« AnteriorContinua »
their terminations, they became so intimately connected with the choroid, as to form only one substance. On neither of their surfaces was there any thing similar to the nigrum pigmentum; the pigment was confined to the inside of the choroid coat, without any structure similar to the tapetum lucidum. The ciliary processes were affixed to the crystalline lens; they were extremely short and indistinct, not having that beautiful arrangement commonly seen in the eye of other quadrupeds. The iris was circular, and of a dark brown colour. The crystalline lens was somewhat remarkable, with respect to its form being nearly spherical; this was very strongly marked, when compared with the lenses of several other animals: the anterior surface was a little flattened.' P. 149.
These processes are apparently muscular: but what influence such appearances may have on the theory opposed by Dr. Young in the present volume, we cannot stay to inquire.
" VII. Demonstration of a Theorem, by which such Portions of the Solidity of a Sphere are assigned as admit an Algebraic Expression. By Robert Woodhouse, A. M. Fellow of Caïus College, Cambridge. Communicated by Joseph Planta, Esq. Sec. R.S.'
The demonstration of this theorem is incapable of abridgement.
VIII. Account of the Discovery of Silver in Herland Copper Mine. By the Rev. Malachy Hitchins, Communicated by the Right Hon. Sir Joseph Banks, Bart. K.B. P.R.S.
The silver is contained in the cross lode, chiefly on the eastern side, and it raises the copper lode. The · silver ore is a mixture of galena, native bismuth, grey cobalt ore, vitreous silver ore, and native silver, in the same proportions. as they are arranged. The rest of the lode is quartz, intermixed with iron, manganese and wolfram, with a small proportion of cobalt and antimony. As the lode of silver dips so low, it is not likely to be very productive, especially if there be no greater powers of raising water than the present steam engines possess.
IX. Account of an Elephant's Tusk, in which the Iron Head of a Spear was found imbedded. By Mr. Charles Combe, of Exeter College, Oxford. In a Letter to the Right Hon. Sir Joseph Banks, Bart. K.B. P.R.S..
It is not uncommon to find balls in the tusks of elephants; but we do not remember having ever heard of a weapon, urged only by human action, being lodged in this hard substance. Mr. Combe properly supposes that it penetrated through the skull contiguous to the root of the tusk.
X. Description of the Arseniates of Copper and of Iron, from the County of Cornwall. By the Count de Bournon, Communicated by the Right Hon. Sir Joseph Banks, Bart. K.B, P.R.S.
* XI. Analysis of the Arseniates of Copper and of Iron, described in the preceding Paper; likewise an Analysis of the red octaëdral Copper Ore of Cornwall; with Remarks on some particular Modes of Analysis. By Richard Chenevix, Esq. M. R. I. A. Communicated by the Right Hon. Sir Joseph Banks, Bart. K. B. P.R.S.
. These papers are very satisfactory, and show very clearly the great importance of crystallography, as analysis fully confirmed the arrangement deduced from the crystalline forms. Count de Bournon seems to be a very experienced crystallographer. The arseniates of copper are little known; they are not mentioned by Fourcroy in his late very comprehensive work, and we do not find any mention of them in the abbé Hauy's excellent system, now under our hands, and which we hope to be able to introduce to the English reader in our next Appendix. They occur however in Klap.. roth's Short View of the Mineralogy of Cornwall, long since translated and noticed in our journal.
It is with great regret we find it totally out of our power to, follow the very able author of the former paper in all his remarks. We can only observe, that he notices four species of arseniates. of copper;-1. That in the form of an obtuse octaëdron; 2. In hexaëdral laminæ with inclined sides; 3. In the form of an acute octaëdron; 4. In the form of a triedral prism.
. The arseniates of iron are still more rare. These were supposed by Klaproth to be arseniates of copper; but the real ingredient is iron, and the copper seems only to be an accidental mixture. The first species, the simple arseniate of iron, crystallises in perfect tubes, sometimes, though rarely, a little flattened. The form of the second species is a rhomboïdal tetraëdral prism, two edges of which are very obtuse, and the two others very acute.
