Artificial Preparation of Medicinal Waters. 129 
In order to obtain those substances on which the medicinal quali- 
ties of the Cheltenham water principally depend, the salts are pro- 
cured on the spot by evaporation and crystallization, and sold ata 
high price, under the name of Cheltenham salts; but as these can 
be nothing more than a mixture of sulphate of soda and sulphate of 
magnesia, in the above proportions, it is evident that salts possessing 
the same qualities, when dissolved in common water, can be artifi- 
cially prepared, and sold for the same purpose, at a comparatively 
trifling expense. Thus are the ignorant imposed upon, from not 
knowing that neutral salts, of the same species, possess the same 
qualities, from whatever water they are produced. Although these 
salts are the chief ingredients in Cheltenham water, they cannot be 
said to be the only ones, and in order to imitate exactly the natural 
water, recourse must be had to the usual method of impregnating 
water with carbonic acid gas, and supplying a small quantity of iron, 
in addition to the salts—ingredients much relied on at Cheltenham, 
but which in fact, as I have ascertained myself on the spot, are found 
in it in such small quantities as to be scarcely noticed or to add much 
to the medicinal qualities of the water. 
_ The practice of substituting artificial crystallized salts for those ob- 
tained from the natural springs at Cheltenham, was so successful, that 
a similar attempt was made to impose on the ignorant, by collecting 
the residuum obtained by evaporation from the waters of Harrowgate, 
and even to imitate this residuum, and recommend it, when dis- 
solved in water, as a substitute for the water at the spring; this, howev- 
er, did not, nor could it, indeed, continue long to impose on the public. 
When the real causes of the properties of Harrowgate waters were dis- 
covered, it was ascertained that they resided in other substances than 
the mere neutral salts, and that these substances could not be obtained 
by evaporation, but on the contrary were dissipated by the process. 
These substances were carbonic acid gas and sulphuretted hydrogen 
gas, imparting peculiar properties to the water and assisting in the 
solution of others. When the water was evaporated, the residuum 
of course, possessed none of its most valuable properties, but when 
dissolved in common water, became a most nauseous, and somewhat 
inert draught, possessing no longer any medicinal effect, except 
what it derived from the neutral salt which was deposited by close 
evaporation. ‘The same mistaken view of this matter subsisted for 
a length of time in this country, and is still carried into practice at 
Saratoga, by evaporating the water of the Congress spring, and they 
Vou. XXII.—No. 1. 17 
