1818.] An Analysis of the Cheltenham Salts. 2§ 



produce the slightest indication of the presence of oxide of 

 iron, although it is capable of detecting less than the 10000th 

 part of a grain of the oxide. 



The result of this experiment was not unexpected ; for it 

 could scarcely be supposed that the salt should contain oxide of 

 iron even in a state of mixture, and much less in that of combi- 

 nation ; for carbonate of iron is readily decomposed by ebulli- 

 tion, and the oxide of iron is precipitated, before the salt can 

 be crystallized. 



I next examined whether this Glauber's salt is mixed with 

 common salt, as is usually the case. To 100 grains dissolved in 

 distilled water some nitric acid was added, and afterwards solu- 

 tion of nitrate of silver, until no further precipitation ensued ; the 

 precipitated horn silver weighed, after fusion, three grains, indi- 

 cating about T3 gr. of common salt; whereas an equal portion 

 of the common Glauber's salt of the shops, when similarly 

 treated, yielded such a quantity of precipitate as showed that it 

 contained only -p -th part as much common salt. 



From these statements, it is evident that the " real Chelten- 

 ham salts " contain no " chalybeate property ; " that they are 

 merely sulphate of soda, or Glauber's salt, mixed with a minute 

 quantity of carbonate of soda, productive of no good effect, and 

 a small portion of common salt, incapable of a bad one. 



The next saline preparation is described by Mr. Thompson as 

 the " efflorescence of real alkaline Cheltenham salts," &c. Of 

 this it is requisite merely to state, that it is the preceding 

 Glauber's salt deprived of its water of crystallization ; and that 

 it contains no chalybeate property whatever, as asserted by the 

 proprietor. 



Among other merits which Mr. Thompson ascribes to the 

 salts I have just noticed is this, that " the aperient and tonic 

 qualities are nicely proportioned by nature." Now if by "tonic 

 qualities " be meant " chalybeate nature," I have shown that 

 they are totally destitute of it ; and if it be meant that the sul- 



Shate of soda resembles what is usually produced, no one will 

 isturb its claim to the distinction : but with the next described 

 compound the case is different ; and although it is asserted to 

 be from nature, neither nature nor art has ever produced it. This 

 salt is termed by Mr. Thompson the " efflorescence of real mag- 

 nesian Cheltenham salts made from the waters of the Chalybeate 

 Magnesian Spa ; " and it is asserted to be " a subsulphate from 

 nature which combines both a pure and a subsulphated magnesia 

 in its composition." 



Although this salt must be deprived of the encomium be- 

 stowed upon it, yet supposing that it might possess some claim 

 to attention, it was submitted to examination. 



Five hundred grains of this preparation were put into distilled 

 water, and boiled ; the whole was dissolved, excepting 0'3 of a 

 grain ; this insoluble portion was white, and probably magnesia, 



