SALT, one of the great divisions of natural bodies. The characteristic marks of salt have usually been reckoned its power of affecting the organs of taste, and of being soluble in water. But this will not distinguish salt from quicklime, which also affects the sense of taste, and dissolves in water; yet quicklime has been universally reckoned an earth, and not a salt. The only distinguishing property of salts, therefore, is their crystallization in water: but this does not belong to all salts; for the nitrous and marine acids, though allowed on all hands to be salts, are yet incapable of crystallization, at least.
least by any method hitherto known. Several of the imperfect neutral salts also, such as combinations of the nitrous, muriatic, and vegetable acids, with some kinds of earths, crystallize with very great difficulty. However, by the addition of spirit of wine, or some other substance which absorb part of the water, keeping the liquor in a warm place, &c. all of them may be reduced to crystals of one kind or other. Salt, therefore, may be defined a substance affecting the organs of taste, soluble in water, and capable of crystallization, either by itself or in conjunction with some other body; and, universally, every salt capable of being reduced into a solid form, is also capable of crystallization per se. Thus the class of saline bodies will be sufficiently distinguished from all others; for quicklime, though soluble in water, cannot be crystallized without addition either of fixed air or some other acid; yet it is most commonly found in a solid state. The precious stones, basaltics, &c. though supposed to be formed by crystallization, are nevertheless distinguished from salts by their insipidity and insolubility in water.
But acids and alkalis, and combinations of both, when in a concrete form, are salts, and of the purest form. Hence we conclude, that the bodies, to which the name of salts more properly belongs, are the concretions of those substances; which are accordingly called acid salts, alkaline salts, and neutral salts. These last are combinations of acid and alkaline salts, in such proportion as to render the compounds neither sour nor alkaline to the taste. This proportionate combination is called saturation: thus common kitchen salt is a neutral salt, composed of muriatic acid and soda combined together to the point of saturation. The appellation of neutral salts is also extended to denote all those combinations of acids, and any other substance with which they can unite, so as to lose, wholly or in great measure, their acid properties.
But although this general definition of salts is commonly received, yet there are many writers, especially mineralogists, who confine the denomination of salts in the manner we first mentioned, viz. to those substances only which, besides the general properties of salts, have the power of crystallizing, that is, of arranging their particles so as to form regular shaped bodies, called crystals, when the water superfluous to their concrete existence has been evaporated.