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splendid discovery. My object in this communication is, to convince those who doubt the existence of organic remains in agates from the Sone river, or elsewhere‘. I therefore beg leave to refer them to the following passages in Dr. Uns’s Dictionary of Chemistry, published about

fifteen years ago, which, in my humble opinion, establishes my point.

“ These curious appearances (meaning the organic remains of plants) were ascribed to deposites of iron or manganese ; but more lately they have been thought to arise from mineralized plants of the cryptogamous class.” And again, “ Dr. MCCULLOCH has recently detected what Daunmrron merely conjectured, in mocha stone and moss agates, aquatic confervae, unaltered both in colour and form, and also coated with iron oxide. Mosses and lichens have also been observed along with chlorite, in vegetatious. An onyx agate, set in a ring, belonging to the Earl of Powls, contains the chrysalis of a moth.” I am also of opinion, that the arhorescent appearance termed Dendrites in our magnesian limestone, and flag sand-stone, are the remains of mosses and lichens. I have several times tested the substance, but could only detect carbon, which certainly indicates their vegetable origin. I doubt not when they are efiectually examined, but they will turn out to be the remains of vegetation.”

The beautiful specimens from the sandstone of Chunar afi'ord an excellent opportunity to those who may Wish to set the matter at rest, and I must here remark, that you, as Secretary of the Asiatic Society of Calcutta, might easily accomplish the desired examination.

I also have another reason for troubling you with this communication. If the appearances in the agates are not the remains qf plants, I have in that case asserted a falsehood in my advertisement, published in No. 39 of your Journal. However, with such authorities as the above mentioned, I need not fear again to assert, that the appearances in my agates are the real organic remains of aqueous plants, in a state of preservation not exceeded by any previous discovery, and altogether (as a collection), unique.

Dr. U1zs’s Geology affords further proofs to strengthen my original opinion, that the appearances in my agates are truly the remains of plants; thepassage runs thus:

“ If any further evidence of the aqueous origin of chalcedonies and agates were wanted, it has been alforded by Dr. MCCULLOCH in an ingenious paper on the vegetable remains preserved in these siliceous minerals, published in the 3rd volume of the Transactions of the Geological Society. It is there shown that the mode in which the delicate vegetables thus become involved is perfectly simple, and consist

ent with the production of chalcedony. But we must distinguish their real causes, from pseudo specimens of black arborizations, produced by the oxides of manganese

_ and iron, or by chlorite.

“ When real confervae are present, the vegetable form is so perfectly preserved

that the plant seems to float freely as if in its liquid e1ement- Even the green often retains its lively hue.

“ Some of the large species of plants have been determined. Daunarrrox describes the Lichen rangiferinus and digitaius, plants possessed of forms which

no minerals could imitate.” This account is accompanied with an engraving of a plant (a hypnum)

occurring in Chalcedony, which agrees with a few in my collection ; but a great many others, I dare say, are undescribed plants in a fossil state, and worthy the notice of the scientific world.

It cannot be otherwise than interesting to the Geologists of Europe, as well as to those in India, to have a description of the various species of fossil plants occurring in the Sone agates, with engravings of a few of the largest ones ; and I will endeavour shortly to supply such a desideratum through your Journal as the fittest for such a

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Under this head we propose to insert the examinations of various substances sent to us by friends, of which they will he better able to look for the results here than in detached miscellaneous notices.—En.

1.—Sa1tness of the Red Sea.

The Hugh Lindsay, Steamer, having given currency to the report that the Red Sea contained more salt than the ocean, and that in consequence she liad been obliged to blow off much more frequently while in that part of her voyage, Lieutenant Buanns, on his return to India on board of her, took the precaution of filling two bottles, one with the water of the Red Sea, the other with that of the Arabian Sea, which he was so kind as to send to me under charge of Lieutenant FRASER.- (See Proc. Asiatic Society, page 410.)

After being allowed to stand for some hours side by side, to acquire the same temperature, their specific gravity was taken in the most accurate manner.

No. l, Arabian Sea water, spec. grav. l'O254 at 86°‘l
2, Red Sea water,.. .. . . . . . . . . .. 10258 at 86°~2

The difference is certainly in favor of the latter, but it is much too small to cause any sensible effect in the blowing off. '

Equal portions of the two were then analysed by the usual chemical tests, although the hydrometer result would have been quite sufficient to found a. judgment upon. It was thought that perhaps the lime might be in excess in the one case, and thus cause a quicker incrustation in the boilers; but both waters on evaporation began to be turbid

at the same time. The analysis was chiefly directed to the determination of the sulphuric acid and lime, the rest being performed in a rapid manner: the results were as follows on one cubic inch of each 1

Arabian Sea. Red Sea. Sulphuric acid, thrown down with barytes, 1'82 grs. 1'80

Lime, precipitated by oxalate of ammonia, 0'70 0'82
1000 grs. gave, with nitrate of silver,
chloride of silver, . . . . . . . . . . . . . . . . 80'00 8195
r: chloride of sodium, or common salt, 32'8 33'5

Although, however, the sea in mid channel may not differ materially from the broad ocean in its contents, it may be possible that in insulated positions near shore, under a fierce sun, concentration may proceed to a considerable extent—this is the only way in which I can account for the very difl'erent result published in the London Literary Gazette, on the authority of Dr. UnE's analyses quoted in Mr. Wn.KrNsoN’s work on Egypt.

