صور الصفحة
النشر الإلكتروني

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 the 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, la 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 will 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 rez 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. • No. V.

21 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 strongly 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.

If to the above natural arseniates is added the second artificial 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 different 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 octaedral 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 shown, with regard to the action of muriatic acid upon a mixture 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 muriatic acid been used, the na. tural conclusion would have been, that the ore was a mixture, or ab 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 animal 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 foreseen.' P.240.

The Meteorological Journal concludes this part of the volume. The thermometer was froin 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 29.95. The hygrometer froni 95 to 41; its mean 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. Boards., 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 națural 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

general, are numerous and accurate, and often from works little known or with difficulty procured.

Among the coleoptera, -we follow the system of Linnrus, which still continues to be our favourite, -we find eight species of scarabæus; the cetonia Chinensis and the melolontha viridis, iwo new genera from Fabricius; seven species of curculio; three of cerambyx ; two of buprestis, the tenebrio femoratus, and the meloë cichores, the true cantharis of the ancients. Of the hemiplera we find various species, of the mantis, gryllus, cicada nepa, and cimex, with one only of the fulgora, F. candelaria. The papilios are grouped according to the fanciful analogy of the Swedish naturalist; and thirty-two species are enumerated, with some of the sphinges and phalenæ. Of the neuroptere we have only one genus, libellula ; and of the apteræ, aranea maculata, cancer mamillaris and mantis, and the scolopendra morsitans. The plates, we have already said, are executed with peculiar beauty; and in many, as in Mr. Abbott's work, a branch is added either of curiosity or of the tree on which they feed. We cannot notice every design, but shall mention some of the insects which either are rare or merit some remark.

It may be in general observed that these insects are not exclusively Chinese, and that indeed they are seldom so. To many of the descriptions miscellaneous remarks are added, which, though they break the chain of scientific delineations, are to us often pleasing and interesting. Those on the scarabæus sacer show no inconsiderable knowledge of the ancient Egyptian superstitions. The cetonia and curculio Chinensis are particularly rare, and the latter probably a non-descript. The C. perlatus and pulverulentus are equally uncommon, and have not yet been engraved. The buprestides are well figured ; and our author has cleared some of the difficulties arising from the inaccuracy of Fabricius, who has confounded the B. vittata and ignita; but the whole is still somewhat obscure.

The observations subjoined to the description of the mantis Aabellicornis are very pleasing; but in these auxiliary remarks, or rather in the references, we meet with some striking errors, as if the original authors were not understood by Mr. Donovan. The peculiar ferocity of the mantes, and their battles, in which the weaker sex is not spared, and their fear of the ani, are singular circumstances. It has been called the animal plaat, and is supposed to have changed its animal to a vegetable nature. Our author seems to think that it may conceal the seed of a clayaria, or some other cryptogamic plant; and he thus explains rationally what has appeared wonderful or incredible. Other authors have however offered similar explanations. It is styled the soothsayer, from its immovable posture, supposed to be the position of study or adoration ; but is only designed, which it preys.

by its resemblance to a leaf, to mislead the incautious insect on

The account of the fulgora candelaria is also entertaining, but too long. The author is not aware that the emission of light is voluntary; and, strange as the expression may appear, that light is separated by its motions or in its secretions. A branch of the chrysanthemum Indicum is added to the figure of the insect. The additions to the description of the cicada are also too extensive : it was thought to approach the divinitics, because its supposed food, viz. dew, is less gross than that of other insects. The veneration of the Athenians for this little animal is not explained very satisfactorily; and the inquiry would lead us too far. A branch of the laurus camphora is added. The tettigonia splendidula of Fabricius is a cicada, and singularly curious. It has not before been engraved.

The cicada limbata is the white-wax insect of China, and a branch of the tallow-tree is added. A copious account of these very singular substances is annexed. The animal figured by sir George Staunton seems to be the pupa only, and what is properly the perfect animal is represented from Stoll.

Several of the cimices are peculiarly curious, as the C. dispar, Stockerus, crucifer, Phasianus, Slanbuschii, and bisidus. These seem to have formed no part of

any other collection. The butterflies are known to be singularly beautiful; and we must pass over those of common elegance, and notice only such as are highly so, or peculiarly curious. The first of these is the papilio crino, which is represented on a branch of the flowers of the renealmia exaltata-a plant and animal, so far as our knowledge extends, which have not been engraver., and each possessing a brilliancy of colour almost unexampled. The papilio peranthus of Fabricius is peculiarly scarce : it is represented on a branch of the arundo bambos. No figure of the P. Laomedon of Fabricius has been published, except in the present collection. The P. Telamon is a new and undescribed species, taken during the late embassy to China. The P. rhetenor is a Chinese insect; and our author would make it a distinct species from the P. Menciais, did not the authority of Fabricius oppose the separation. Its colour is of a beautiful blue ; and it is represented on a branch of the thea laxa, the broad-leaved or bohea tea. The P. Vesta is peculiarly rare ; and the P. pyranthe has never been figured. It is represented on the melastoma Chinensis : the colour is a bright yellow. The P. Hesperia and alymnus are very uncommon: the latter is exhibited on a flower of the hemerocallis Japonica. The P. Jacintha and Gambricius, Jairus Antiochus, Bernardus, and Erymanthis, are also rare : many of these have never been engraveni.

Of the genus sphinx there are few Chinese species. The sphinx thallo is described. Mr. Donovan adds, with great pro

« السابقةمتابعة »