Preparation and Properties. This salt is prepared by saturating a solution of citric acid with bicarbonate of potassa, and evaporating to dryness. The bicarbonate of potassa is preferred to the carbonate, because it is purer, as the latter is generally procured. The carbonate, however, is used in the British process. The salt is susceptible of crystallization, but is usually prepared in the amorphous state. As kept in the shops, it is in the form of a white granular powder, inodorous, of a peculiar, saline, not unpleasant taste, deliquescent, very soluble in water, and insoluble in alcohol. it is decomposed at a red heat, leaving a residue of carbonate of potassa. it is known to contain no tartrate, by not yielding a precipitate of bitartrate of potassa, on the addition of muriatic acid.

Medical Effects and Uses

in the ordinary state of the circulation, this salt cannot be depended on for diaphoretic operation; but, when the skin is hot and dry, and the circulation accelerated, there is no diaphoretic which operates more certainly and effectually. it appears to reduce the irritation of the surface to a point at which secretion can take place, while it directly stimulates the secretory function of the sudoriferous glands; and, as the vessels are full of blood, and the current rapid, we have the conditions most favourable to copious diaphoresis.

Either simply dissolved in water, or in the forms of the neutral mixture and effervescing draught, to be described immediately, it is admirably adapted to all cases of inflammatory and febrile disease, in which the skin is hot and dry. it is less powerfully depressing to the circulation than tartar emetic, and, therefore, not so effectual as an antiphlogistic remedy; but it is, I think, more certain as a mere diaphoretic. in the paroxysm of our miasmatic fevers, in the febrile stage of yellow fever, in all the exanthemata, and all the phlegmasiae, it may be used advantageously, under the circumstances mentioned. in the first week or two of typhoid fever, and, indeed, throughout both that fever and the typhus, whenever the skin is hot and dry, it may be given with advantage, and without the fear of depression, such as, in the same condition, might be apprehended from the antimonials. Another great recommendation is its general acceptability to the palate and stomach. The probability is that this salt operates as a depressing agent, partly by more highly alkalizing the blood; as the alkaline salts with vegetable acids undergo a change in the system, by which the acid is digested, and the alkali is left in the blood, to be thrown off by the kidneys. Hence this, with other similar salts, are indicated whenever it is desirable to render either the blood or the urine alkaline.

Administration

The dose of citrate of potassa is from twenty to thirty grains, to be repeated every hour, two, or three hours, according to the violence of the fever. it should be given dissolved in from one to two fluidounces of water; but I much prefer it in one of the modes of extemporaneous preparation mentioned below.