Potassium bitartrate

“ Bitartrate of potassium, 2 lbs., is exposed to a red heat in an iron crucible, as before; the powdered calcined mass is boiled for 20 minutes in water, 1 quart, the solution filtered, and the filtrate washed with water, 1 pint, to which ammonium sesquicarbonate, 1⁄2 oz., has been added; the mixed and filtered liquors are evaporated to dryness, and, a low red heat having been applied, the residuum is rapidly reduced to powder in a warm mortar, and at once enclosed in (dry and) well-stoppered bottles. ”

“ As a medicine it acts as a gentle diuretic and aperient, and is valued for correcting the griping properties of senna and resinous purgatives. It is also antiscorbutic.—Dose, 1⁄2 dr. to 3⁄4 oz., in powder, or dissolved in water. The solution changes the colour neither of litmus nor turmeric. The addition of almost any acid throws down crystals of bitartrate of potassium, which generally adhere to the vessel. The precipitate occasioned by either chloride of barium or acetate of lead is dissolved by dilute nitric acid. ”

“ Unfortunately, bichromate of potash is not very soluble in water; one pint of water will not take up much more than three [Pg 47] ounces of this salt. Hence, though the solution of potassium bichromate is an excellent depolariser as long as it contains any of the salt, it soon becomes exhausted. When bichromate of potash is used in a cell along with sulphuric acid and water, sulphate of potash and chromic acid are formed, thus:—
From this we learn that before the potassium bichromate enters into action in the battery, it is resolved into chromic acid. ”

“ 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. ”

“ Heat gently for a few minutes, and then boil until the nitric oxide is expelled. An atmosphere of carbon dioxide must be kept up. Dilute with water, and titrate the residual iron with standard solution of bichromate of potassium. The standard "bichromate" is made by dissolving 17.5 grams of the salt (K2Cr2O7) in water, and diluting to 1 litre: 100 c.c. equal 2 grams of iron. Deduct the weight of iron found from the 2 grams originally taken, and multiply by 0.3214. This gives the weight of the pentoxide in the sample. In an example, 0.5 gram of nitre was taken, and 59.4 c.c. ”

“ When the potash is saturated, the operation is completed. The Germans recommend a strong, alcoholic solution of potassa to be used in the second vessel, for in this case, the hydrocyanic or prussic acid combines with the potassa, forming a hydrocyanate of potassa, or, the water being abstracted, the cyanuret of potassium, which spontaneously precipitates, on the saturation of the fluid, the cyanuret, being insoluble in strong alcohol. The ferrocyanate of potash may be considered as containing three equivalents of hydrocyanic acid, two of potash and one of iron ”

“ The picrate of potassium has been given with advantage in intermittent fevers. A solution of picric acid in alcohol is an excellent test for potassa, if there be not too much water present, as it throws down a yellow crystalline precipitate with that alkali, but forms a very soluble salt with soda. Most of the picrates may be made by the direct solution of the carbonate, hydrate, or oxide of the metal, in a solution of the acid in hot water. The picrate of silver forms beautiful starry groups of acicular crystals, having the colour and lustre of gold. ”

“ It is used as a test and for dissolving iodine. It should be used in a 10 per cent. solution freshly made. The solution decomposes on exposure to light, with separation of iodine.
Potassium Nitrate (KNO3) can be purchased pure. It is used in the dry way as an oxidizing agent. It is very fusible. It decomposes at a low temperature into potassium nitrite (KNO2) and free oxygen; and at a higher temperature leaves potash (K2O) . It oxidizes sulphur and carbon with explosive violence. This action may be moderated by mixing the nitre with carbonate of soda, common salt, or some other inert body. ”

“ In 1807, Sir Humphry Davy discovered the metal potassium by subjecting moistened potash to the action of a powerful voltaic battery; the positive pole gave off oxygen and the metallic globules of pure potassium appeared at the negative pole. It is never found uncombined in nature. Now if potassium is heated in cyanogen gas (a gas procured by heating mercury) or obtained on a large scale by the decomposition of yellow prussiate of potash, a white crystalline body very soluble in water, and exceedingly poisonous, is obtained. ”

