THE ARTESIAN WATER SUPPLY OF EASTERN FLORIDA. i07 
This method of freeing water from an excess of H2S gas is a 
common practice wherever sulphur water is used for domestic pur¬ 
poses. 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 lime¬ 
stone 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 
which may be held in solution is that of a column of water ex¬ 
tending 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 sul¬ 
phide in solution. When brought to the surface the pressure is re¬ 
lieved and the gas rapidly escapes. The artesian waters in the flow¬ 
ing 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. 
