1. In the case of the Sulphates.

That water may act the part of a base in the constitution of certain hydrates of salts and of acids, had been established by the author in the case of the phosphates. The peculiarity of phosphoric acid is its capacity to unite with water as a base in several proportions, while all other acids combine with water as a base in one proportion only, so far as is yet known. By the author's discoveries in regard to phosphoric acid, the ordinary conceptions entertained of the constitution of salts were completely deranged. The salts called biphosphate of soda, phosphate of soda, and subphosphate of soda, were proved to be all tribasic salts. The common idea of a super-salt is inapplicable to any of them.