ty of

the water, is to trees. An inditered a cavity by Hance of food by within such cavibulk as to render arrow aperture at s very likely to be only people whose

in the interior of and lizards, that quarry, or in

in a

of coal at the botFect to shew that ock; no examinaiscovered by the d, and then it is g every fragment as this ever been crevice by which which it was exlmost impossible . In the case of -ne quarries, .repWe have a no

and in a chalk pit, the case also of own the well or atural retreat in miner dislodging on had not been nimal was coeval

ich I know not ve been said to o which, on carediscovered, and closed up with probable

Toads enclosed in Stone and Wood.

31

surface had been closed up by stalactitic incrustation after the animal had become too large to make its escape. A similar explanation may be offered of the much more probable case of a live toad being entirely surrounded with solid wood. In each case the animal would have continued to increase in bulk so long as the smallest aperture remained by which air and insects could find admission; it would probably become torpid as soon as this aperture was entirely closed by the accumulation of stalactite or the growth of wood; but it still remains to be ascertained how long this state of torpor may continue under total exclusion from food, and from external air: and although the experiments above recorded shew that life did not extend two years in the case of any one of the individuals which formed the subjects of them, yet, for reasons which have been specified, they are not decisive to shew that a state of torpor, or suspended animation, may not be endured for a much longer time by toads that are healthy and well fed up, to the moment when they are finally cut off from food, and from all direct access to atmospheric air.

The common experiment of burying a toad in a flower-pot covered with a tile, is of no value, unless the cover be carefully luted to the pot, and the hole at the bottom of the pot also closed, so as to exclude all possible access of air, earthworms and insects. I have heard of two or three experiments of this kind, in which these precautions have not been taken, and in which, at the end of a year, the toads have been found alive and well.

Besides the toads enclosed in stone and wood, four others were placed each in a small basin of plaster of Paris, four inches deep and five inches in diameter, having a cover of the same material carefully luted round with clay; these were buried at the same time and in the same place with the blocks of stone, and on being examined at the same time with them in December, 1826, two of the toads were dead, the other two alive, but much. emaciated. We can only collect from this experiment, that a thin plate of plaster of Paris is permeable to air in a sufficient degree to maintain the life of a toad for thirteen months.

In the 19th Vol. No. 1, p. 167, of Silliman's American Journal of Science and Arts, David Thomas, Esq. has published some

observations on frogs and toads in stone and solid carth onu

32 On the Vitality of Toads enclosed in Stone and W merating several authentic and well attested cases; the ever, amount to no more than a repetition of the facts stated and admitted to be true, viz. that torpid reptiles cavities of stone, and at the depth of many feet in soil ar but, they state not any thing to disprove the possibi small aperture, by which these cavities may have had c cation with the external surface, and insects have been a The attention of the discoverer is always directed mo toad than to the minutiae of the state of the cavity in was contained.

In the Literary Gazette of March 12. 1831, p. 16 is a very interesting account of the habits of a tame ma that was domesticated and carefully observed during alr years by Mr F. C. Husenbeth. During two winter November to March, he ate no food, though he did not torpid, but grew thin and moved much less than at othe During the winter of 1828, he gradually lost his appe gradually recovered it. He was well fed during two su and after the end of the second winter, on the 29th of 1829, he was found dead. His death was apparently by an unusually long continuance of severe weather seemed to exhaust him before his natural appetite re He could not have died from starvation, for the day be death he refused a lively fly.

Dr Townson also, in his tracts on Natural History, (1 1799), records a series of observations which he made o frogs, and also on some toads; these were directed to the very absorbent power of the skin of these reptile show that they take in and reject liquids, through the alone, by a rapid process of absorption and evaporation,absorbing sometimes in half an hour as much as half weight, and in a few hours the whole of its own weight ter, and nearly as rapidly giving it off when placed in an tion that is warm and removed from moisture. Dr T. co that as the frog tribe never drink water, this fluid must b plied by means of absorption through the skin. Both fro toads have a large bladder, which is often found full of "whatever this fluid may be, (he says), it is as pure as d

water and equally tostoloss. this I accout as well of that

e and Wood.
ses; these, how-

he facts so often

reptiles occur in En soil and earth; e possibility of a ve had communi

e been admitted. ected more to the cavity in which it

1, p. 169, there

tame male toad, uring almost two Fo winters, from did not become n at other times. his appetite and ng two summers, 29th of March, pparently caused weather, which petite returned. e day before his

Listory, (London

e made on tame directed chiefly ese reptiles, and ough their skin oration,-a frog as half its own n weight of waced in any posi Dr T. contends id must be supBoth frogs and d full of water;

pure as distilled

the

( 33 )

On the Chemical Constitution of Harmotome, or Cross-stone.
By ARTHUR CONNELL, Esq., F.R.S.E. Communicated by
the Author *.

