SEVERAL

On the Graphite or Black-Lead of Ceylon.

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ERAL years ago, splendid specimens of graphite were presented to me by one of my pupils, who brought them from the island of Ceylon, where, he informed me, the mineral occurs in masses varying in magnitude from the size of a nut to several inches in diameter, imbedded in gneiss. Mr J. Prinsep has lately, in the "Gleanings of Science," an interesting periodical published at Calcutta, published the following analysis of one of the varieties: Carbon 62.8, iron 5.4, silica 21.0, alumina 9.3, lime 0.2, magnesia 0.1, manganese a trace, and loss 1.2, 100. Suspecting, from the large proportion of earthy impurity in this analysis, that some of the matrix had remained mechanically mixed with the graphite, Mr Prinsep made the following additional analyses: 1. The graphite, uncleaned, left, as above, iron and earth, per cent. 37.2. 2. Roughly cleaned, left a residue per cent. 18.5. 3. Crystals selected with care, 6.0. 4. Another trial left the very small proportion of 1.2. The two last residua did not entirely dissolve in muriatic acid; indeed the former yielded 0.3 of silica on analysis. This statement is illustrative of the accuracy of Karsten's view of the composition of graphite, namely, that it is a mere modification of carbon, and the iron and earths are accidentally mixed parts*. The gra phite of the Himala Mountains yielded to Mr Prinsep the following ingredients: Carbon 71.6, iron 5.0, silica 15.0, alumina, &c. 8.4 = 100.0. The English graphite was found by Mr Prinsep to yield, hygrometric moisture 2.7, carbon burnt off with difficulty 53.4, iron taken up by acid 7.9, earthy impurities 36.0 100.0. As this variety was marked of “ superior quality," it follows that, chemically considered, it is inferior to the kinds found in Ceylon and the Himalas.

The Ceylon graphite, Mr Prinsep informs us, has only been known commercially for five or six years; the government had shipped small quantities of it to England by way of trial, and it answered so well, that they were induced to receive it, amongst other articles, in lieu of revenue, at a fixed valuation, when they were suddenly surprised at the quantity of this novel currency

* Karsten's interesting experiments on graphite will be found in one of the volumes of this Journal.

offered in payment. A large heap was thus accumulated; and as the island abounds in this mineral, and there are no padlocks upon the mines, as in Cumberland, it might soon effectually destroy the income of the Borrowdale Company, if introduced largely into the English market. The natives of Ceylon make no use of it.

Analyses of several Indian, Chinese, and New Holland Coals. By J. PRINSEP, Esq. Secretary to the Physical Class of the Asiatic Society of Calcutta.

THE following table, published in the Calcutta Gleanings of Science, comprises the results of several analyses of Asiatic and New Holland coals. The fourth column, containing the water expelled, is kept distinct from the three which follow it, under the head of composition, as it is usual to include all the volatile products together. Should the water be looked upon as hygrometric, the per-centage of carbon and ashes must be increased to obtain the true composition of the coal: thus the Baghelpur slate-coal, after deducting 10 per cent. of water, contains

From the last column in the table, it will be seen how totally unfit are most of the Indian coals for the purpose of making coke. The Burdwan coke, with the exception of one specimen, would contain nearly a quarter of its weight of earthy impurity; the Silhet would be still worse; the anthracite of Baghelpur would be nearly half earth; some of the mountain coal from Ava would yield a coke of better quality, but of very little density. The Chinese glance-coal alone forms a remarkable exception to this unfavourable conclusion against oriental coal, and deserves to rank at the head of the list in respect to its purity as a coke, although in specific gravity it does not come up to the character of the English fuel, neither has it the spongy texture which must contribute much to the glowing combustion of the latter. It will be remarked, that the ashy residue on the

348 Analysis of Indian, Chinese, and New Holland Coals.

analysis of English coke (No. 2), much exceed what should have been expected from the composition of the coal whence it was formed; this may be explained by supposing that portions of the ashes, probably the alkaline salts, are volatilized along with the gaseous matter, when suddenly decomposed at a high temperature; or that considerable variation exists in the quality of the material charged in the oven. Whatever may be the cause, the same deterioration might be looked for in the coking of Indian coal, which would tend to lower them still more in scale of comparison.

