, situated near an extinct volcano, where a perpetual gas
flame in a neighboring chapel and other symptoms indicate that
petroleum is not far off. While engaged in studying the geological
conditions of this mine, the author observed that Dr. Christoff
Bischoff records in his writings that he had produced sulphur in his
own laboratory by passing hot volcanic gases through chalk, which,
when expressed in a chemical formula, leads at once to the postulate
that, in addition to sulphur, _ethylene_, and all its homologues
(C_{n}H_{2n}), which are the oils predominating at Baku, would be
produced by treating:

2, 3, 4, 5 equivs. of carbonate of lime (limestone) with
2, 3, 4, 5 " sulphurous acid (SO_{2}) and
4, 6, 8, 10 " sulphureted hydrogen (H_{2}S);

and that marsh gas and its homologues, which are the oils
predominating in Pennsylvania, would be produced by treating:

1, 2, 3, 4, 5 equivs. of carbonate of lime with
1, 2, 3, 4, 5 " sulphurous acid and
3, 5, 7, 9, 11 " sulphureted hydrogen.

Thus we find that:

Carbonate of lime, 2CaCO_{3}, } { 2(CaSO.H_{2}O) (gypsum),
Sulphurous acid, 2SO_{2}, and } yield { 4S (sulphur), and
Sulphureted hydrogen, 4H_{2}S, } { C_{2}H_{4}, which is
{ _ethylene_.

And that:

Carbonate of lime, CaCO_{3} } { (CaSO_{4}.H_{2}O) (gypsum),
Sulphurous acid, SO_{2}, and } yield { 3S (sulphur) and
Sulphureted hydrogen, 3H_{2}S, } { CH4, which is marsh gas.

So that these and all their homologues, in fact petroleum in all its
varieties, would be produced in nature by the action of volcanic gases
on limestone.

But much the most abundant of the volcanic gases appear at the surface
as steam, and petroleum seems to have been more usually produced
without sulphurous acid, and with part of the sulphureted hydrogen
(H_{2}S) replaced by H_{2}O (steam) or H_{2}O_{2} (peroxide of
hydrogen), which is the product that results from the combination of
sulphureted hydrogen and sulphurous acid:

(H_{2}S + SO_{2} == H_{2}O_{2} + 2S).

It is a powerful oxidizing agent, and it converts sulphurous into
sulphuric acid. Thus:

CaCO_{3} } { CaSO_{4}.H_{2}O (gypsum)
H_{2}S, } yield { and
2H_{2}O, } { CH_{4}, which is marsh gas.

And

2CaCO_{3}, } { 2CaSO_{4}.H_{2}O
2H_{2}S, } yield { and
2H_{2}O_{2}, }