28 An Analysis of the Cheltenham Salts. [Jan. 



Article V. 



An Analysis of the Salts prepared by Mr. Henry Thompson from 

 the Cheltenham Waters. By Richard Phillips, F.L.S. and 

 M. Geol. Soc. 



The various saline compounds procured from the waters of 

 Cheltenham are introduced to public notice with such high pre- 

 tensions to peculiar and superior qualities, that the investigation 

 of their nature cannot fail to be useful ; for if it should be 

 proved that the encomiums bestowed by Mr. Thompson upon 

 the excellence of his preparations are justly merited, it must be 

 advantageous to be enabled to imitate, when it may be impos- 

 sible to procure them. 



In order to effect this examination, I procmed some of the 

 salt which is described as " crystals of real Cheltenham salts, 

 made from the waters of Mr. Henry Thompson's Montpelier Spa 

 at Cheltenham." These salts are asserted " to contain all the 

 native chalybeate and other properties for which the waters at 

 Cheltenham are so universally esteemed," &c. Sec. To this Mr. 

 Thompson adds, that " it is the opinion of physicians that 

 neither the alkaline foundation [base], nor the chalybeate nature 

 in Mr. Thompson's Cheltenham's salts, can be equalled by those 

 artificial compounds in the spurious Cheltenham salts that are 

 made in imitation of them." The crystalline form of this salt is 

 sufficient to convince any one who has the slightest knowledge 

 of the subject, that it is chiefly sulphate of soda, or common 

 Glauber's salt. 



It is, however, well known that some salts during crystalliza- 

 tion take up other substances which are foreign to their nature, 

 without producing any remarkable alteration in their appearance. 



In order to ascertain whether any such event had occurred to 

 this salt, and especially whether it contained carbonate of soda, 

 of which the waters hold a small quantity in solution, I dissolved 

 120 grains in distilled water; and having put apiece of turmeric 

 paper into the solution, I found that after some time it was dis- 

 tinctly reddened, indicating the presence of an alkali. 



To determine the quantity of the carbonate of soda, I added 

 to the solution dilute sulphuric acid of known strength, and I 

 found that when .J-th of a grain of sulphuric acid had been used 

 litmus paper was reddened by the solution : therefore a quarter 

 of an ounce of the salt in question, which is the quantity men- 

 tioned by Mr. Thompson as a dose, contains scarcely ^th of a 

 grain of dry carbonate of soda. 



I then dissolved another portion of the salt, to try whether, as 

 is asserted by Mr. Thompson, it contains any chalybeate im- 

 pregnation : but the addition of tincture of galls did nol, 



