Note 645 — PHARMACOLOGIA. (continued 7)

Cheltenham Salts.—A factitious compound has been long vended, as a popular purgative, under this name; it is formed by triturating together the following salts. Sulphate of Soda, grs. 120. Sulphate of Magnesia, grs. 66. Muriate of Soda, 10. Sulphate of Iron, gr. ½. As a purgative it is very efficacious, and superior probably to that which is actually obtained by the evaporation of the Cheltenham water itself; for notwithstanding the high pretensions with which this latter salt has been publicly announced, it will be found to be little else than common Glauber’s Salt. This fact has been confirmed by the experiments of Mr. Richard Phillips, (Annals of Philosophy, No. lxi,) who observes, that the “real Cheltenham Salts contain no chalybeate property, but are merely sulphate of soda, mixed with a minute quantity of soda, and a very small portion of common salt.” It could not be imagined that the salt should contain oxide of iron even in a state of mixture, much less in combination, for carbonate of iron is readily decomposed by ebullition, and the oxide of iron is precipitated before the salt can be crystallized. A preparation, under the name of Thomson’s Cheltenham Salts, is accordingly manufactured in London, by evaporating a solution consisting of sulphate of soda and sub-carbonate of soda.

“Efflorescence of real Cheltenham Salts.” The preceding salt deprived of its water of crystallization.

“Efflorescence of real Magnesian Cheltenham Salts,” made from the Waters of the Chalybeate Magnesian Spa. This is asserted to be a sub-sulphate from nature, which combines both a pure and a sub-sulphated magnesia in its composition; “but,” says Mr. Phillips, “neither nature nor art has ever produced such a combination; in truth, it consists of Epsom Salt, with small portions of magnesia, and muriate of magnesia or muriate of soda.”

Murio-sulphate of Magnesia and Iron. The preparation thus named by Mr. Thomson, was found by Mr. Phillips to consist of Epsom Salt, deprived of part of its water of crystallization, and discoloured by a little rust of iron, and containing a small portion of muriate of magnesia.

Thus it appears, that not one of these preparations is similar to the water which is drank at the Spa; in order to remedy this difficulty, Mr. Thomson prepared the “Original Combined Cheltenham Salts,” by evaporating the waters to dryness: but a very small share of chemical penetration is required to satisfy us that no process of this description can remedy the defect described, for as Mr. Phillips has observed, the chalybeate properties of the water must be essentially altered by such an operation.