istic fossils completely identify the limestones of that tract with those of the Isle of Wight; and there can be no doubt as to the place where the formation commences, the Cypris faba being found in the clay immediately beneath the green sandstone, above the town of Hythe.

In pursuing the boundaries of the chalk around the great denudation of Kent and Sussex, the same succession of beds can be recognized in several other places.-Thus the description given by Mr. Mantell, from Mr. J. Hawkins, of the Malm rock' of Western Sussex, accords with the succession represented in Sections 1 and 2. A similar section has been communicated to me by Mr. Lyell, from the village of Shiere, between Dorking and Guilford, on the north western side of the weald district: the following being the order of the beds,-chalk, green sand with calcareous chert (firestone); blue marl (gault) of dark colour, with a few fragments of shells; and ferruginous sand (the upper beds of the green sand).-The section (fig. 1), it will be seen, corresponds essentially with that given by Mr. Webster,* * and by Mr. Phillips ("Outlines," p. 150, &c.) of the tract between Merstham and Nutfield, in Surry.-And Mr. Warburton informs me that he has traced the upper ferruginous portion of the green-sand eastward,—from Guildford through RedHill (Ryegate), River-Head, Seal, Ightham, and Wrotham Heath, to Aylesford, in the neighbourhood of Maidstone.

On the east of Godstone however, the structure of the county must still be considered as, in some degree, uncertain, for the following reasons: 1. That the firestone beds have not been traced to the west of the point above-mentioned; though their equivalent will probably be found among the harder beds at the bottom of the grey marly chalk. 2. Notwithstanding the many evidences of correspondence, the great abundance of fossils in the Folkestone marl, and their comparative scarcity throughout the Isle of Wight, is a variation of such amount as to demand the strongest evidence of geological identity. 3. The ferruginous beds at the top of the green-sand formation, have not yet been observed in the vicinity of Folkestone; while on the other hand, calcareous matter exists there in much greater proportion than in any part of the lower beds in the Isle of Wight:The fossils, however, are the same. But I have observed some appearances on the shore between Sandgate and Folkestone,

* Geol. Trans. vol. v. p. 353.

+ On the opposite coast of France, the Folkestone marl occurs beneath the chalk without the intervention of the fire stone, at least in a prominent form. I have traced it with most of the characteristic shells of Folkestone, all round the denudation of the lower Boulonnois, from the foot of Blancnez, through Boursin, Colemberq, Lottinghen, &c. to the vicinity of Samer; and have found in several places beneath it traces of green sand. In Mr. Smith's maps of Kent and Surry, the gault is continued, without interruption, from the west of Dorking to the coast.

which seemed to render this part of the series deserving of further examination.

Coast of Dorsetshire.

V. The progressive condensation, and thinning out of the strata towards the west,* is such, that the space occupied by the beds between the chalk and the lowest visible part of the Hastings sands,—which is in Sussex (from Folkestone to Winchelsea, fig. 1),—more than twenty miles in extent,-is reduced successively; in the Isle of Wight (between Rocken-End and Southmore), to about eight miles ;-at Swanage Bay, fig. 3, to less. than one mile and a half;- at Worbarrow, fig. 5, to less than three-quarters of a mile; and finally at Durdle Cove, fig. 6, where these beds appear, for the last time, on the coast, to less than a furlong:-the horizontal distance in a direct line between Folkestone and Durdle Cove, the extreme points of this series, being about 170 miles. This convergence, it is true, appears much greater than it actually is, in consequence of the high inclination of the strata on the coast to the west of Purbeck, where at last they become very nearly vertical; but the condensation is really sufficient to make it more extraordinary that so many members of the series have been retained, than that some beds should be wanting.

