Thus, while Åkerman finds that my bisilicates have higher total heat of solidification than this of Gredt's, I find lower melting-points than Gredt, and this though I sought a higher degree of liquidity, and hence should have found a higher melting-point, than Gredt, who sought rather the softening- than the melting-point.

Åkerman, indeed, thinks Gredt's results too high, for they can be reconciled with his own only by assuming values for the specific heat which he thinks too low.* Akerman is probably right, though we can hardly locate the sources of our discrepancies confidently yet.

CRYSTALLINE MAGNETITE IN THE PORT HENRY, NEW YORK, MINES.

BY JOHN BIRKINBINE, PHILADELPHIA, PA.

An unusually large number of crystals of magnetite obtained in the exploitation of a deposit of magnetic iron-ore of remarkable purity, encouraged the preparation of this paper, and its presentation at this time, that the matter might go on record in the Transactions. To make this record more complete, a preliminary statement is offered concerning the district and locality in which the ore is found.

To the northeastern portion of the State of New York the United States is indebted for a large percentage of the iron-ore which has assisted in developing the resources and industries of the nation. As early as 1804, iron-ore was mined between Lake Champlain and the Adirondack mountains, and this district has since been an important and continuous contributor to our iron-ore supply.

The production of the Lake Champlain district for the last eleven years is as follows:

* Stahl und Eisen, vol. x., p. 424, May, 1890. From Jernkontorets Annaler, 1889, v. and vi.

In a paper upon the "Prominent Sources of Iron-Ore Supply,"* I drew attention to the importance of the iron-ore deposits of this district; and I quote from that paper, supplementing the figures of production there given by adding the estimated output up to the close of 1889.

Some of the Lake Champlain deposits have been operated for nearly a century; and the total output of this district to and including the year 1889 cannot be determined, but it is estimated at 15,750,000 gross tons. The largest producers are the mines at Mineville, near Port Henry, New York, from which 9,530,000 tons are estimated to have been obtained.

The total product of the Lake Champlain district in 1888 and 1889 was obtained from the following deposits:

Concerning the magnetites of northern New York, Prof. J. C. Smock, says: t

"The Adirondack region, the great mountain plateau of northern New York, is bounded by the valleys of Lake Champlain on the east, of the St. Lawrence river on the north and northwest, of Black river on the west, and the Mohawk on the south. Its area has been estimated to be at least 10,000 square miles. Dr. Emmons, in his survey of the second geological district, described the rock formations of this territory as gneisses and hypersthene rock principally; and the former he regarded as the prevailing rock, excepting in a large triangular area in Essex county, where the outcropping rocks are hypersthene. The gneissic rocks resemble closely the rocks of the Highlands of the Hudson, and they have been recognized by geologists generally as the Lower Laurentian.

"The so-called 'hypersthene rocks' of Dr. Emmons consist of labradorite and pyroxene or labradorite with hypersthene and some pyroxene, and hence are often designated as a Labrador series. In an article on the 'Laurentian Magnetic IronOre Deposits in Northern New York," Charles E. Hall has grouped the magnetites in three series or horizons; the lowest, the Laurentian magnetites; second, the Laurentian sulphurous ores; and highest, the Labrador group, with its titaniferous ores."

Prof. George W. Maynard, in an elaborate paper on "The IronOres of Lake Champlain," published in the Journal of the British Iron and Steel Institute, vol. i., 1874, p. 114, says that "mineralog

* Trans., xvii., 715.

† Bulletin of the New York State Museum, June, 1889.

ically the ores of the Lake Champlain district may be considered under the following heads: The unaltered magnetites; the peroxidized magnetites (martites); the titaniferous magnetites. . . . The largest occurrence of the unaltered and titaniferous magnetites is in Essex county, the peroxidized ores being for the most part confined to Clinton county."

Prof. Smock states that " magnetite is one of the common minerals in the Adirondacks, and is widely distributed, both as a constituent or accessory mineral in rocks, and in beds of workable extent."

The tenth United States census reported 731,992 tons from all the mines in the Adirondack region.*

At present the producing mines of the Adirondack region may be grouped in three districts, those of Essex, Clinton, and Warren counties, respectively. The deposit to which this paper refers is in Essex county; and the mines in this county may be properly subdivided into two groups, viz., the "Port Henry" and the "Crown Point." The names indicate the towns on Lake Champlain from which the product of the mines is shipped. In both cases, the ore is obtained away from, and at considerable elevation above, Lake Champlain, railroads connecting the mines with the Lake ports.

Five miles northwest of, and 1200 feet above, Lake Champlain at Port Henry, in the town of Moriah, Essex county, is the village of Mineville, where are located the operations of the Port Henry IronOre Co., and those of Witherbees, Sherman & Co., recognized in the trade as the "Port Henry mines." At present merely a general sketch of these remarkable deposits will be given, but at a future meeting a more complete paper will be presented upon the Adirondack magnetites.

THE PORT HENRY MINES.

