Art. XVI. Analysis of the Harrodsburg Salts.
Art. XVI. Analysis of the Harrodsburg Salts, by Edward D. Smith, M. D. Professor of Chemistry and Mineralogy in the South-Carolina College.
More than a year since I received a quantity of a white earthy substance, which was said to be obtained by the evaporation of certain mineral waters at Harrodsburg, Kentucky, and there vended at a considerable price, under the name of Epsom salts. The respectable character who presented this powder to me, requested that I would make an analysis of it; but I had not sufficient leisure until lately, to pay the requisite attention to this subject. The results of my examinations are now submitted to the public eye.
The external qualities of this substance are as follow: small white lumps, hard to the touch, but dry and easily yielding to pressure, somewhat gritty to the teeth, and imparting an earthy and saline taste to the tongue.
1. 120 grains of the powder were put into about a half ounce of alcohol, digested for six hours, then, washed with more alcohol, filtered and carefully dried.
2. On weighing the dry powder, the loss appeared to be but one grain, so that it contains very little of any substance which is soluble in alcohol.
3. 115 grains (four grains having been lost in the transfer from the filter) were collected and put into rather more than eight times their weight of cold distilled water, and digested for two hours.
4. This watery solution was then filtered, and on weighing, the residue appeared to be 48 grains, so that 67 grains must have been dissolved.
5. 10 grains of the insoluble residue (4) were put into a flask, with 10 ounces of distilled water, and boiled for 1 hour.
6. A small portion of this solution, on being tested with nitrate of barytes, gave a copious white precipitate, with oxalic acid, a white cloud; with ammonia, a slight white cloud; with muriatic acid, a slight bluish tinge. From these tests it was inferred that sulphate of lime was present, with perhaps a slight trace of muriate of lime.
7. The remainder of this solution was filtered, and on weighing the dried residuum, the loss appeared to be 2 grains, so that sulphate of lime probably constitutes nearly ⅕ of the insoluble residence (48 grains. 4.)
8. The watery solution, (4) which was supposed to contain 67 grains, was evaporated, and left a residue that weighed but 34 grains, so that 33 grains must have disappeared in the process.
9. Some of this residue dissolved in distilled water, was tested with carbonate of soda, forming an immediate white cloud; with nitrate of barytes, the same; with ammonia, the same; but with oxalate of ammonia, it did not form any cloud until it had stood some time, and then it was slight. From these tests it was inferred that sulphate of magnesia was present.
10. A portion of the dried residuum (7) was treated with diluted muriatic acid, which dissolved nearly the whole of it, with considerable effervescence. The new compound, on examination, proved to be muriate of lime; so that it may be concluded the residuum (7) was principally carbonate of lime.
On considering the results of the preceding experiments, it will appear that more than one half of the substances submitted to analysis, was easily soluble in water, and from the chemical tests used, that it was composed principally of sulphate of magnesia, (Epsom salt) with perhaps a small portion of muriate of lime or magnesia, that of the remainder, about ⅕ was sulphate of lime, and difficultly soluble in water; and that the rest was perfectly insoluble in water, and consisted principally of carbonate of lime.
There can be no doubt then, that the Harrodsburg salt, in its present state, is very improperly prepared, containing in its composition a large proportion of matter, that is not only inert, but which may produce considerable inconvenience and injury in the stomach and bowels, from its ponderous nature and tendency to form mechanical obstructions. Perhaps the occurrence of such injury may not be frequent, from the circumstance of a large portion of the salt being so insoluble; but admitting this to be the fact, there is a manifest impropriety in offering to the public, as medicine, an article which cannot be used as such. Probably the proprietors of this manufactory are not aware of the real nature of the case, and of the facility with which, by a little additional trouble, they could separate the useful and valuable material, from that which is at least useless, and which might also be pernicious.
South-Carolina College, March, 1819.