At Worbarrow, and in the coves to the west of that place, I could not detect any trace of the weald clay, between the sands below the gault; the sections (fig. 5 and 6) affording only one continuous series of sandy beds, from the gault to the commencement of the Purbeck strata. But at Swanage (fig. 4 and 5) I was more successful, having found there distinctly the equivalent of the weald clay;-beds of bluish slaty clay containing the cypris faba, and other shells of the same species with those of the Isle of Wight; and limestone in thin strata, composed of bivalves, with small paludinæ, and of oysters, and in some cases encrusted with obscurely fibrous carbonate oflime. Beds, also composed of mottled greenish-grey sand and grey clay, like those of Sandown and Cowleaze chines, occur in this part of the section.-— But the sands interposed between the weald clay and the Gault are not in themselves distinguishable, at Swanage Bay, from the inferior (Hastings) beds; the green particles being wanting, and the sands differing only in colour, fineness of grain, and a variable admixture of clay. There are among them some remarkable courses of a very fine grained calcareous grit used by the Swanage quarry-men for sharpening their tools: but I have not

* See Webster, Letters, p. 194, and Plates.

The difference as to the impression produced on the observer, by beds of the same thickness when nearly horizontal, and when highly inclined,-which arises from our habit of estimating heights and horizontal space by very different scales, deserves the attention of those who are not much accustomed to geological observation. Thus a bed, or group, 200 feet thick, if horizontal, forms a very striking cliff; but as part of an highly inclined series, it may be passed by with comparatively little notice.

yet had an opportunity of comparing the specimens, with those of the Whetstone quarries at Blackdown, in Devonshire, which are in the green sand.

Fig. 3, is a section southwards from the chalk near this place to the town of Swanage, but reversed, for the purpose of showing its correspondence with that of the Isle of Wight at Compton Bay and I have also copied a portion of Mr. Webster's accurate view of the coast, for the purpose of pointing out more precisely the situation of the clays.*-In this sketch (åg. 4) the spectator is supposed to be placed upon the firestone where that bed first rises from under the chalk, and to look along the shore towards Swanage. Masses of fallen chalk are seen between this place and the commencement of the Hastings sands-but these are easily accounted for,-being in fact an undercliff, produced exactly in the same manner as in the Isle of Wight-and the firestone and gault rise and hold their place with as much regularity as I have any where else remarked. The section of the Hastings sands, in Swanage Bay, comprehends the whole of the formation, and gives one of the most distinct views of it that can be obtained in England. corresponds completely, at the upper part, with the beds which are visible in the Isle of Wight, and at Hastings.

It

V1. Very little is yet known of the strata which form the subject of this paper, in the interior of England; but an attentive perusal of Mr. Conybeare's descriptions will show that some of the obscurities connected with them, may be resolved by referring to the order in which the beds are exhibited in the Isle of Wight. I am in fact unwilling to abandon the expectation of finding in this part of the series the same steadiness of arrangement, that is known to exist in other portions of it the reasoning which implies, that less of regularity is to be expected in a suite of sands and clays than elsewhere, having always appeared to me to be insufficient. It is the fact alone, established by extensive observation, that could have rendered credible the identity and constancy of succession of any portion of the strata; and we really know so very little of the mode in which they have been formed, that our estimate of the comparative probability of regularity in one description of beds, of sand, or clay, or limestone, more than another, is matter of the very slightest conjecture.

* The place where all the beds above described occur is called Punfield. The examination of it is rendered difficult by the position of the strata, which retire obliquely inland, and at the same time, when seen from the shore, rise towards the eye; so that the weald clay lies behind the upper beds of the Hastings sand, in a nook, where it is so much obscured by the fall of the incumbent substances, that without the assistance of quarry-men I could not have obtained a view of the beds in situ.

ARTICLE XII.

SCIENTIFIC NOTICES.

CHEMISTRY.

1. Juice of Elder Berries as a Test.

THE juice of the elder berries seems to possess important properties as a delicate reagent. The following process was employed :

Take any quantity of the ripe berries, picked clean from the stalks, and after having bruised them, press the juice into a clean well-tinned vessel. Add a fourth part of its weight of alcohol, and evaporate the mixture to one-half. Remove it from the fire for ten or twelve minutes, and add as much alcohol as you have of concentrated juice. A copious precipitation of the parenchymatous and gummy parts will take place, which will permit the liquor to be strained with ease through a fine cotton cloth.

