THE ARTESIAN WATER SUPPLY OF EASTERN FLORIDA.

This method of freeing water from an excess of H2S gas is a common practice wherever sulphur water is used for domestic purposes. Wherever porous limestone lies at or near the surface the sulphur gas which the water may have contained will find a ready means of escape. In other parts of the State where compact and impervious formations rest upon the limestone, the gas is prevented from escaping and suphur water is obtained.
AMOUNT OF HYDROGEN SULPHIDE INFLUENCED BY PRESSURE.
The quantity of H2S gas which the water is able to hold in solution under these conditions, is determined by the pressure. The law of the solubility of gases in liquids is as follows: The quantity of the gas which the liquid is able to dissolve is directly proportional to the pressure on the gas. In the open, porous limestone with no confining stratum above, the water at the top of the underground water level is merely under atmospheric pressure. After passing the underground water level, however, the pressure increases rapidly. The increase of pressure is not simply that due to the atmosphere, but that due to the weight of the overlying column of water plus the atmosphere. According to Van Hise:* .'The pressure which really is determinative as to the amount of gas %,vhich may be held in solution is that of a column of water extending to the free surface, plus the atmospheric pressure." From this law it follows that water at a great depth and under great pressure is capable of holding a large quantity of hydrogen sulphide in solution. When brought to the surface the pressure is relieved and the gas rapidly escapes. The artesian waters in the flowing areas of the State are under considerable pressure, thus enabling them to hold a large quantity of hydrogen sulphide as well as a high proportion of mineral solids in solution.
In order that the deep waters may hold large quantities of H2S in solution it is necessary that the gas be available. This implies that the gas in the artesian and other deep waters originates at some considerable depth rather than at or near the surface.
ARTESIAN WATER.
The term "artesian" has been variously used by different writers. Flowing Wells first became well known in the province of Artios, France, and hence were called "artesian wells," and their water "artesian water." The first meaning of "artesian well" was
*L. c., page 70.

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