CHEMICAL RELATIONS BETWEEN WATER AND HYDROCARBONS. 95 
is due not to the mere presence of dead organic matter but to the 
vital processes of microorganisms. Numerous observers have since 
studied these creatures, whose functions are diverse 1 and whose 
importance from the standpoint of geochemistry appears to be consider¬ 
able. It has been found that certain bacteria have the function of re¬ 
ducing sulphate to sulphite or thiosulphate and that others reduce 
oxygenated sulphur compounds to hydrogen sulphide. 2 On the other 
hand, certain bacteria can exist only in solutions containing hydrogen 
sulphide, which they oxidize and secrete as sulphur. This sulphur is 
further oxidized in the course of metabolism to sulphate, but the 
excess of sulphur remaining in the organism after death may accumu¬ 
late to form deposits of crystalline sulphur. 3 In general, the sulphide- 
producing bacteria are anaerobic, being able to exist in the absence 
of air, whereas those which secrete sulphur are probably aerobic. 
The hydrogen sulphide in many natural waters is thus doubtless 
derived from aqueous sulphate solutions by the action of bacteria. 
The action of similar organisms in ocean water has also been 
studied. Van Delden, 4 in experimenting with a species that inhabits 
the estuaries on the coast of Holland, finds that these bacteria 
liberate in 27 days 843 milligrams of hydrogen sulphide per liter, 
which represents the reduction of 1,984 milligrams of sulphur trioxide. 
In this experiment he used sea water, to which was added a little 
potassium phosphate and organic matter; in another experiment 
with the same bacteria he used a prepared solution containing 
slightly more sodium chloride and more sulphate than sea water, 
and found that in 19 days 1,030 milligrams of hydrogen sulphide, 
equivalent to 2,424 milligrams of sulphur trioxide, were liberated. 
In the latter experiment the amount of sulphate reduced slightly 
exceeds that present in normal sea water. Van Delden notes also 
that the activity of this species increases with the concentration of 
sodium chloride up to 60,000 parts per million, but that the addi¬ 
tion of more sodium chloride produces a marked diminution in their 
activity. 
Hydrogen sulphide has been repeatedly observed in sea water 
and has been quantitatively determined by several observers. 
Lebedinzeff 5 & finds that water from a depth of 8,290 feet in the 
1 Winogradsky, Sergius, Ueber Schwefelbacterien: Bot. Zeitung, Nos. 31 to 37, 1887. 
2 See, for example, Beyerinck, M. W., Ueber Spirillum desulfuricans als Ursache von Sulfatreduction: 
Centralbl. Bakteriologie, Band 1, Abt. 2, pp. 1-9, 49-59, 104-114, 1895. Also Saltet, R. H., Ueber Reduk- 
tion von Sulfaten in Brackwasser durch Bakterien: Idem, Band 6, Abt. 2, p. 648,1900. 
a For a summary see Stutzer, O., Die Wichtigsten Lagerstatten der Nicht Erze, Berlin, 1911; Phalen, 
W. C., The origin of sulphur deposits (translation from Stutzer’s work): Econ. Geology, vol. 7, pp. 732- 
743, 1912. 
4 Van Delden, A., Beitrag zur Kenntnis der Sulfatreduktion durch Bakterien: Centralbl. Bakteriologie, 
Band 11, Abt. 2, pp. 92-94, 113-119, 1903. 
& Lebedinzeff, A., Vorlaufige Mitteilung iiber den chemischen Untersuchungen des Schwarzen und 
Asowischen Meeres in Sommer 1891: Soc. Naturalistes ft Odessa Trav., vol. 16, fasc. 2, p. 149, 1891; abstract 
in Roy. Geog. Soc. Proc., new ser., vol. 14, p. 461, 1892. 