“ It is generally known as the “Forchammer” or “oxygen” process, and, although of undoubted service in comparing the quality of samples of very impure water, it is defective in the following important respects: Different organic substances are not affected to an equal extent by potassium permanganate; albumen, for instance, being far less easily oxidised than other compounds, and the value of the results afforded is vitiated by the presence of certain inorganic bodies, such as nitrites, sulphuretted hydrogen, ferrous salts, etc. ”

“ To render the product absolutely pure, it is redistilled in an iron or green-glass retort, into which some naphtha has been put, that its vapour may expel the air, and prevent the oxidation of the metal. The pieces of charcoal are introduced for the purpose of absorbing the melted carbonate of potassium and preventing its separation from the finely divided carbonaceous matter. Prod. 3% to 4% of the weight of tartar acted on; 1 lb. yielded 280 gr.
Prop., &c. Pure potassium is a brilliant white metal, with a high lustre ”

“ Hence tart wines, which owe their acidity to too great a proportion of tartaric acid or bitartrate of potass, cannot be improved by adulteration with oxide of lead. For the bitartrate of potass cannot act at all as a solvent on the oxides or carbonate of lead, and even pure tartaric acid takes up so little, that wine containing it, could not acquire the sweet taste which is the purpose of the adulteration. ”

“ Diamond through your valuable publication, that I am, in common with many others, extremely indebted to him for his collodion, and would esteem it a favour if he would answer the following Queries, viz.:
1st. He says, in answer to a previous Query, that "nitrate of potassa" is not formed in his process. Now I wish to ask if (as the iodide of silver is redissolved in iodide of potassium) it is not formed when the plate is plunged into the nitrate silver bath, as the nitrate decomposes the iodide of potassium? ”

“ The paper will be found covered with a solution of ordinary potash. If turmeric paper be used, the course of the potassium will be marked with a deep brown color.—Corollary. Hence, if you touch potassium with wet fingers you will burn them.
If a small piece of the metal be placed on a piece of ice, it will instantly take fire, and form a deep hole, which will be found to contain a solution of potash.
In consequence of its great affinity for oxygen, potassium must be kept in some fluid destitute of that element, such as naphtha. ”

“ One feels unwilling to admit of a tritoxide, (and that perhaps the only one existing,) when the deutoxide is unknown, were it not upon good authority. The obscurity on this subject may be removed by future experiments.
It may be proper to add that Gay Lussac and Thenard concur with Davy in assigning a much greater saturating power to potassium and sodium than to the fused hydrates of potash and soda of equal weights. From the table, Recherches, Tom. 2, p. 214, it may be deduced that 35 potassium [Pg 56] require as much sulphuric acid to saturate them as 50 or more of the hydrate of potash ”

“ Koettstorfer’s method [28] is based upon the fact that, as butter fat contains the fatty acids, having a smaller molecular weight than those present in other fats, it must contain more molecules of acid, and will therefore require a greater amount of an alkali to effect saponication. The process is executed as follows:—One or two grammes of the filtered fat are weighed out in a narrow beaker and heated over a water-bath with about 25 c.c. of one-half normal alcoholic solution of potassium hydroxide. The saponification of the fat is assisted by repeated stirring ”

“ Two drops of a 10 per cent. solution of potassium iodide are next added to the flasks, and the amount of iodine liberated (which is equivalent to the quantity of permanganate unacted upon [205] by the water) is determined by titration with the sodium hyposulphite solution. The precise end of the reaction is ascertained by means of a few drops of the starch paste, the hyposulphite being added to each flask until the blue colour produced by the starch disappears. The quantities of solution used in each titration are then read off. ”

