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18 a liquid state, be mixed together, they will immediately unite; and, provided the alkali has not been deprived of its fixed air, their union will be attended with a very considerable effervescence, or seeming fermentation.

If the alkali has been deprived of air, no effervescence will ensue, but they will quietly mix together; but, if a due proportion of each has been added, the liquor will neither have the properties of an acid nor an alkali, but will be what is called neutral. The bringing the liquor into this state is called saturating the acid, or alkali, or, combining them to the point of saturation.

If the liquor, after such a saturation, be gently evaporated, a saline mass will be left, which is neither an acid nor an alkali, but a new compound, formed by the union of the two, and which is called a perfect neutral salt. The epithet perfect is given it,