Corniferous limestone, in all of these places overlaid by the Hamilton shales. It was also shown, that in two localities in this region, viz. in Tilsonburg and at Maidstone, where the Corniferous is covered only by quaternary clays, petroleum in considerable quantities has been obtained by sinking into the limestone.* That the supplies are less abundant than in parts where a mass of shales and sandstones overlies the oil bearing limestone is explained by the fact that both the pores and the fissures in the superior strata serve to retain the oil, in a manner analogous to the quaternary gravels in some parts of this region, which are the sources of the so-called surface oil-wells. It is therefore not surprising that examples of pyroschists impregnated with oil should sometimes occur, but the evidence of the existence of indigenous petroleum, which is so clear in the various limestones, is wanting in the case of the pyroschists; although concretions holding petroleum have been observed in the Marcellus and the Genesee slates of New York. There is, however, reason to believe, as I have elsewhere pointed out, that much of the petroleum of Pennsylvania, Ohio and the adjacent regions, is indigenous to certain sandstone strata in the Devonian and Carboniferous rocks.†

At the meeting of the American Association for the Advancement of Science at Chicago, in August, 1868, in a discussion which followed the reading of a paper by myself on the geology of Ontario, it was contended that, although the various limestones which have mentioned are truly oleiferous, the quantity of petroleum which they contain is too inconsiderable to account for the great supplies furnished by oil-producing districts, like that of Ontario for example. This opinion being contrary to that which I had always entertained, I resolved to submit to examination the well-known oil-bearing limestone of Chicago.

This limestone, the quarries of which are in the immediate vicinity of the city, is so filled with petroleum that blocks of it which have been used in buildings are discoloured by the exudations, which mingled with dust, form a tarry coating upon the exposed surfaces. The thickness of the oil-bearing beds, which

• Silliman's Journal II, xlvi, 360; and Report Geol. Canada, 1866, pp. 241-250.

† Ibid, 240.

Silliman's Jour. II, xlvi, 355.

are massive and horizontal, is, according to Prof. Worthen, from thirty-five to forty feet, and they occupy a position about midway in the Niagara formation, which has in this region a thickness of from 200 to 250 feet. As exposed in the quarry, the whole rock seems pretty uniformly saturated with petroleum, which exudes from the natural joints and the fractured surfaces, and covers small pools of water in the depressions of the quarry. I selected numerous specimens of the rocks from different points. and at various levels, with a view of getting an average sample, although it was evident that they had already lost a portion of their original content of petroleum. After lying for more than a year in my laboratory they were submitted to chemical examination. The rock, though porous and discoloured by petroleum, is, when freed from this substance, a nearly white, granular, crystalline and very pure dolomite, yielding 54.6 p. c. of carbonate of

lime.

Two separate portions, each made up of fragments obtained by breaking up some pounds of the specimens above mentioned, and supposed to represent an average of the rock exposed in the quarry, were reduced to coarse powder in an iron mortar. Of these two portions, respectively, 100 and 138 grammes were taken, and were dissolved in warm dilute hydrochloric acid. The tarry residue which remained in each case, was carefully collected and treated with ether, in which it was readily soluble with the exception of a small residue. This, in one of the samples, was found equal to 40 p. c., of which 13 was volatilized by heat with the production of a combustible vapour having a fatty odour; the remainder was silicious. The brown etherial solutions were evaporated, and the residuum freed from water and dried at 100°C, weighed in the two experiments equal to 1·570 and 1·505 per cent. of the rock, or a mean of 1.537. It was a viscid reddish-brown oil, which, though deprived of its more volatile portions, still retained somewhat of the odour of petroleum which is so marked in the rock. Its specific gravity as determined by that of a mixture of alcohol and water, in which the globules of the petroleum remained suspended, was 935 at 16°C. Estimating the density of the somewhat porous dolomite at 2-600, we have the equation 935 2-600: 1-1537: 4-26; so that the volume of the petroleum obtained equalled 4-26 per cent of the rock. This result is evidently too low for two reasons; first, because the rock had already lost a part of its oil, while in the

quarry, and subsequently, before its examination; and secondly, because the more volatile portions had been dissipated in the process of extraction just described.

In assuming 100-00 parts of the rock to hold 4.25 parts by volume of petroleum, we are thus below the truth in the following calculations. A layer of this oleiferous dolomite one mile (5280 feet) square, and one foot in thickness will contain 1,184,832 cubic feet of petroleum, equal to 8,850,069 gallons of 231 cubic inches, and to 221-247 barrels of forty gallons each. Taking the minimum thickness of thirty-five feet, assigned by Mr. Worthen to the oil-bearing rock at Chicago, we shall have in each square mile of it 7,743,745 barrels, or in round numbers seven and three quarter millions of barrels of petroleum. The total produce of the great Pennsylvania oil-region for the ten years from 1860 to 1870 is estimated at twenty-eight millions of barrels of petroleum, or less than would be contained in four square miles of the oil-bearing limestone band of Chicago.

