whose hands the property has now passed, have commenced a series of energetic and well directed explorations at various points upon the hill, with a view to the discovery of additional deposits of ore. At one of these new openings, distant at least 500 feet from the limit of the old workings, and not more than 200 feet from the summit of the hill, a deposit of the richest description of the softer kind of cinnabar has been discovered, which, so far as hitherto explored, has a linear extent of at least 70 or 80 feet, and in point of richness has never been surpassed by any similar discovery in the past history of the mine. A charge of 101,000 pounds, of which 70,000 were composed of this rich ore, 31,000 pounds of "granza," or ordinary ore, and 48,000 pounds of adobes, worth 4 per cent, making a total charge of 105,800 pounds, yielded on the day of our visit, 460 flasks of mercury at 76 pounds to the flask. This yield is almost without parallel in the history of the mine. The only preparation which the ores undergo, preparatory to reduction, consists of hand-breaking, or "cobbing," for the removal of the unproductive rock. The small ores and dirt hoisted from the mine are made into adobes," or sun-dried bricks, sufficient clay for the purpose being associated with the ore. The object of these "adobes" is to build up the mouths of the furnaces to sustain the load of richer ores. No flux is employed, there being sufficient lime associated with the ores to aid the decomposition of the sulphurets. The furnaces are built entirely of brick, in dimensions capable of holding from 60,000 to 110,000 pounds, according to the character of the ores employed. The chambers are fired from a lateral furnace, fed with wood, and separated from the ore by a wall pierced with numerous openings by the omission of bricks for that purpose. Connected with the furnace is a series of lofty and capacious chambers, also of masonry, through which the whole product of combustion is compelled to pass alternately above and below, from chamber to chamber, until all the available mercury is condensed. The draft from these furnaces is carried by inclined stacks up to the top of a lofty hill several hundred feet distant; and here the sulphurous acid and other effete products of the furnace are discharged. Formerly, no precautions were taken to prevent the escape of mercury through the foundations of the furnace to the earth beneath: now, the furnaces stand upon double arches of brick-work, and plates of iron are built into the foundations, so as to cut off entirely all descending particles of the metal and turn them inward. To be convinced of the importance of this precaution, it is sufficient to watch the operation of the furnace for a few moments, when an intermittent AM. JOUR. SCI.-SECOND SERIES, VOL. XXXVIII, No. 113.—SEPT., 1864. stream may be seen to flow into a reservoir provided for it, and which by the former process was completely lost in the earth. On taking up the foundations of some of the old furnaces, within the last two years, the metal was found to have penetrated, or rather permeated, completely through the foundation and clay of the substructure down to the bed-rock beneath, a depth of not less than 25 or 30 feet. Over 2,000 flasks of mercury were thus recovered in a single year from the foundations of the two furnaces. This loss is entirely avoided by the improved construction which has been adopted. The whole process of reduction is extremely simple, the time occupied from one charge to another being usually about seven days. The metal begins to run in from four to six hours after the fires are lighted, and in about sixty hours the process is completed. The metal is conducted through various condensing chambers by means of pipes of iron, to a "crane-neck," which discharges into capacious kettles. It undergoes no further preparation for market, being quite clean from all dross. Deducting 2 years, during which the mines were in a state of inactivity, pending the decision of the law-suit, the average monthly product for 12 years has been not far from 2,500 flasks, of 76 pounds each, of mercury. The selling price in San Francisco is, at present, and has been for some time past, 75c. per pound, while in London and New York it has ranged from 40 to 50c. per pound. San Francisco, May, 1864. ART. XIX.-Observations on a Seam of Coal; by Prof. E. B. ANDREWS, Marietta College, Ohio. THE seam of coal here described is located in the northern part of Washington Co., Ohio. It extends through the hills for several miles, and is generally of workable thickness. On Bear Creek, a small tributary of the Muskingum river, which latter stream is rendered navigable by large dams and locks, the coal is five feet in thickness. To the south the coal disappears, and evidence will presently be given to show that the original coal marsh was in that direction, skirted by open water. The geological position is near the top of the Coal Measures. I know of no other seam of coal of economic value above it in our Ohio rocks, although we find perhaps two hundred feet of unproductive sandstones and shales still higher. It is about sixty feet higher in the series than a peculiar group of limestone strata, with which is associated a seam of coal now worked at Coal Run on the Muskingum river. This group is very persistent, and, after showing itself over a considerable part of Washington County, dips below the Ohio river to the northeast and reappears in the vicinity of Wheeling, W. Virginia, where its accompanying coal is extensively mined. In this connection it may be remarked, that there is great confusion among our geologists relative to the equivalency of the Pittsburg, Wheeling, and Pomeroy seams of coal. Dr. Caleb Briggs, who was connected with the early surveys of Western Virginia and Ohio, regards the three seams as equivalent; while Lesquereux makes the Pittsburg and Wheeling seams equivalent, to which he adds another, in a seam of coal at Athens, Ohio. My own investigations have led me to believe the Wheeling and Pomeroy seams to be entirely distinct, while the Athens coal is probably the continuation of the Pomeroy seam. The Athens coal is probably the same with the Federal Creek Coal, (Athens Co.) which, by all our Ohio geologists, is regarded as the continuation of the Pomeroy seam. The Pomeroy seam, as traced by myself, from Federal Creek into the northwestern part of Washington County, is found to be from sixty to seventy feet above the very limestone group which is so persistent, and which carries with it the Coal Run and Wheeling seam of coal. The Pomeroy seam sweeps around through the