Number XXVI.

This is a whetstone, which as Mr. Anthony Shane apothecary, who was born very near the lake, and is now alive, relates, he made by put-ting a piece of holly in the water of the lake near his father's houfe, and fixing it, fo as to withstand the motion of the water, and marking the place fo as to diftinguifh it, he went to Scotland to purfue his ftudies, and seven years after, took up a ftone instead of holly,. the metamorphofis having been made in that time. This account he gave under his hand writing. The shore thereabouts is altogether loofe fand,, and two rivers discharge themfelves into the lake very near that place.

Number XXVII.

This is not ground into a whetstone, not being of a proper shape but it is claffed here, upon account of the evident tearing of the ligneous fibres tranfverfly, and very irregularly, before the metamorphofis into ftone, which it now is become almost intirely. For when timber falls. promifcuously in a heap, fome pieces will lie parallel, and fome tranfverfe, and fome almost upright, and in all manner of directions.

Number XXVIII. A. B.

Two fragments of one mafs, in which the crystalline matter appears in different forms. In A, in many fmall fiffures, according to the fibrous directions of the wood now become ftone, but in one part, where they are broken tranfverfly, it appears intermixt with black, fo, as to exhibit a grey colour. N. B. This cryftalline appearance is never obferved difperfed through the woody part of the maffes, although a fmall. flice of wood has been obferved incompaffed with a cluster of crystals,, lying upon the inner surface of a cleft of a large mafs (a),

Number

(a) This leads to a proof, that the matter of thefe ftones is for the most part crystal...

Number XL.

This is a fpecimen of wood alone, which tho' found in the bed of mixt matter, hereafter described in the hiftorical lecture, has undergone no change in refpect to petrification. It is what workmen call burry, or cross grained, yet it admits a plain, and is thereby reduced to a smoothnefs; there is another mafs of fimilar matter in the fame clafs, being altogether wood, and cleaves eafily according to a straight grain; both thefe caufe a pleasant smell in burning.

Number LF.

Shews the crystalline matter, concreted with a mass of small crystals, at the infide of a mafs of mixt matter, wood and ftone. (b.) A is the 'external furface, being firm ftone, B is part of the interior mafs, being almost an equal mixture of wood and ftone, of a dark brown colour, inclining to black, like many others of the fame kind; the part C is entirely a cluster of small transparent coloured crystals.

Number LII.

This is a curious congeries of mixt matter, extremely rough and irregular in the surface, having the white colour peculiar to ftones long exposed on the fhore, but very much dirtied by a kind of froth, obfervable in fome, like barm in colour, which is dried upon the greatest part of the furface. The mafs being broken, exposes to view the part A an extreme hard black ftone, with a few ftreaks of crystalline matter; aswell as fome glistening matter equally fcattered through the black: In the neighbourhood of it, is a cavity very irregular, being lined with a rough concretion of matter, partly fand and partly cryftalline matter, in tubercles, wherein the crystalline matter gliftens; in the midft running the length: of the cavity, is a thin prominent flice of mixt matter, the external part of which is fand concreted into final tubercles, and the internaf

part iss

(b) A and B are written on paper and pafted on the fpecimen, as well as other letters»

ufed in thefe defcriptions.

is a line of fhining crystalline matter half way the length, which dividing, exhibits to view, two oppofite rows of very fmall crystals: So that where a crack in the original wood was very fmall, the cryftalline matter appears like a white line; where it is larger, it has fpace to form crystals of a regular figure; as appears more evidently at B. At C in the crystalline matter may be seen paffing tranfverfly, or cross the fibres. N. B. Thefe rough concretions are never found, except in ftones that appear to have been long expofed to the water, and turned out of their native bed. For the fpecimens found deep under ground, although they afford beautiful congeries of crystals, have not any of these rough concretions. The rough part in the neighbourhood of A above described, had a free communication with the water when it was found.

Number LIIL

A fmall fpecimen fhewing the cryftalline matter running transversly, alfo a cavity with regular formed crystals.

Number C.

A ftone burnt in a culinary fire, which at firft emitted a faint flame, but although frequently burnt afterwards, emitted no more flame, but grew red hot, and when cooled had always the fame vifible appearance, -which it has now, being white in the furface, and black inwardly, intirely refembling charcoal. N. B. upon breaking this ftone, fo as to expofe the internal parts, to the immediate influence of the fire, the parts immediately expofed would become white, for this was tried in other inftances.

Number CI. A.B.

The fpecimen A is burnt in a culinary fire, and fhews a near refemblance to B, which was not burnt except by the folar heat upon the hore; in both thefe may be feen a rim of white matter, incompafling a feemingly black charcoal within.

Number

Number CII.

A burnt fpecimen wherein fome crystalline matter, ftill retains a gliftening appearance, tho' not formed into cryftals, but difperft irregularly through the black part of the mass.

Number CIII. A. B. C. D. E..

A mafs found upon the fhores, which by rolling as the water moved it, is worn into a form fomething orbicular. Its furface is white, and where a crack, almoft invifible, allowed moft free accefs to air and folar influence, the oppofite fides are white, as appears by breaking it in that part; but the rest of that mafs internally is almost black. B is a small fpecimen exhibiting the fame appearances, and alfo, the cryftalline matter irregularly difperft and gliftening. C is a fpecimen wherein all these things are more difcernible; and D is a fpecimen fingularly remarkable in this refpect: It is a small fragment of a large mafs, which being. placed in building as the upper corner ftone of a fmall country houfe near the lake, it is almoft intirely become white, having probably been expofed to the weather in that fituation above thirty years. E is a fpecimen which has been several times in a culinary fire, it has a good deal of iron ore, which being scraped, where it appears in red ftriæ, readily leaps to the magnet.

N. B. Some of the fpecimens of wood petrifyed, fo as to be totally converted into ftone, were put into the fire, and after becoming red hot, were taken out and weighed in water, and weighed again after imbibing the fluid: from which it appeared, there were fome combustible fibres of wood, which were confumed by the fire, and thereby gave admiffion to the water, except in one fpecimen of the white kind, which being totally converted, fuffered no alteration; for it is elsewhere remarked in thefe lectures, that the perfect ftones of this kind bear a very intense heat without fufion or calcination.

Number

A vitrified crucible and burnt ftone, defcribed in the following experiments.

Experiments made for the Rev. Mr. BARTON.

this

I powdered finely two drachms weight of the ftony matter, and the fame weight of the woody matter; and put each into two ounces of highly rectifyed fpirits of wine -after they had macerated for a week, found that the woody matter had afforded the fpirit a very strong tincture, of as high a colour as common tincture of myrrh, tincture had a very aromatick fmell and taste, and upon putting a little of it into a certain quantity of water, the water became of a milky colour,in this mixture I found the aromatick fmell and taste, more manifeft than in the tincture alone.

At the fame time, the ftony matter had scarce changed the colour of the fpirits, nor could I perceive any difference in tafte, or smell, between that and plain fpirits: And upon putting the fame quantity of water as of the tincture in a vial; I found that mixture did not differ in taste, fmell or colour, from a mixture of common rectified fpirits and water., I put the ftones you defired to have calcined into a crucible, and gave it the highest heat that an air furnace would admit of, for the fpace of eight hours; in which time part of the crucible, was vitrified, yet I could not perceive that the ftones had fuffered the least change.

ROBERT DAVIES.

The world may expect useful operations in Chirurgery, from the diligence and ingenuity of this young man, whofe ftudies are in that art.

N. B. Thefe ftones were petrifications of the lake, which had been burnt before in a culinary fire feveral times, and are to be seen in the collection.