“ It forms a grey brittle mass, having a conchoidal fracture; it is Very deliquescent, combining very energetically with water to form caustic potash. According to Holt and Sims (Journ. Chem. Soc., 1894, p. 438) , the substance as obtained above always contains free potassium. Potassium hydroxide or caustic potash, KOH, formerly considered to be an oxide but shown subsequently to be a hydroxide of potassium, may be obtained by dissolving the metal or monoxide in water, but is manufactured by double decomposition from potassium carbonate and slaked lime: K2CO3+Ca (OH) 2=2KOH+CaCO3. ”

“ Bi, 81·25 per cent., S, 18·75 per cent., occurs, in the course of analysis, as a brownish-black or quite black precipitate, insoluble in water, dilute acids, alkalies, alkaline sulphides, sulphate of soda, and cyanide of potassium, but dissolving in moderately concentrated nitric acid with separation of sulphur. It continually increases in weight when dried in the ordinary way, and is completely reduced when fused with cyanide of potassium. ”

“ Standard solutions should not be kept in a place exposed to direct sunlight. Oxidising and reducing solutions, such as those of permanganate of potash, ferrous sulphate, iodine, hyposulphite of soda, &c., gradually weaken in strength; the solutions of other salts are more stable; while those of potassium bichromate and baric chloride are almost permanent. Solutions of potassium permanganate may be kept for a month or so without much change. The solutions of hyposulphite of soda and of iodine should be examined weekly. ”

“ A very good test is the process of reduction with potass, by which globules of mercury are sublimed, and a chloride of potassium left in the flux, as may be proved by the action of nitrate of silver on the solution of the flux previously neutralized with nitric acid. ”

“ Bismuth.—The nitrate or magistery of bismuth has caused death in nine days, after a dose of two drachms. The symptoms were those of a strong irritant, but in all probability were caused by some impurity in the substance. Arsenic is frequently present in this way. As no antidote is known, vomiting must be promoted and emollient drinks freely given.
Chrome.—The bichromate of potassium is found in the form of orange-red crystals, which yield a yellow acid solution. It is used as a dye, and has caused death in more than one instance. Emetics and magnesia or chalk, must be the remedies employed. ”

“ Hard soap is a combination of oil or fat, and soda. The quantity of real alkali in potash may be known by the proportion of acid required to saturate a given weight of it. Potash, pearl-ash, salt of tartar, and salt of wormwood are all carbonates of potassa. This alkali is called the vegetable alkali, because it is obtained from vegetables. It is considered to be the hydrated deutoxide of potassium, and when decomposed will furnish potassium.
Table of the saline or soluble products of one thousand pounds of ashes of the following vegetables. ”

“ That cannot, however, be precisely the reason, for when potassium is introduced under water, without contact of air, the combustion is not so rapid, and indeed, in that case, there is no luminous appearance; but a violent action takes place, much heat is excited, the potash is regenerated, and hydrogen gas is evolved.
Potassium is so eminently combustible, that instead of requiring, like other metals, an elevation of temperature, it will burn rapidly in contact with water, even below the freezing point. ”

“ The salt of commerce is frequently contaminated with large quantities of sulphate or chlorate of potassium. To detect these, M. Zueber adds tartaric acid, dissolved in 50 parts of water, to a like solution of the sample. As soon as the decomposition is complete, and the colour verges towards the green, the supernatant liquor should afford no precipitate with solutions of the nitrates of silver and barium, whence the absence of chlorides and sulphates may be respectively inferred. ”

“ Plates should always be kept in a dry room. The dark room is seldom a safe place for storage, because it is apt to be damp.
Various developing agents give different results. Pyrogallic acid in combination with carbonate of sodium or carbonate of potassium gives strong, vigorous negatives. Eikonogen and metol yield soft, delicate negatives. Hydrochinon added to eikonogen or metol produces more contrast or greater strength.
It is essential to have a bottle of bromide of potassium solution, 10 per cent, in the dark room. (One ounce of bromide of potassium, water to 10 ounces.) ”