STONES, in natural history, are defined to be essentially compound fossils, not inflammable, nor soluble in water or oil, nor at all ductile: found in continued strata, or beds, of great extent: formed either of a congeries of small particles, in some degree resembling sand, and lodged in a smoother cementitious matter; or else of this cementitious matter, and the gritt or sand-like particles, running together into one smooth
smooth mass; or, finally, of granules cohering by contact, without any cementitious matter among them; or composed of crystal or spar, usually debased by earth, and often mixed with talc and other extraneous particles.
Of this class of fossils there are three orders; and under these, eight genera.
The first order comprehends all the coarse, harsh, and rough stones, of a lax texture, and composed of a visible gritt, resembling sand in form, and usually immersed in a cementitious matter, and of little natural brightness; scarce capable of any polish, and naturally mouldering away in form of powder from the tools of the workmen. The genera of this order are two, viz. the amnochista and psaduria; the former of which constitute our grey and rough slates; and the latter comprehends most of the stones used in building, particularly Portland stone.
The second order consists of stones moderately fine, of a more compact and even texture, scarce distinguishable construction, and affording no sand-like particles to the view; of some natural brightness, capable of a tolerable polish, and flying off from the tools of the workmen in form of small chips. Under this order are comprehended the symplexia and Regania.
The third order consists of stones of a very fine substance and elegant structure, naturally of a great brightness, and capable of an elegant polish; composed of granules of various shapes and sizes, but usually flatish, sometimes more sometimes less distinct; and, in some species, running together into uniform masses, but never lodged in any cementitious substance. Of this order are the marbles, alabasters, porphyries, and granites.
For the Origin and Formation of Stones, M. Tournefort, on his return from the east in the year 1702, proposed to the Royal Academy a new theory.—On a curious survey of the famous labyrinth of Crete, he observed, that several people had engraven their names in the living rock whereof its walls are formed; and, what was very extraordinary, the letters whereof they consisted, instead of being hollow, as they must have been at first (being all cut with knife-points), were prominent, and stood out from the surface of the rock like so many basso-relievo's. This is a phenomenon no otherwise accountable for than by supposing the cavities of the letters filled insensibly with a matter issuing from out of the substance of the rock, and which even issued in greater abundance than was necessary for filling the cavity. Thus is the wound made by the knife healed up, much as the fracture of a broken bone is consolidated by a callus formed of the extravasated nutritious juice which rises above the surface of the bone; and this resemblance is the more just, as the matter of the letters was found whitish, and the rock itself greyish. Something very like it is observed in the barks of trees, wherein letters have been cut with the knife; so that the poet had reason to say, that the characters grew as the trees themselves grew: Crescent illa, crescentis amores.—M. Tournefort supports his opinion by similar causes apparently formed in several other stones, which had reunited after by accident they had been broken.—From these observations it follows, that there are stones which grow in the quarries, and of consequence that are fed; that
the same juice which nourishes them serves to rejoin their parts when broken, just as in the bones of animals and the branches of trees when kept up by bandages; and in a word, that they vegetate.
M. Tournefort examines several kinds of stones, and finds them under the same necessity of feed. The immense quantity of flints wherewith the Crau of Arles is covered, he uses as an argument in behalf of this theory. The country there, for 20 miles round, is full of roundish flints, which are still found in equal abundance to whatever depth you dig. M. Peirese, who first proposed the generation of stones by means of feeds, (though he took the word feed in a very different sense from M. Tournefort), first brought this extraordinary campagne as a proof thereof. In effect, how could so many similar flints be formed? There is no saying they are coeval with the world, without asserting at the same time that all the stones in the earth were produced at once; which were to go directly contrary to the observations above-mentioned.