northern and eastern parts of Washington County, and is everywhere from fifty to seventy feet above the limestone group. Doubtless the seam of coal which is found in the hills above the Wheeling seam at Belleair (near Wheeling), is the equivalent of the Pomeroy coal. The Bear Creek coal, which I propose to examine, is without doubt the geological equivalent of the Pomeroy seam. It is, however, greatly modified in structure by causes which I shall hereafter explain. Before the Bear Creek coal disappears to the south, there is evidence of a struggle in that direction between the vegetation and the water. The coal-marsh was repeatedly flooded, and over the vegetation thick deposits of sediment were made which are now fire-clay. We have these repeated alternations of coal and clay until, at last, the coal disappears, and we reach a region of unbroken water. There is nothing peculiar in the rocks. associated with this coal. Above the coal is a thin stratum of bituminous slate. Above the slate several feet of fire-clay, and above the clay a heavy sandrock. Below the coal is fire-clay, and below that a considerable development of sandstones and shales. 1. Thick, firm sandstone. Fire-clay, Coal. Fire-clay. Sandstones and shales. The coal was analyzed by Dr. J. S. Newberry and gave: Volatile matter, 49 to 51 per cent. 66 66 3 " 5 Fixed carbon, Ash, Probably this percentage of ash is a little below the average for the whole seam. The coal is hard, and breaks with an unusual conchoidal fracture, resembling cannel coal. The appearance of the laminations as seen on the surface of the polished vertical planes, resembles varnish spread with a coarse brush, thus giving a peculiar streakiness to the surface. These laminations often show themseves to be immeasurably thin layers of sedimentary matter. In the fracture these layers present the appearance of exquisitely-fine steel medal-ruled engraving. It is doubtless to these peculiar laminae that the coal owes the property of parting with remarkable readiness with its gas or hydro-carbons, for the coal is very rich in gas and burns with remarkable freedom. In the grate it differs from the Wheeling coal, as dry wood differs from wet green wood. Why the presence of these laminæ of sedimentary matter-thinner than any tissue paper-should thus facilitate the production of gas, a fact which I have observed in some cannel coals, has not been explained so far as I know. Besides these peculiar laminations, there are the usual ones, which most geologists regard as produced by the different increments of vegetable matter, and showing perhaps periodicity in the growth and falling of the leaves and fronds of the coal vegetation. The Pittsburg coal exhibits this class of laminations in smooth and highly polished horizontal surfaces, and it is by these that this coal is readily distinguished from other Western coals. In the Bear Creek coal we find also lamina of mineral charcoal. This is sometimes found in plates one-fourth of an inch in thickness. It exhibits a fibrous, woody structure, and is very soft and easily reduced to powder. Whether this charcoal is produced by some peculiar property in the original vegetable matter, which did not permit the usual bituminization, or the bitumen has been subsequently removed by great pressure, leaving the fibres dry like the pressed stalks of sugar cane, it is perhaps impossible to determine. The first class of laminæ, those having a sedimentary appearance, doubtless tells a tale of water, and indicates that the vegetation grew where it was very marshy and constantly inundated. This water, however, contained only the slightest possible amount of impalpable sediment, and could scarcely have been much discolored. This marshy character of the coal field and the overflow of water doubtless caused an unusual softening and maceration of the fallen vegetable matter, and produced the cannel-like character of the coal. But while the coal marsh was ordinarily more or less covered with comparatively pure water, at one time it was flooded by more turbid water, which left a distinct earthy deposit. This thin slaty streak in the coal, now black and highly bituminous, is evenly distributed over a large area, and indicates a general overflow. Another interesting feature of the Bear Creek coal is the presence, in various parts of the seam, of drifted and beach-worn wood. This is generally found in small fragments with the ends rounded, as if long water-tossed. Though now changed into sulphuret of iron, they show plainly a woody structure, and are entirely unlike the flat plates of sulphuret of iron which are formed within all coals by chemical affinity. I have found them showing the bark-markings of the original tree. 2. In some instances they are sticks six or eight inches long, an inch and a half in diameter, and rounded at the ends. They are not confined to any particular part of the seam, but may be met with any where, even in the very purest portions of coal. This would indicate that the coal was formed under circumstances allowing these vegetable waifs to be floated in and lodged among the vegetation. But the water on which they were borne could have been only slightly charged with sediments, as no such sediments, with the exceptions of the extremely thin lamina previously alluded to, are found in the coal. I doubt whether these bits of drifted wood are to be found in the coal very far inland from the water edge of the coal marsh. I have not noticed them in the same seam of coal where it is mined, a few miles northeast of Bear Creek. There is, moreover, evidence to show that the coal changes in character as it recedes from the water's edge of the original marsh. It becomes more soft and caking, and less like cannel in fracture and behavior in the fire. These facts are interesting, as tending to verify Dr. Newberry's theory, that cannel coal is produced by the action of water in rendering the vegetable matter more soft and pulpy. Vertical planes.-The existence of vertical planes in all coal has long been known. I have improved many opportunities of studying these planes, and have, so far as our Western coal fields are concerned, verified a conclusion which I presented in a paper read before the American Association for the Promotion of Science, at the meeting in Springfield, Mass., viz: that these planes have a uniform direction-nearly east and west. I have examined seams of coal in all parts of the Coal Measures, from the bottom to the top, as well as seams far apart geographically, and have invariably found the general direction of these planes the same. So confident have I become in this conclusion, that, |