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}, } { C_{2}H_{4}, which is _ethylene._ Tables are given showing the formulae for the homologues of ethylene and marsh gas resulting from the increase in regular gradation of the same constituents. _Formulae Showing how Ethylene and its Homologues (C_{n}H_{2}{n}) are Produced by the Action of the Volcanic Gases H_{2}S and H_{2}O_{2} on Limestone._ Carbonate Sulphureted Peroxide of Ethylene and of lime. hydrogen. hydrogen. Gypsum. its homologues.