CORRESPONDENCE

Poverty Bay Herald, Volume VII, Issue 1085, 4 May 1880, Page 2

CORRESPONDENCE

PETROLEUM.

[To the Editor of the Herald.]

Dear Sir, — I have much pleasure in acceding to j 7 our request to write a few short articles on Petroleum, a subject at the .present time of great interest to the inhabitants of this district. I am, Sir, Yours faithfully, J. H. Stubbs.

In order to bring the subject clearly before your readers, I propose to divide it into four parts : — 1. Its source or oi'igin. 2. Location and statistics. 3. Mode of extraction and purification.

4. Utilization (present and future),

Its Source oe Origin,

Petroleum, as a Mineral Oil, has been known and used from the earliest times. Heridotus, writing 440 years 8.C., speaks of it as being obtained from a place called Adderica, near the town of Susa. The Persians called it " Rhadinace •" the Arabs " Napth," from whence we get our word Naptha. Baku, near the Caspian Sea, was the head-quarters of the ancient sect of Fire-worshippers, the origin of their perpetual fire was Petroleum welling up through a crevice in the rock. In the early times it was principally used for medicinal purposes. It is what is known chemically as a hydrocarbon. Its general composition is C.24, H. 24, that is carbon and hydrogen in equal proportions. Retain the quantity of carbon and decrease the hydrogen, and a corresponding increase of density is observed. Gradually you get Bitumen, Asphalt, Resinous Lignite, and lastly Bituminous coal ; thus proving to a certain extent the identity of source, although even at the present time geologists and chemists differ in their theories. Were the Petroleum produced of the same quality, and the strata from whence they are derived, of the same character there would be no difficulty in proving their origin, but tney differ materially. It is advanced that the Petroleums of Canada are chiefly derived from the decomposition of vast numbers of marine animals, plants, molluscs, etc. ; and the theory is not unreasonable, as the oil is chiefly obtained from the older Silurian rocks and corniferous limestone which contain exclusively marine remains, and is not permeable to liquids from without. In distillation, the Canada Petroleum yields Acroline, a pungent oil, which is only obtained from animal oils and fats — chiefly from fish oil. The Canadian wells also yield

large quantities of salt water. The bituminous odour evolved by nearly all fossiliferous limestones, as for instance the Upper Silurian and cai'boniferous limestones of England, which contain no land plants, all of which facts still further sustain the above theory.

On the other hand, m.my scientists hold the opinion that Petroleum is formed during the transformation of woody or vegetable fibre into coal or lignite. According to Dr. Sterrv Hunt, who has specially studied the subject, it would appear that the separation of vast quantities of carbon combined with hydrogen is the firststage in carbonaceus metamorphism, and that under favourable condition (that is, when kept from the access of air, as in the cavities of limestones or in sandstone or shale), the gases of this element, under great pressure, are i condensed and thus produce hydrocarbon (Petroleum). The operation is a decomposing and combining one, and the new combinations formed during the transmutation of wood into coal have a close analogy to those produced during the distillation of wood without the admission of air. That coal is derived from vegetable substances is undoubted, from the expulsion of oxygen, carbon, and hydrogen from vegetables, until true coal is formed. |Heat has not been absolutely necessary, although it has probably played an important part in the chemical changes that produced that result. The condensation of carbon and hydrogen producing oil, and the fact of coal and shales giving out these elements before complete carbonisation, and the tendency of these gases and oil to diffuse themselves in other absorbed strata, are good reasons for finding oil in formations bearing no trace of vegetable. One writer advances the theory | that " The Petroleum of Pennsylvania arises from the distillation by subterranean heat of the hydrocarbon agents resident in the carbonaceous strata underlying the oil region." Another writer says : " That the great beds of anthracite eval of Pennsylvania, on the southerly slope of the Allighannies, are merely the residuary coke, as it were, of a distilling process which has converted their bituminous matter into oil, and distributed it by some convulsion of nature through the formation beyond the mountain range."

Du. Senft, a German writer, has propounded a theory, which may come very near the truth in explaining why in certain cases coal is formed and in others bituminous shale. It is that the carbonaceous substance produced iv peatbogs has ihe,. power o£a,bsorbIng and fixing carbu retted an 3 sulphuretted hydrogen. Supposing in a sea bed the amount of decomposing organic mattex*, marine plants, molluscs, etc., to be small as compared with the accompanying mineral matter, (lime, silica, clay, etc) ; the hydrocarbons formed would be liable to escape and remain isolated as Petroleum ; but in the case of a great forest growth or peat bog decomposing under water, the hydrocarbons separated would be liable to be re-absorbed by the large excess of resident (carbon present, and would thus form bituminous coal.

So far, however, as research has gone, it has failed to present a theory acceptable to all. It cannot be denied that all Petroleum could not have had precisely the same origin, and that a theory which is applicable to one district, would not apply to

another.