Of Mr. Chenevix's very laborious and scientific paper we are still less able to give a satisfactory analysis ; for it is full of minute chemical erudition, and displays a very particular and comprehensive view of his subject in many points. The third species of the preceding paper is the most simple, containing only oxide of copper and arsenic acid, in the proportion of 60 to 39.7. The fourth species contains less copper and a proportion of water, in which some of the varieties of the third species agree. The second species contained also oxide of copper, arsenic acid, and water. The first species was of the same nature, differing only in the proportions. Various other analyses of similar ores are added, which we cannot follow. We shall therefore conclude our account of this part of the paper with two very important extracts. .
• With regard to the colour of some specimens of arseniate of copper, it is easily to be accounted for upon chemical principles. The mistake under which we have long laboured, that the green is the real oxide of copper, has happily been rectified by M. Proust, He has proved it to be a particular substance, (to which he has given tlie very improper name of hydrate of copper,) endowed with peculiar properties, and composed of the brown oxide, and of water, in a state of combination. From his experiments, and from what I myself have seen, I am inclined to draw the conclusion, that we have never yet obtained by art any real salt of oxide of copper. In exantining, for instance, sulphate of copper, we find it to afford blue crystals; and to contain a known quantity of water of crystallization, and of what we formerly called the oxide. But that oxide Kill retains a quantity of water, of which when it is deprived, it passes to a very dark brown, and changes its chemical nature and properties.' P. 204.
The second passage we shall select is our author's own recapitulation:
* In taking a retrospective survey of the experiments above re. lated, upon the various natural arseniates of copper which we have examined, we shall find,
. First, That natural arseniate of copper exists in three different states of combination ; the first containing 14 per cent., the second 21 per cent., and the third about 29 per cent. of acid.
Secondly, that each of these may contain different proportions of water, either as constituțing a hydrate, or as water of crystal. lization.
* Thirdly, that, upon losing its water, arseniate of copper will pass from blue to pale green, and finally to brown, as in No. I.
· Fourthly, that No. I. is the ouly real arseniate of copper, all the others being arseniates of hydrate of copper.,
• Fifthly, that No. I. is not to be admitted as an arseniate of copper containing 39,7 per cent. of acid. For, if we put it on the same footing with the others, in admitting a due proportion of water into its composition, we shall, by calculation, reduce it to that class containing 29 per cent.
• Sixthly, that, in beginning with that kind which contains the least quantity of acid, and rising progressively to that which contains the greatest, we shall find the order to be thus:
• No. VI. contains - - 14 per cent.
Nos. I. III and IV. . . 29 per cent. No. II. seems to be a particular species. It consists of a much greater proportion of oxide, with a less quantity of water, (and this its external colour announces,) combined with nearly the same proportion of arsenic acid. Indeed, if certain characters did not speak so stroncly in favour of this division, I should not have hesitated to class it with the last-mentioned kinds. But it is found in many states, which seems to indicate that the water is by no means in the same degree of intimate combination that it is in the others; and this alone may serve to distinguish it, to the eye of the mineralogist
1801. If to the above natural arseniates is added the second arti, ficial arseniate, we shall have another proportion of acid, at the rate of 40 per cent. Here then we have two simple substances combined in four different proportions, and producing seven distinct combinations.
• But, what is not the least to be admired, is the wonderful accordance in the order which two sciences, operating with very dif. ferent instruments, have allotted to the same substances. By that, not only the sagacity of nature becomes very striking, but, from the acknowledged accuracy of one method of investigation, the reliance to be placed upon the other is rendered more conspicuous, and each receives additional strength and confirmation. Chemistry has long been in the habit of aiding the science of mineralogy, of which it laid the foundation; but it was not till lately that crystal. lography could form a judgement of its own, much less confirin the truth of the source from which it sprung.' P. 216.