The following is the paragraph alluded to :

“ During my stay on the coast of the Red Sea, I had occasion to observe the remarkable saltness of its water, and succeeded in ascertaining that it contained much more saline matter than the ocean. I have since been favoured by Dr. Unit with the analysis of some water brought by me from Berenice, from which it results that the specific gravity is l'035; that 1000 grains of water contain 43 of saline matter, of which about four grains are muriate of lime, with a little muriate of magnesia, and the remainder muriate of soda, with alittle sulphate of magnesia. The specific gravity of water of the open ocean in the same latitude is only l'O28, and contains not more than 36 grains of saline matter in a similar quantity."

To which the author attaches a note, explaining, that “ after the vernal equinox, the Red Sea is lower in winter ; but the prevalence of the south wind after the month of September causes a considerable rise of its level."

The difference in the two cases is not more than may reasonably be explained in the above manner. The hydrometer is in all cases the safest test, and it is apity that it had not been resorted to in the steam navigation of the Mediterranean, which has been the source of such contradictory statements.

2.—Native Carbonate zf Magnesia from South India.

In my analysis of the Nerbudda dolomite, published in the Gleanings in Science, vol. I. p. 267, I expressed a desire to obtain some of this mineral, stated by Dr. Tnomson to form “ whole rocks in Hindustan, and to contain much less carbonic acid than it ought,” though he was curious to know whether the interior portions of the mountain might not have their full proportion.

My wish has at length been gratified by Dr. MALCOLMBON, Sec. Med. Bd. at Madras, among whose specimens, recently presented to the Society, are several lumps of this curious mineral. Dr. M. writes:

“ The native carbonate of magnesia from Salem has again attracted attention. I at first supposed it to be a mngnesite, from the great ditficulty of dissolving it, but subsequent observation proved it to contain no silex. Its composition would seem to be, carbonic acid 475 ; water 40*; magnesia 48'5. As it is likely to become an article of commerce, and the statements regarding it are contradictory, I send some for your re-examination. It occurs in thin veins (from an inch to a foot), and also, (it is said.) in beds.”

As the atomic weight of magnesia dilfers materially in diiferent chemical works, I was anxious to make use of this mineral to set the matter at rest, and decide whether Bsnznuus, Tnomson, or Bmmns was most to be trusted.

Three careful experiments proved, that the water contained was 0'8 per cent., while the slight adulteration of silica left, on dissolving 100 grs., was only 0'3 ; traces of alumina and oxide of iron were visible in the form of adelicate brown gelatinous film on adding ammonia to the solution, but none of lime, even after adding sulphuric or oxalic acid, evaporating to dryness, and redissolving in distilled water. The solid impurities, therefore, being set against the gaseous, as nearly in the proportions of the magnesian salt itself, it is evident that simple calcination of the solid mineral will give a very exact view of its constituent proportions.

Ten specimens of 100 grs. each, treated in this manner, returned from the fire, weighing respectively, 49'67, 48'26, 48'20, 48-40, 48'40, 48‘38, 4839, 48'33, 48'37, and 48‘-38. The first of these was in the solid form, and therefore may not have been thoroughly calcined: the average of the rest gives,

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or almost precisely the composition according to this accurate chemistwhich it may be remembered was the only one which would agree with my analysis of the Jabalpur dolomite, a definite crystallized compound of one atom of carbonate of lime and one of carbonate of magnesia. To prove that no influential quantity of carbonic acid was retained, two of the specimens were dissolved in dilute nitric acid, in a closed glass tube-—the gas extricated was less than the 50th of a cubic inch.

' Dr. MALCOLMSON afterwards corrects this error. A part of the carbonic acid was driven ofl’ with the water. 1 By Dr. Tnomsorz, M. 46'2 G. A. 53-8; by BRAND! M. 47'2; C. A. 52'8.

The mineral was found to differ considerably in weight from the statements of THOMSON and Pnu.L1Ps--the specific gravity of two specimens being 2970, and 2'897, at thetemperature of 85°. A good deal of air was given off on its first immersion into water, and it adhered to the tongue.

Another point to be ascertained, from this mineral, was, whether the circumstance I noticed on the occasion alluded to, would hold true, viz. that calcined magnesia would not become a hydrate, like lime, on slak

ing, and that this earth might thus be recognized in mixtures.

Three of the calcined specimens were treated with water, which disengaged considerable heat, and then exposed in a receiver, over concentrated sulphuric acid, to be ridden of hygrometric moisture. After 30 hours, they weighed respectively 60-45, 587, 609 grs., shewing an average excess of 10'0, which is about half an atom of water (98). This result is so unexpected that it requires further examination, which

I hope to be able to give hereafter.
3.— Tin from Malacca.

Cast blocks of the metal of the principal mines, as prepared for sale, were transmitted by Ensign Nnwaonn. With reference to my observation in the 3rd vol. of the GLEANINGS, I was contented to test their purity by the specific gravity, which was as follows :—pure tin,

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Two specimens of the ore also accompanied :—

No. 1, from Luktit, a. fine grained black oxide- of tin, had a specifie gravity of 6'74, and yielded a produce of 70 per cent. of very good metal, on simple fusion, with black flux.

No. 2, from Srimenanti, was in much larger grains or lumps. It weighed, however, only 6'64 ; and yielded only 52§ (P) per cent. of metal-—-giving off some sulphur in the fire. It is therefore inferior to the former, but probably not to the extent stated in the above crude

and single reduction.
4.—Amer2'can Self-generating Gas Lamp.

Mr. LONGUEVILLE CLARKE has one of these curious and ingenious _

lamps, which are something on the principle of the little floating

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