Among the feeds of stones, M. Tournefort observes, there are some which do not only grow soft by the juices of the earth, but even become liquid. These, then, if they penetrate the pores of certain bodies, grow hard, petrify, and assume the figure or impression of the body: thus what we call pectinites, conchites, mytilites, ostracites, nautilites, echinites, &c. are real stones, the liquid feeds whereof have insinuated into the cavities of the shells called pecten, concha, mytilus, ostrea, nautilus, echinus. On the contrary, if those liquid feeds fall on flints, on shells, sand, &c. they inclose those several bodies, and fixing between them, form a kind of cement, which yet grows like other stones. It is highly probable, he thinks, that such rocks as are only an assemblage of masticated flints, have been formed by a number of these liquid feeds, in like manner as the quarries full of shells; unless the rocks have enveloped these bodies in their growth. He adds, that there are feeds of real stones inclosed in the spawn of certain shell-fish, as well as that hard solid matter destined to the forming their shells.
There is a particular kind of shell-fish called pholas, which is never found anywhere but in the cavities of flints, which are always found exactly fitted to receive them. Now it is highly improbable the fish should come and dig such a niche to spawn in; it is much more likely the stones they are found inclosed in were at first soft, and that the matter they are formed of was originally found in the spawn, in like manner as the matter which forms the egg-shell is really found in the feed thereof. See PHOLAS.
From the whole, he concludes, that the feed of stones, and even of metals, is a kind of dust which probably falls from them while they are alive, i. e. while they continue to vegetate as above. This dust may be compared to the feeds of several plants, as those of ferns, mosses, truffles, &c. which no microscope ever yet discovered, though their existence is not at all to be doubted.
M. Geoffroy accounts for the origin and formation of stones in a different manner. He lays it down as a principle, that all stones without exception have been fluid; or at least a soft paste, now dried and hardened; witness the stones wherein are found foreign bodies; witness also figured stones, &c.
On this principle he examines the formation of the different kinds of stones; and shows, that the earth alone suffices for the same, independent of all salts, sulphure, &c. The metallic particles contained in flints give them their colour, but these are only accidents; for proof of which, he instances the sapphires and emeralds of Auvergne, which lose all their colour by a moderate fire consuming their metallic parts, but without any damage to their transparency, they being hereby rendered mere crystals. M. Geoffroy conceives two kinds of primitive particles in the earth. Those of the first kind are exceedingly fine thin lamellæ, equal to each other, or nearly so. Now, when these meet together, from any cause whatever, in a sufficient quantity, the regularity and equality of their figures determine them to range themselves equally and regularly; and thus to form a homogeneous compound, which is very hard from the immediate contact of the parts, and very transparent by reason of their regular disposition, which leaves a free passage to the rays of light every way: and this is crystal. The parts of the second kind have all sorts of irregular figures, and must accordingly form assemblages that are much opaker and less hard. Now crystal is formed wholly of parts of the first kind, and all other stones of a mixture of the two kinds of parts put together; this mixture is absolutely necessary in order to unite and bind together the parts of the second kind, and give them a hardness and consistence, without which they would only make a sand or dust. Water now appears to be the fittest vehicle to carry the parts of the first kind. This is seen from several petrifying springs, which incrustate the pipes through which their waters are conveyed, or even solid bodies laid in them for some time. The water does not dissolve those earthy parts; it only keeps them in fusion, as it does the juices wherewith plants are fed. This water, thus charged with earthy particles of the first kind. M. Geoffroy calls the stony or crystalline juices, whereof those bodies are primarily formed.
STONES are of various kinds, with regard to the places they are produced in: the most ordinary are under ground; others in the bodies of men and other animals; others seem to be generated by the sea, as pumice, &c.; and others the effect of a petrifying virtue in certain waters. See PETRIFICATION, &c.
Artificial STONE. See STUCCO.
STONE in the Bladder. See MEDICINE, no 486. and SURGERY.
STONE also denotes a certain quantity or weight of some commodities. A stone of beef at London is 8 pounds; in Hertfordshire, 12 pounds; and in Scotland, 16 pounds.