The group of iron-ore mines in the town of Moriah, Essex county, N. Y., which embraces the largest producers in the Lake Champlain district, is reached by the railroad connecting Mineville with Port Henry. To the latter point the ore mined is carried by cars over a road of standard gauge, having three switchbacks, as the difference of elevation requires a maximum grade of 1 to 20.75 (254.5 feet per mile). But as the loaded cars are carried from the mines to the lake the objection to heavy grades is less than if the conditions were reversed. The properties of the two companies operating these mines are con tiguous, and to a stranger, the locality of some of the workings may

*This includes other mines than those mentioned in the Lake Champlain group.

appear confusing, owing to their being so close together. Several of the workings of the two companies are connected.

The mines produce two distinct varieties of ore, one being a magnetite, known commercially as "Old Bed 21" ore, carrying apatite in such quantities as to raise the phosphorus beyond the Bessemer limit, and the other a magnetite carrying a siliceous gangue, but generally low in phosphorus, known as "New Bed" ore. These designations apply to ore from various openings, the name "Old Bed" being derived from the original opening made in 1824, and now owned by Witherbees, Sherman & Co., from which a large amount of ore has been won in workings extending 1100 or 1200 feet on the slope to a vertical depth of 300 feet. The No. 21 opening of the Port Henry Iron-Ore Company (which supplies the second portion of the commercial name for the ore), with its several shafts 200 feet south of the "Old Bed" opening, which was started in 1829, is however, the largest producer, and one of the most impressive mines to view in the world. The massive pillars of ore supporting the roof (also of ore), capped with rock to within 50 feet of the surface are exposed in the great open pit to a height of 200 feet, while the chambering extends much beyond the face and to a depth of about 350 feet vertically from the surface, the distance along the slope being 700 feet.

This mine (viz. No. 21) was originally operated on the outcrop, and Prof. Maynard says of it :*

...

"In 1853, the American Mineral Company was formed under the superintendence of Prof. Emmons, the State geologist, and they took a lease of the remaining property for the purpose of extracting the phosphates from the iron-ore to be used as fertilizers. . . . It seems almost incredible, but is none the less true, that this com pany, by their contract, agreed to turn over to the owners of the property all the iron-ore after they had extracted the phosphates from it, in addition to paying them a handsome royalty. As a natural consequence the company soon became insolvent."

The amount of apatite was either much greater on the outcrop than it is now, or the operators had abounding faith in the prospects of its utilization.

Northwest of the Old Bed opening is the Miller pit of Witherbees, Sherman & Co. This opening is on nearly the same level as the Old Bed and No. 21 ore-bodies, but the slopes are not the same, the ore strikes at different elevations, but in nearly parallel directions, in each of the three veins, and a fourth ore-body apparently lies

* Journal of the British Iron and Steel Institute, vol. i., 1874, p. 121.

between the Old Bed and the Miller pit seams. An opening of the Port Henry Iron-Ore Company appears to be a continuation of the original Old Bed pit, while two openings of Witherbees, Sherman & Co. seem to be on the same ore-body as No. 21.

The possibility of these apparently distinct ore-bodies with dips varying from 30° to 70°, finally meeting in one great deposit, is claired by some who have investigated the properties.

All of the above openings produce what is known commercially as "Old Bed 21" ore, but the percentages of phosphorus vary in the different workings, none, however, being Bessemer ore. The deepest workings are now nearly 600 feet vertically below the surface. The average shipping-analyses of the ore vary from 60 to 68 per cent. of iron, and from 0.5 to 2 per cent of phosphorus.

One and a half miles northeast of the openings described are two shafts producing similar ore. These are, a slope about 1200 feet and a vertical shaft about 800 feet deep, reaching at a depth of 100 feet from the surface a large body of ore. Neither of these is worked at present, as the railroad tracks do not reach them. Other exploitations have been made in the vicinity of the mines above described, and ore from various openings was taken years ago to blast-furnaces or forges which existed in the vicinity.

The openings producing " New Bed Ore" cover a greater territorial area on account of being made upon a vein which is apparently continuous, but divided into two or three layers or scams, occasionally cut by horses, while the various deposits of "Old Bed Ore" seem to be a series of lenses lying in echelon, or nearly parallel, of varying thickness and dip.

In Volume XV. of the Tenth Census of the United States, pages 106 to 112, is found a description, accompanied by maps and partial analyses, of the ore-bodies in the vicinity of Mineville.

THE NEW BED MINES.

Mr. W. H. Tefft, Superintendent for Witherbees, Sherman & Co., states that the layers of the New Bed vein average about 8 feet in thickness, increasing at some places to 20 feet, while the maximum thickness of the Old Bed ore-bodies is yet undetermined; thus, the Miller pit ranges from 10 to 100 feet, the Old Bed pit from 20 to 125 feet, while in No. 21 the pillars rest on ore and support a roof of ore, the body being known to exceed 380 feet in thickness. The newer shafts of Witherbees, Sherman & Co., the Bonanza and Joker, vary from 30 to 150 feet in thickness. The