Water is an uninflammable fluid, says Dr. O. Gregory, and, when pure, is transparent, colorless, and void of taste and smell. Mr. Cavendish made a discovery that it is formed by the union of _hydrogen_ and _oxygen_. It may, therefore, be considered as _oxide of hydrogen_: oxygen and hydrogen appearing to unite, only in that certain proportion of which water is the result. In 1798, (observes Mr. Parkes) Mr. Sequin made a grand experiment for the composition of water. He expended no less than 25,582 cubic inches (or nearly two hogsheads) of inflammable air, and 12,457 of vital air. The first weighed 1,039 grains, and the second 6,210, amounting to 7,249 grains, and the water obtained amounted to 7,245 grains, or about three-fourths of a wine pint. The loss was only four grains. Another experiment was afterwards made by Le Fevre, in which nearly two pounds and a quarter of water was produced. The sea water contains a quantity of _salt_, but not in the same proportions every where. In the torrid zone, where otherwise, from the excessive heat, it would be in danger of putrefaction, the water is found most salt; as we advance northward its briny quality diminishes, till at the poles it is nearly gone altogether. Under the line, Lucas found that the sea comprised a seventh part of solid contents, consisting chiefly of sea-salt. At Harwich, he found it yielded 1-25 of the same matter. At Carlscroon, in Sweden, it contains 1-30 part, and on the coast of Greenland a great deal less. This gradual diminution of saltness from the equator to the pole, is not, however, without particular exceptions. The Mediterranean sea contain 1-22 of the sea-salt, which is less than the German sea contains. The saltness of some seas, or of particular parts of the same seas, may be increased, as Mr. Boyle intimates, from rocks and other masses of salt, either at the bottom of the sea, or dispersed near their shores.