IN
In examining some specimens of harmotome from Strontian, I
observed some crystals which appeared to present a very dif-
ferent aspect from the ordinary harmotome with which they
were associated. The usual crystals of this mineral from the
above locality are well known to be of considerable size, and to
exhibit the form of a rectangular prism, Plate I. Fig. 1, termina-
ted by a pyramid, the faces of which are set on the lateral edges of
the prism, two opposite edges of the pyramid being also replaced
by planes. On the other hand, the crystals to which I have re-
ferred were a great deal smaller in size, usually not exceeding
one-tenth of an inch in length, and of greater transparency;
and they presented the apparently very dissimilar form of a
rhombic prism, Fig. 3, of considerable acuteness, having the
acute angle more or less truncated by the face A, and termi-
nated by a pyramid C, the faces of which were set on the late-
ral planes of the prism, and its apex truncated. They were
spread over the surface of calcareous spar in considerable num-
bers, and were usually attached to the matrix by one of the ex--
tremities D' D. Farther consideration, however, showed that
this latter form was in reality merely a modification, although
undoubtedly a very considerable one, of the old form, and
arose principally from the vertical contraction of the crystal,
Fig. 1, and its horizontal elongation in the direction of the faces
BB', the inclination of the several faces to one another remain-
ing always the same; as will be evident by comparing Figures
1, 2, and 3, Fig. 2 representing another form of the crystal, which
may be regarded as intermediate between Figs. 1 and 3, and the
whole three being placed in parallel position, with their corres-
ponding faces marked by the same letters. In some rare in-
stances, the pyramids CC, and the face A, Fig. 3, almost en-
tirely disappear, so that the crystal appears nearly as a simple
rhombic prism; and in others equally rare, the face D almost
disappears, so as to leave the pyramid nearly without truncation.

{ * Read to the Royal Society of Edinburgh, 2d April 1832.

On the Chemical Constitution of Harmotome.

A few minor modifications of both forms also occur, wh

I was farther confirmed in these views of the conne tween the two forms, by the opportunity which the of Mr Allan afforded me of consulting the interesting o of his collection, drawn up by Mr Haidinger, in which a series of figures of harmotome crystals, presenting, as I could judge, a transition of the one form into t with some of those lesser modifications to which I have

As the angle of the faces B, replacing the opposite the pyramid in Fig. 1, has been stated by Mr Phillips as this will of course become the measure of the rhombi Fig. 3, if the foregoing views of the relation between forms s are correct.

Before the connexion of the two forms Figs. 1 and 3 curred to me, which was not until I had observed a c the form Fig. 2, I commenced an analysis of a portion crystals of the rhombic form, Fig. 3, under the idea th might present some modification of the usual constit this mineral; and although they proved to be merely a harmotome, yet the analysis seems to throw some litt tional light on the connexion between the barytic and rieties of the mineral. The steps of the analysis were as

(a.) 7.37 grains of the crystals in coarse powder los nition, 1.1 grain, equivalent to a loss of 14.925 per cent.

(b.) 16.07 grains of the crystals which had been pr treated with acidulated water, to remove all adhering ca spar, were reduced to impalpable powder, and then left f or four days in contact with muriatic acid, a moderate he occasionally applied. The mass did not gelatinize; but afterwards appear, the action was quite sufficient for the of analysis. The whole was evaporated to dryness. muriatic acid was then poured over it, and left for som when water was added, and heat applied. The silica w separated by filtration. After ignition, it weighed 7.55 It dissolved in boiling caustic potash ley, except a res .47, which was resolved by fusion with carbonated alkal

(c.) The liquid from which the silica had been separated was precipitated by ammonia. The precipitate, after being collected on a filter and duly washed, was dried and ignited. It then weighed 2.53 grains. It was dissolved in muriatic acid, and left a residue of .03 of silica. The muriatic solution was then boiled with caustic potash. What remained undissolved by the potash was collected and washed, and then treated with muriatic acid. A residue of .02 of silica was left by the acid. The muriatic solution was boiled with nitric acid, neutralized by ammonia, and precipitated by benzoate of ammonia. The benzoate of iron was burned with a little nitric acid, and the peroxide of iron thus got weighed .03. The residual fluid boiled with carbonate of potash gave an insignificant white precipitate, too small to weigh or examine. There thus remained of alumina, dissolved by the caustic potash, 2.45 grains.

(d) The liquid which had been precipitated by ammonia, together with the washings of the precipitate concentrated by evaporation, was heated, and carbonate of ammonia added to it whilst hot. The precipitate which fell, weighed, after being washed and ignited, 4.36 grains. It was dissolved in dilute muriatic acid, and left .01 of silica. The solution by evaporation afforded tabular crystals of muriate of baryta.

(e.) The crystals of muriate of baryta were washed with alcohol. The alcohol was separated, mixed with water, and evaporated to dryness, when a little deliquescent matter was left. This was re-dissolved in water, and the solution precipitated by oxalate of ammonia. The precipitate by calcination afforded .03 of carbonate of lime, equivalent to .0168 of lime. By subtracting from the amount of the precipitate by carbonate of ammonia, the substances afterwards separated from it, we get 4.32 of carbonate of baryta, equivalent to 3.3517 of baryta.

(ƒ) The liquid which had been precipitated by carbonate of ammonia, in (d) was evaporated to dryness, and the ammoniacal salt driven off by heat. The residue, after ignition, weighed .5. Dissolved in water it left .02 of silica, giving .48 for the soluble residue. The solution by evaporation gave cubical crystals. Re-dissolved, the liquid was plentifully precipitated by muriate

c 2