“When a calcareous earth, mixed up with sand, clay, and other extraneous matters, was deposited on some of the commoner molluscs of our shores, it was universally found that the mass, incoherent everywhere else, had acquired a solidity wherever it had been penetrated by the animal matter of the molluscs. Each animal, in proportion to its size, was found to retain, as in the fossiliferous spindles of the Old Red Sandstone, its coherent nodule around it. Here the animal matter gave solidity to the lime in contact with it. But in the _natural_ phenomenon of the icthyolite beds, there was yet a further point, for in these the animal matter must have possessed such _an affinity_ for the mineral, as to form, in an argillaceous compound, a centre of attraction powerful enough to draw together the lime diffused throughout the mass.” Hugh Miller concludes the above passage by saying that “it still remains for the geologic chemist to discover on what principle masses of animal matter should form the attracting nuclei of limestone nodules.” Upon which last remark, I would suggest that the principle of the “law of definite proportions,” established by Dalton, and fully borne out by all succeeding experiments in chemistry, appears to meet the case, geologically as well as chemically, in every respect. For such a law must of course obtain, whether the chemical ingredients be present in the forms of mineral, vegetable, or animal life; in fact, we have never known the law to vary. It holds for the compounded elements which we term AIR and WATER; it holds for the crystals; it holds for vascular and cellular tissues; why should it fail when the further instance of a mollusc or a zoophyte is in question? I see no reason to doubt that the blood, muscle, membrane, or adipose matter of any animal have their due respective affinities for the different substances of the mineral creation. No doubt, however, electricity, as an active cause, bears directly upon all such phenomena. I remember many years since being greatly perplexed with the _discovery_ (as I then thought it) that in certain parts of the Isle of Wight, and along the Dorsetshire coast, the rows of dark flints imbedded in the upper chalk of the cliff-ranges were all _broken_; broken _small_, so that if one were taken out of its chalk socket it crumbled in your hand. Often and often, I turned this fact over in my mind, and sought some apparent way to account for it. But I think I now see one way to account for it; and which may perhaps be judged worthy of acceptance, until a better solution is hit upon. In Dr. Hook’s experiment with that once common household implement, the “flint and steel,” he found that the _sparks_ which “fly” upon collision taking place are minute spherules of metal. And further, that this metal was now not _steel_ any longer, but iron; the fragments struck off _having lost their polarity_ in the moment of contact with the flint.