uses: For external use; of doubtful utility.
Tinctura Iodi Fortior (Tr. Iod. Fort.) , Stronger Tincture of Iodine, N.F. (Churchill’s Tincture of Iodine) .—Iodine (16.5%) and potassium iodide (3.3%) in water and alcohol. Absolute alcohol content about 65 per cent. ”

“ 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. ”

“ The tests and actions of this poison have been examined by M. Devergie; and more lately its medico-legal chemistry has been investigated by Dr. O’Shaughnessey and Professor Orfila.
It is sold in the shops of various degrees of purity. Pure iodide of potassium is in white crystals, tending to the cubical form, permanent in the air, possessing a faint peculiar odour, and easily soluble in both water and rectified spirit. Another variety has the same form, but possesses an odour of iodine, is often yellowish in colour, and deliquesces slightly in moist air. ”

“ In medicine iodine is frequently applied externally as a counter-irritant, having powerful antiseptic properties. In the form of certain salts iodine is very widely used, for internal administration in medicine and in the treatment of many conditions usually classed as surgical, such as the bone manifestations of tertiary syphilis. The most commonly used salt is the iodide of potassium; the iodides of sodium and ammonium are almost as frequently employed, and those of calcium and strontium are in occasional use. ”

“ I can hardly imagine that the increased sensitiveness mentioned by Mr. Hennah is really due to the free iodine which he introduces. Such a result being so contrary to all my experience, I would venture to suggest that there must be some other cause for its beneficial action; for instance, commercial iodide of potassium is generally alkaline, owing to impurities present; the tincture of iodine in this case would render the collodion neutral, and unless a very large excess of iodine were introduced, its good effects would be very apparent. ”

“ 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. ”

“ Iodide of potassium gives the same when the iodine is set free by an acid, such as sulphuric acid.
2. It also forms a scarlet precipitate with perchloride of mercury; and
3. It gives a yellow precipitate with acetate of lead.
CHAPTER XIV. PHOSPHORUS. This substance is sold in a pure state in small wax-like cylinders, which must be preserved under [Pg 64] water. It is soluble in oil, alcohol, ether, and chloroform, and still more so in carbon disulphide; it is luminous in the dark, and it ignites at a very low temperature, giving off a dense white smoke. ”