TABLE of Indian and other Coals analyzed at the Calcutta Assay Office.

* The coals above enumerated as anthracites are evidently bituminous coals.-EDIT.

On the Fossil Flora.

THE fact that we do not know more than a few hundred species of fossil plants, shews the impossibility of our pretending at present to form any very plausible estimate or conception of the nature of the antediluvian flora, and also the hazard of attempting, from the disappearance of a few species, in proceeding from one formation to another, to determine the abundance or paucity of families or classes of plants. It is surprising to ob serve naturalists characterising botanically whole antediluvian epochs, when they possess, as in the case, for example, of the second epoch, the period of formation of the new red sandstone, a group of twenty miserable remains, as the whole of the disposable riches from which such a result is obtained. It is evident also that we cannot, from the present fossil vegetable remains of single families, form any satisfactory inference as to the number of their species, because it may have depended in part on accident, or some unknown circumstances, that in one family many species and individuals are preserved, while in another but few remains are met with. In other cases the circumstances, although easily understood, are not attended to, and the number of fossil species found in the deposit, are considered as the full measure of what has been destroyed. Thus in the first epoch two mosses only, but sixty-four lycopodiæ, are enumerated; but this circumstance does not prove that mosses and lycopodia formerly existed in the proportion of 2 to 64; for it is very natural that gigantic lycopodium stems would more easily resist the storms of time than the dwarf moss; and although we on that account have only two mosses remaining from that period, it does not follow that they have not been more than ten times more numerous than the lycopodia.

It is doubtful if botanists can determine with accuracy even the family of the fossil species. Many of the remains at present considered as Lycopodiums, may prove to be Ferns, or even Pines, the Selaginites excepted. Many of the gigantic, so called Equiseta, resemble tree-like grasses. The Marsileaceae of the former world may have belonged to the ferns. The Voltzia has not yet been proved to belong to the Coniferæ, and as the

confirmation of the coniferous character will give a decided preponderance to this class of plants, in the period in which it occurs, we see from this example how uncertain single conclusions are, which have been considered as sufficient in regard to the prevailing character of many vegetable epochs. An error, which can be so easily committed, in endeavouring to determine fragments very difficult of determination, is doubly prejudicial, when we attempt to found on it a history of the gradual succession of the families of plants. The whole study of the ancient flora, the flora of an early world,—is based on such a system of the history of vegetation, and on the proofs that it rises gradually from below upwards in regular successive epochs of more and more perfect vegetables. But in order to judge of this history of vegetation, it is premised that we have previously ascertained the true succession, the internal gradation of vegetation, in short the true natural vegetable system. But who has discovered this system, and what are its characters?

Notice by Dr GRAHAM of Botanical Excursions into the Highlands of Scotland from Edinburgh this season.

THE growing attention which has been given here to botanical science, has been evinced in many ways of late years, and, among others, by the increasing desire to extend the sphere of observation from the Botanic Garden to the neighbourhood of Edinburgh, and thence to the more distant and alpine regions of Scotland. In my first excursion into the Highlands from Edinburgh in 1821, I was accompanied by Mr Macnab alone, and joined by Mr Mylne and Mr Drummond from Forfar. In 1825, I walked round the west and north of Scotland accompanied by one pupil only, Mr Home. In 1827 I walked over nearly the same ground with eight or nine pupils. Every year since, the party has been quite as large as the accommodations were at all adequate to receive; and in the last three years, I have been favoured with the company of friends, all of whom have added greatly to the pleasures of the party, and the acquaintance with bo tany which several of them possess, has greatly increased the means of exploring the wide extent of the only half-examined