130 Artificial Preparation of Medicinal Waters. 
collect the residuum to be dissolved in common water, and to be used 
* medicinally ; but whatever foundation there may be for such a prac- 
ice in the case of the simple saline spring at Epsom, and others, 
nothing can be more improper than pursuing it with the Congress 
water, the residuum of which, after evaporation, consists of various 
substances, some of which are perfectly inert after the carbonic acid 
has been expelled ; thus composing a mixture partly insoluble, and 
not only nauseous to a degree, but actually not free from qualities 
which are injurious to the system when taken in any quantity. 
Since the properties of carbonic acid gas have been investigated 
by Black, Priestley, and other chemists, much light has been thrown 
upon the most important phenomena in nature, but on none more than 
in explaining the nature and properties of mineral waters. It has been 
shown to be the principal agent in their production as well as in pro- 
moting the solution of several substances which are otherwise insolu- 
ble in pure water. It is this gas which holds the iron and earths in 
solution ; it is this which gives the agreeable pungent taste to the water, 
and it is also this gas which produces that exhiliration of spirits which 
almost all persons feel after drinking such waters. As soon as it was 
ascertained that water could be impregnated with this gas, and that 
it then resembled, in every respect, the waters of Spa, Seltzer, and 
wong it was immediately proposed to make use of it to imitate 
e taste and medicinal qualities of those natural springs. Bergman 
accordingly took advantage of this discovery, and although at that 
time the process of impregnating water with carbonic gas was not as 
well understood as it is at present, yet he succeeded in imitating ef- 
fectually all those mineral waters with which he was at that time ac- 
quainted, and thus rendered to his countrymen a most important ser- 
vice. The apparatus for conducting the process of impregnating 
water with gas has been, since that period, so improved, that by an 
instrument adapted to the purpose, carbonic acid gas has been forced 
into water, to the quantity of three times its bulk, much more than 
any water can take up by the common process of nature. 
© experience of many years has not lessened the confidence of 
the public in the use of these artificial mineral waters, it having been 
found that their medicinal qualities are equal to those of the natural 
spring, and that in many instances they may be rendered superior, 
by adding, if necessary, a larger quantity of the most useful sub- 
stances or by omitting others which are either unnecessary or injuri- 
ous to health. 