The filtered liquor is now fit for use. It consists of the saccharine and colouring principles of the berries, in solution with alcohol and water. It is of a beautiful violet colour. In order to ascertain its utility as a test of acids and alkalies, the following experiments were made:

To one pint of rain water a single drop of the tincture of elder berries was added. The blue colour was too pale to be perceived; but the addition of a single drop of sulphuric acid produced a decided red colour.

To the liquor employed in the last experiment, a minute quantity of alkali was added, when it immediately changed to a bright lively green. If a quantity barely sufficient to neutralize the acid be employed, the original blue or violet colour is restored; hence this test possesses all the delicacy of the tincture of litmus, or blue cabbage, and has this additional valuable property of keeping unaltered, during the hottest season of the year. The species tried as above was the Sambucus canadensis; the juice of the common elder berry (Sambucus nigra) will probably answer as well.-(Annals of the Lyceum of Nat. Hist. of New York.)

2. Volatility of the Salts of some of the Vegetable Alkalies,

Ferrari states that all the salts of Strychnia, when dissolved in water, are volatile in temperatures below that of boiling water. The volatilization is most considerable when the solution is concentrated, and when it contains an excess of acid. The salts which he examined were the sulphate, muriate, nitrate, and acetate. He remarked also that the muriate of chinin is so volatile that the steam which rises from its aqueous solution in a

state of ebullition, has a decidedly bitter taste. The volatility of the sulphate of chinin had been previously taken notice of by Callaud.-(Giornale di Fisica, &c. vi. 457.)

3. Existence of Manna in the Leaves of Celery.

Dr. A. Vogel finds the following substances in the leaves of this plant (Apium graveolens).

1. A colourless volatile oil, in which resides the peculiar odour of the plant.

2. A thick fatty oil, partly combined with chlorophyle.* 3. A distinct trace of sulphur.

4. A tremulous jelly, or bassorine, which acquires a gelatinous consistency, by the action of weak acids or of water.

5. A brown extractive matter, soluble in alcohol, and precipitated by solutions of tin and lead.

6. Gum.

7. Manna.

8. A very considerable quantity of nitrate of potash. 9. Muriate of potash.

The manna may be extracted by boiling the filtered juice of the leaves in order to precipitate the chlorophyle and vegetable albumen, and evaporating the liquid thus purified, to the consistency of honey it separates on cooling in greyish white acicular crystals. But the most accurate procedure is to digest this thick liquid for a few minutes in alcohol, and to filter the solution while boiling hot. After some hours it concretes into a soft white coloured mass, resembling a cauliflower: this may be rendered considerably purer by squeezing out the alcoholic liquid, redissolving the solid portion, and crystallizing a second time.

Thus obtained, it possesses all the properties of manna purified by solution in alcohol. Like this, it has a sweet taste, is very soluble both in cold and hot water, dissolves but sparingly in cold, and to a large amount in hot alcohol, and on cooling separates from the solution in the form of a soft white mass, resembling a mushroom. The solution also is quite incapable of the spirituous fermentation.

The fresh leaves of celery yield rather more than one per cent. of manna, purified by repeated crystallization.

He could not succeed in detecting a trace of manna in the leaves of common parsley (Apium Petroselinum), or of the common leek (Allium porrum).

This is the first well authenticated instance of manna occurring in the leaves of an European plant.-(Schweigger and Meinecke's Jahrbuch der Chemie und Physik, vii. 365.)

* This is the name which Pelletier and Caventou have applied to the green colouring matter of leaves, and which would appear from their experiments to be a peculiar vegetable principle. (See Journal de Pharmacie, iii. 486.)

New Series, VOL. VIII.

2 c