In the Popular Science Monthly of January 1897, a short article by J.T. Donald, entitled "A Curious Canadian Iron Mine," describes the same thing going on at the present time in Lac a la Tortue, a small body of water in the center of a tract of swamp land, which produces the vegetation necessary to supply the acid required for a base of operation. Of the manner of deposition he says: "The solution of iron in vegetable acid (in which the iron is in what the chemist calls the form of a protosalt) is oxidized by the action of the air on the surface of the lake into a persalt, which is insoluble, and appears on the surface in patches that display the peculiar iridescence characteristic of petroleum floating on water. Indeed, not infrequently these films of peroxide of iron are incorrectly attributed to petroleum. These films become heavy by addition of new particles; they sink through the water, and in this manner, in time, a large amount of iron ore is deposited on the lake bottom. It must not be supposed that the ore is deposited as a fine mud or sediment. On the contrary, in this lake ore, as it is called, we have an excellent illustration of what is called concretionary action--that is, the tendency of matter when in a fine state of division to aggregate its particles into masses about some central nucleus, which may be a fragment of sunken wood, a grain of sand, or indeed a pre-formed small mass of itself." It is claimed for this water ore, which is gathered like oysters, that mixed with bog ore and magnetic iron, and smelted with charcoal, the result as obtained is strong, durable and high priced. The curiously elastic quarter of a mile finally yielded to persistent toil, and the cave was reached. The entrance is sufficiently broad to give a good first impression, and is under a heavy ledge of limestone which breaks the slope of the hill and is artistically decorated with a choice collection of foliage, among which is a coral honeysuckle; the fragrant variety grows everywhere. Under the ledge is a narrow vestibule, out of the north end of which is a passage about twenty-four inches in width, between perpendicular walls, and as steeply inclined as the average dwelling-house stairway but without any assisting depressions to serve as steps. Mr. Irwin cut a grape vine, and making one end secure at the entrance, provided a hand rail, by the aid of which I was able to easily descend the stepless way and afterwards remount.