CHEMICAL RELATIONS BETWEEN WATER AND HYDROCARBONS. 97 
sulphate is more readily reduced. The experiments of the earlier 
y orkers are discredited by the fact that no precautions were taken 
to exclude bacteria, and certain more recent attempts proved unsuc¬ 
cessful, but recently Kharitschoff 1 has published a note on some 
simple experiments that were at least partly successful. He studied 
mixtures of equal volumes of 10 per cent sodium sulphate solution 
and kerosene or benzene under different conditions of temperature 
and pressure. Cadmium chloride was used to indicate the formation 
of sulphide. Three samples exposed to direct sunlight for six months 
at ordinary temperatures showed no sign of reduction. Other sam¬ 
ples, sealed and heated for 420 hours on a water bath, under which 
conditions a pressure of not less than three atmospheres must have 
been developed, showed a very faint coloration due to the formation 
of a trace of sulphide. In still other samples left open and heated 
for 420 hours at 96° C. some sulphide was formed. A solution of 
magnesium sulphate mixed with kerosene and heated in the open 
for 420 hours underwent somewhat more reduction than the solu¬ 
tion of sodium sulphate. Kharitschoff concludes from these experi¬ 
ments that the reduction of sulphate can be accomplished by hydro¬ 
carbons, but that high pressure and temperature during a long period 
of time are necessary to insure complete reduction. 
If it be admitted that the reduction of sulphate is accomplished 
directly by the constituents of oil it must still be recognized that the 
reaction as generally written, involving methane, is improbable. 
Methane, being itself a decomposition product, is the most stable 
member of the paraffin series, which are the most inert of the hydro¬ 
carbons; and although methane becomes much more active at higher 
temperatures and pressures it seems that the reduction of a sulphate 
solution would be accomplished less readily by this hydrocarbon 
than by others. The different members of the hydrocarbon series 
probably react with sulphate solutions in different degree, but this 
phase of the subject has apparently not been investigated. The un¬ 
saturated chain compounds, such as the olefines, acetylenes, and ter- 
penes, doubtless behave in different manner from the paraffins, the 
naphthenes, or the aromatic hydrocarbons, not only in the ease of 
reaction but in the stages involved. In the reactions between some 
substances hydrolysis is probably important, and in those between 
other substances the action of oxidizing agents may enter. It is 
quite possible that certain constituents of the oil other than true 
hydrocarbons are active in the reduction' of sulphate solutions, 
although for the sake of brevity the term hydrocarbon is used in this 
report to include all oil constituents. In any event, the reaction as 
written by Hofer (p. 94) can be considered only a condensed repre- 
i Kharitschoff, K. V., The waters in petroleum wells: Petroleum Rev., vol. 29, p. 368, 1913. 
60439°—Bull. 653—17-7 
