104 FLORIDA GEOLOGICAL SURVEY-THIRD ANNUAL REPORT.
beyond this depth. Most of the water, however, returns to the surface after a comparatively short underground course, only a small part of it reaching to this great depth.
HYDROGEN SULPHIDE IN UNDERGROUND WATER.
The underground water of Florida is very generally impregnated with hydrogen sulphide (H2S) also known as sulphuretted hydrogen, and hydro-sulphuric acid. Water containing hydrogen sulphide is commonly known as "sulphur water." Sulphur water is especially characteristic of the areas of artesian flow. In those sections in which open porous limestone is the surface formation, hydrogen sulphide is usually absent from the first water encountered, although even here it is found to exist in the .water from the deep wells and in some springs.
Source :-Hydrogen sulphide may originate in nature in any one of several ways. The following have been suggested: (I) The decay of organic matter containing sulphur; (2) the reaction of organic matter upon sulphides or sulphates; (3) the reaction cf acids upon sulphides; (4) partial oxidization of sulphides; (5) steam passing over sulphur.
The decay of organic matter is an obvious source of hydrogen sulphide in the underground waters of Florida. Chemical analysis shows that sulphur is very generally present in Florida soils,* and apparently invariably present in muck soils. Analyses of samples of peat which is, like muck, a vegetable accumulation, will be found in the following paper on peat deposits in this volume. The amount of sulphur in the Florida peat in the dried samples varies from less than i% to over 4%Hydrogen sulphide is formed in connection with the decay of eggs. In this case the albumen of the egg, according to Ostwald, contains the sulphur.t H2S is also found escaping from sewer drains and cesspools, and is formed during the decomposition both of animal and vegetable substances. The H2S occurring in shallow springs from marsh lands is doubtless supplied largely from organic material.
The sulphur in soils is probably often present as sulphates. Thorpe states that the decay of organic matter in contact with sulphates results in the formation of H2S.4 The reaction in this
*Bulletin 43, Florida State Experiment Station, pp. 653, 657, 659, 1897.
t'Ostwald, Principles of Jnorgai ic Chemistry, page 274, 1904.
lDictionary of Chemistry, Vol. III, p. 697, 1900.