The third section contains the analysis of a red octaëdral copper ore, in which the metal exists in a state hitherto unknown in nature. Of the minute chemical observations in this section we can give no analysis, but shall add the conclusion
• From the foregoing experiments we may perceive into how many errors we may be drawn, if, in arguing from the results which we obtain, we pronounce too hastily upon the state in which a substance exists in the subject of any analysis. After what has been showni, with regard to the action of muriatic acid upon a mix. ture of metallic copper and black oxide of copper, both reduced to powder, and of the action of phosphoric acid upon the ore itself, it may be still a doubt whether this ore is really a suboxide, or a mixture of metallic copper and oxide of copper, at 20 per cent. of oxygen. But as similar proportions of both, after having been made red hot, presented all the properties and appearances of the ore much more strongly than when simply mixed, it is fair to conclude that it is a real suboxide. Had not inuriatic acid been used, the na. tural conclusion would have been, that the ore was a mixture, or at most a combination, of these two substances; for such did it appear to be by the testimony of the other acids. The truth is, we are but little acquainted with the exact state in which substances exist in many natural combinations. However, in the mineral kingdom, such fallacious conclusions are less frequently to be dreaded than in the vegetable and aniinal kingdoms. But in every research it is important to leave as little room for them as possible; and be who would indicate a sure and constant method of ascertaining whether, in many cases, what we deem a component part is not in fact a product of the operation, would render to science a service, the real value of which is perhaps not now entirely forescen.' P.240,
The Meteorological Journal concludes this part of the volume. The thermometer was from 88° to 22°; but, as usual, the superior extreme is too high. The mean heat was 51; that of April 51.5. The range of the barometer was from 30.45 to 28.75; the mean height 29.99. The hygrometer from 95 to 41; its mnean degree 79.2. The quantity of rain only 18.925 inches!
ART. VII.-An Epitome of the Natural History of the Insects of
China ; comprising Figures and Descriptions of upwards of One Hundred new, singular, and beautiful Species : together with some that are of Importance in Medicine, Domestic Economy, &c. The Drawings are accurately drawn, engraved, and coloured, from Specimens of the Insects; the Descriptions are arranged according to the System of Linnæus, with References to the Writings of Fabricius, and other systematic Authors. By E. Donovan, Author of the Natural History of British Insects. 4to. 41. 45. Boardsa, White.
THIS work is executed with peculiar beauty and accuracy; yielding, perhaps, in delicacy of colouring, to the Lepidopterous Insects of Georgia published by Mr. Abbott, but in no other respect inferior. We must however confine our commendations to the plates and the descriptions. Where the author speaks from himself, he is peculiarly unfortunate. Mr. Donovan delayed his publication till the event of lord Macartney's embassy was known; and though he regrets the issue' of this attempt, 'in common with every friend to the commercial advantages and scientific inquiries of this country,' he thinks it, on the whole, more favourable to the present publication than if the event had been different.' Does he mean that an extensive knowledge is less advantageous than a partial? or that, as he was determined to publish an epitome, it was lucky that more was not known? In either case the observation is peculiarly strange. He allows that if a general intercourse had been admitted between the two nations, and the language of China had been better understood, it is impossible to calculate the advantages which entomology, among other sciences, might have derived; for the Chinese, like their neighbours the Japanese, are well acquainted with the natural productions of their empire, and zoology and botany are favourite studies among them. He knows not to what extent natural history has been cultivated amidst this people ; but, by adding the Japanese, our author has saved us a troublesome investigation ; for we do know, from Thunberg, that the latter have very little knowledge of their own natural productions, and that the knowledge of the Chinese in natural history, as a science, is, pretty certainly, in an equal degree imperfect
In short, the author has contented himself with collections from different cabinets, and arranged the whole according to the "favourite' system of Linnæus. He ought however ta have known that Linnæus's is not a favourite system, and that, on the continent, it has been superseded by those of Fabricius and Olivier. The genera of the former are however added, and the synonyms of the latter in many instances; these, in