Qualities. Form, masses of a foliated, laminar texture, extremely deliquescent; Odour, slight and peculiar; Taste, sharp and pungent. Solubility. f℥j of distilled water at 60° dissolves 404 grains, or 100 parts of it are soluble in 105 parts of water; the solution soon undergoes spontaneous decomposition; it is soluble in four times its weight of alcohol.—Chemical Composition. It consists of one proportional of each of its components, or 48 potass and 50 acetic acid. Incompatible Substances. It is decomposed by tamarinds and most sub-acid fruits; by almost every acid, as well as every variety of neutral salt, whether alkaline, acid, or metallic. Med. Uses. In small doses, diuretic; in larger ones, mildly cathartic. Dose, ℈j to ʒj to produce the former, ʒij to ʒiij to excite the latter of these effects. Forms of Exhibition. On account of its deliquescent property it is not admissible in powders or pills, but should be always exhibited in solution. (Form. 108, 110, 111.) In the former editions of this work, I introduced under the present article, those views regarding the operation of saline bodies upon the kidneys, and their decomposition by the digestive organs, which I considered as capable of throwing some light upon the medicinal operation of these bodies. Having, however, in the present edition of my work devoted a chapter to the consideration of Diuretics, I have necessarily removed all my general observations upon this subject to that part of the work; I therefore entreat the reader to refer to the first part, page 93. Alibert, in speaking of the diuretic virtues of this salt, says that it is so well suited to the sensibility of the Absorbents that its administration is frequently followed by very salutary effects. (Elémens de Thérapeutique, vol. i. p. 327.)
Adulterations. Tartrate of potass is discovered by adding a solution of tartaric acid, which will occasion with it a copious precipitate; the sulphates, by their forming with acetate of lead, or muriate of baryta, precipitates insoluble in acetic or muriatic acid. The brown tinge which it frequently exhibits depends upon the same cause as that which usually imparts colour to the Liquor. Ammon. Acet. This salt is also sometimes contaminated with lead, which arises from its having been prepared by decomposing the acetate of lead by means of carbonate of potass.
POTASSÆ CARBONAS. L.E.
Carbonate of Potass.
Qualities. Form, crystals which are four-sided prisms with dihedral summits, permanent in the air; Taste, slightly alkaline without acrimony. Chemical Composition. It is a bi-carbonate, consisting of two proportionals of carbonic acid and one proportional of potass; and in its crystalline form, it also contains water equal to one proportional. Solubility. It is soluble in 4 parts of cold, and in ⅚ths of its weight of boiling water, in which it is partially decomposed, carbonic acid being emitted during the solution; it is quite insoluble in alcohol. Med. Uses. In cases where an alkali is indicated, this preparation offers an agreeable and efficient remedy; and experience has shewn that its additional proportion of carbonic acid does not in the least invalidate its alkaline agency. In disordered states of the digestive functions, alkalies frequently act with surprising effect; in calculous affections their value has been already noticed (see Liquor Potassæ), and the stomach appears to bear the protracted exhibition of the carbonate of potass or soda, with more temper than it does that of any other alkaline combination; and on account of the increased quantity of carbonic acid which this salt contains, it is preferable for effervescing draughts. (See Acid. Citric. and Form. 123, 168.) Incompatible Substances. Acids and acidulous salts; borax; muriate of ammonia; acetate of ammonia; alum; sulphate of magnesia; lime water; nitrate of silver; ammoniated copper; muriate of iron; sub-muriate and oxy-muriate of mercury; acetate of lead; tartarized antimony; tartarized iron; the sulphates of zinc, copper, iron, &c. Dose, grs. x to ʒss.
POTASSÆ NITRAS. L.E. Nitrum. D.
Nitre or Salt Petre.
Qualities. Form, crystals which are six-sided prisms usually terminated by dihedral summits. Taste, bitter and sharp with a sensation of cold. Chemical Composition. It consists of one proportional of nitric acid, and one proportional of potass. Solubility. It dissolves in seven parts of water at 60°, and in its own weight at 212°. Its solubility is considerably increased by adding muriate of soda to the water; its solution is attended with a great reduction of temperature; it is quite insoluble in alcohol. Incompatible Substances. Alum; sulphate of magnesia; sulphuric acid; the sulphates of zinc, copper, and iron; according to the usual laws of affinity, it should be also decomposed by sulphate of soda; this however only takes place at the temperature of 32°, and then but partially. Med. Uses. Refrigerant, in which case the draught should be swallowed immediately after the solution of the salt is complete, for if it be allowed to stand for some time, its effect with regard to cooling is not nearly so evident (see Form. 138, 144); as a diuretic, its powers are too inconsiderable to be employed, except in combination (Form. 102, 109, 115, 170); a solution of ʒj to f℥vj of rose water forms a good detergent gargle, and a small portion allowed to dissolve slowly in the mouth, will frequently remove an incipient inflammation of the tonsils: for its modus operandi as a diuretic, see Potassæ Acetas. Dose, grs. x to xv, as a diuretic or refrigerant; grs. xxv to xl are aperient, and in large doses it excites vomiting, bloody stools, convulsions, and even death. The best antidotes are opium and aromatics. Impurities. As it occurs from the hand of nature it is far from pure, and even by art it is freed with difficulty from sea salt; the presence and quantity of which in any specimen, may be learnt by adding nitrate of silver to its solution as long as any precipitate is produced.
POTASSÆ SUB-CARBONAS. L.E.
Sub-Carbonas Kali. E.