It is not here the place to insist upon the geological conditions which favour the liberation of a portion of the oil from such rocks, and its accumulation in fissures along certain anticlinal lines in the broken and uplifted strata. These points in the geological history of petroleum were shown by me in my first publications already referred to, March and July, 1861, and independently, about the same time, by Prof. E. B. Andrews in this Journal for July, 1861.*

The proportion of petroleum in the rock of Chicago may be exceptionally large, but the oleiferous character of great thickness of rock in other regions is well established, and it will be seen from the above calculations that a very small proportion of the oil thus distributed would, when accumulated along lines of uplift in the strata, be more than adequate to the supply of all the petroleum wells known in the regions where these oil-bearing rocks are found. With such sources existing ready formed in the earth's crust, it seems to me, to say the least, unphilosophical to seach elsewhere for the origin of petroleum, and to imagine it to be derived by some unexplained process from rocks which are destitute of the substance.

Sill. Jour. II, xxxii, 85. See also papers on the subject by him and by Prof. Evans, Ibid. II, xl. 33, 334; and one by the author, II, xxxv, 170; also Report Geol. Survey of Canada, 1866, pp. 256-257.

GEOLOGICAL SURVEY OF CANADA.

ALFRED R. C. SELWYN, DIRECTOR.

The Report of Progress from 1866 to 1869 is a bulky volume of 475 pages, with five maps, containing the results of a large amount of work ranging over the whole vast territory from Lake Superior to Nova Scotia inclusive. It embraces the following documents:

1. Letter of Mr. Selwyn introducing the Report.

2. Report of Sir W. E. Logan on part of the Coal-field of Pictou, Nova Scotia.

3. Report of Mr. Edward Hartley on part of the same Coalfield.

4. Report of Mr. R. Bell on the Manitoulin Islands.

5. Report of Mr. James Richardson on the South Shore below Quebec.

6. Report of Mr. Henry G. Vennor on Hastings County, Ontario.

7. Report of Mr. Charles Robb on part of New Brunswick. 8. Report of Dr. T. Sterry Hunt on the Goderich Salt Region, and on Iron and Iron Ores.

9. Report of Mr. James Richardson on the North Shore of the Lower St. Lawrence.

10. Report of Mr. Robert Bell on Lakes Superior and Nipi

gon.

11. Reports of Mr. Edward Hartley on the Coals of Nova Scotia.

12. An Appendix, containing lists of Plants by Dr. John Bell, and a Note on the Nipigon Region by Sir W. E. Logan. Out of such a mass of matter it would be almost in vain to attempt to select specimens of each of the separate treaties of which the Report consists. A melancholy interest attaches to that part of it which bears the name of Mr. Edward Hartley, a young man of great ability and information, and high promise, and whose work in this Report would alone be sufficient to give him a permanent place among our scientific men, but who was cut off by death in the midst of his practical and useful labours. From his elaborate survey of part of the great Pictou coal-field, we may extract the part having reference to areas, in which Canadian capitalists are largely interested:

"The Acadia Coal Company own three mining rights, which are as follows:

The Fraser area, south of the General Mining Association's area; the Carmichael area, southwest of the General Mining Association's area; and No. 3 area, lying to the south of the Fraser area.

FRASER AREA.

Workings have been carried on for many years upon the Fraser area; first by the General Mining Association, and more lately by Mr. J. D. B. Fraser, of Pictou, from whose possession it passed by lease to the present company.

Attempts have been made by former owners to work the Deep Seam on the western portion of the area at the McKenzie pit, and a slope has also been driven some distance on the crop of the Third coal seam, both of which workings are now abandoned, and therefore require no special description. The present workings are confined to the McGregor seam and two openings on the Oilcoal.

McGregor Colliery.

In the McGregor colliery the openings consist of No. 1, an adit, No. 2, a slope, and No. 3, a pair of slopes.

Adit No. 1 was opened by the General Mining Association on the left bank of Coal Brook, near the crossing of the Middle River road, and driven N. W. a distance of about 800 yards. The seam was irregularly worked by the General Mining Association and Mr. Fraser, but is, I believe, for the present abandoned.

Slope No. 2 is a single slope to the lower level of No. 3 slopes, and was formerly the working slope, but is now used only as a travelling way. It stands on the left bank of Coal Brook near the mouth of No. 1. Slopes No. 3 are the principal working. Their situation is 170 yards S. E. of No. 2, on the right bank of the brook. Their total depth is 510 feet. Main levels extend 260 yards N. W. and but 20 yards in the contrary direction. The dimensions of the slope are: Drawing slope (a double railway track) 9 feet post, 9 feet cap and 14 feet ground sill. The tracks are all of T iron 25 lbs. to the yard. The second slope, a travelling way for horses and men, is separated from the draw