that the cataract is an obfuscation of the mere COAT of the lens.

VI. An Account of some Stones said to have fallen on the Earth in France; and of a Lump of native Iron, said to have fallen in India. By the Right Honourable Charles Greville, F.R.S.'

The little that this article contains, tends to establish the similarity of the stones said to have fallen from the superior strata of the atmosphere; but we shall, probably, at no great distance of time, have occasion to resume the subject with all the facts regularly before us. The account of the fall of a mass of iron on the earth, from the 'Memoirs of the Emperor Jehangire,' written by himself, is peculiarly curious, and connects the appearances of native iron with the other masses from the atmosphere.

VII. Observations on the Structure of the Tongue, illustrated by Cases, in which a Portion of that Organ has been removed by Ligature. By Everard Home, Esq. F. R.S.'

Mr. Home's great object, in this article, is to show that the tongue is not peculiarly irritable, as has been supposed. Parts of it, when diseased, have been taken out without inconvenience. A singular case merits particular notice. A person bit his tongue severely. No particular or violent inflammation ensued, but the tip of the tongue continued insensible. Mastication was inconvenient and unpleasant; and the sense of taste was destroyed. It is not, we believe, generally known or acknowledged that the sense of taste resides in the tip of the organ only.

VIII. Observations of the Transit of Mercury over the Disk of the Sun; to which is added, an Investigation of the Causes which often prevent the proper Action of Mirrors. By William Herschel, LL. D. F. R.S.'

Dr. Herschel's communications are always valuable, even on the minuter branches of the science; and, though we do not now, under his guidance, penetrate the immensity of space, or soar beyond the remoter suns, yet we cannot follow him on any subject without instruction. His observations on the planet Mercury, in its passage over the sun, are chiefly designed to show that the disk of Mercury is perfectly well defined without the smallest suspicion of an atmosphere, either from its appearance on the sun, or in the moment of emerging. It seems not to be flattened at the poles, unless its pole were in the centre, opposite to the eye; which would conceal the difference between the polar and equatorial diameter.

The causes which prevent the proper action of mirrors, are investigated by a series of observations in which this action was defective. They in general meet in the following conclusion, viz. that in order to see well with tele

scopes, it is required that the temperature of the atmosphere and mirror should be uniform, and the air fraught with moisture.' Every observation is satisfactorily explained by these causes, which are, perhaps, too much crowded in the theorem, viz. the uniformity of temperature and moisture in the air. Every observer knows, that, in the moment of impending rain, the air is peculiarly clear. Another source of improper action of the mirrors is too great heat or cold: the former lengthens the focal distance, the latter shortens it.

IX. An Account of some Experiments and Observations on the constituent Parts of certain astringent Vegetables; and on their Operation in Tanning. By Humphry Davy, Esq. Professor of Chemistry in the Royal Institution. Communicated by the Right Honourable Sir Joseph Banks, Bart. K.B. P.R.S.

This article is an excellent one, and displays a very intimate knowledge of all the refinements of modern chemistry on a subject of the greatest importance to the arts. The tanning principle, the tanin of the French chemists, is distinguished by its precipitating gelatine, and it hardens leather in consequence of this effect. Our author's first object was the analysis of galls. Five hundred grains of good Aleppo galls gave, by lixiviation with water and subsequent evaporation, 185 grains of solid matter; of which 130 grains were tanin, 12 consisted of mucilage and matter rendered insoluble by evaporation, 31 of gallic acid, and 12 of calcareous earth and saline matter. The fluid obtained by the last lixiviation of galls is of a pale-green colour, owing, in Mr. Davy's opinion, to a gallat of lime.

The next object was the catechu, formerly called terra Japonica. It is procured both from Bengal and Bombay; but these different kinds do not seem to vary in their sensible properties. In their effects on leather, the former appeared the stronger; but, on analysis, 200 grains of the purest catechu, in powder, from Bengal and Bombay, produced respectively of tanin, 109 and 67 grains; of extractive matter 68 and 73 grains; of mucilage 13 and 16; of residuum, chiefly sand and calcareous earth, 10 and 14 grains. The darkest specimens contained most tanin; the lightest most extractive matter. From the more miscellaneous analyses we shall select the following passage.

The experiments of Mr. Biggin have shown, that similar barks, when taken from trees at different seasons, differ as to the quanti. ties of tannin they contain: and I have observed, that the propor tions of the astringent principles in barks, vary considerably accord. ing as their age and size are different; besides, these proportions are often influenced by accidental circumstances, so that it is extremely difficult to ascertain their distinct relations to each other.

In every astringent bark, the interior white bark (that is, the part next to the alburnum) contains the largest quantity of tannin. The proportion of extractive matter is generally greatest in the middle or coloured part: but the epidermis seldom furnishes either tan

nin or extractive matter.

The white cortical layers are comparatively most abundant in young trees; and hence their barks contain, in the same weight, a larger proportion of tannin than the barks of old trees. In barks of the same kind, but of different ages, which have been cut at the same season, the similar parts contain always very nearly the same quantities of astringent principles; and the interior layers afford about equal portions of tannin.

An ounce of the white cortical layers of old oak bark, furnished, by lixiviation and subsequent evaporation, 108 grains of solid matter; and, of this, 72 grains were tannin. An equal quantity of the white cortical layers of young oak produced 111 grains of solid matter, of which 77 were precipitated by gelatine.

An ounce of the interior part of the bark of the Spanish chesnut, gave 89 grains of solid matter, containing 63 grains of tannin. The same quantity of the same part of the bark of the Leices ter willow, produced 117 grains, of which 79 were tannin.

'An ounce of the coloured or external cortical layers from the oak, produced 43 grains of solid matter, of which 19 were tannin. From the Spanish chesnut, 41 grains, of which 14 were tannin. And, from the Leicester willow, 34 grains, of which 16 were tannin.' P. 264.

Of the entire barks, the oak produced, in the quantity of an ounce, 61 grains of matter dissolved by water, of which 29 grains were tannin.

The Spanish chesnut 53 grains, of which 21 were tannin.

And the Leicester willow 71 grains, of which 33 were tannin. The proportions of these quantities, in respect to the tanning principle, are not very different from those estimated in Mr. Big, gin's table.

The residual substances obtained in the different experiments, differed considerably in their properties; but certain portions of them were, in all instances, rendered insoluble during the process of evaporation. The residuum of the chesnut bark, as in the instance of the strongest infusion, possessed slightly acid properties; but more than of its weight consisted of extractive matter. All the residuums in solution, as in the other cases, were precipitated by muriate of tin; and, after this precipitation, the clear fluids acted much more feebly than before on the salts of iron: so that there is great reason for believing, that the power of astringent infusions to precipitate the salts of iron black, or dark coloured, depends partly upon the agency of the extractive matters they contain, as well as upon that of the tanning principle and gal lic acid.' P. 266.

An ounce of the bark of the elm gave 13 grains of tanin; of the common willow, 11 grains; of Sicilian sumach, 78;

of Malaga sumach, 79; of souchong tea, 48; and of green tea, 41 grains. Tanin exists also in the juice of sloës, and in Port-wine.

These experiments contain many minute circumstances, of considerable importance to the chemical history of tanin, and the analysis of astringent substances, which we cannot enumerate. Some observations respecting its affinities we shall select.

In making some experiments upon the affinities of the tanning principle, I found that all the earths were capable of attracting it from the alkalis: and, so great is their tendency to combine with it, that, by means of them, the compound of tannin and gelatine may be decomposed without much difficulty; for, after pure magnesia had been boiled for a few hours with this substance diffused through water, it became of a red-brown colour, and the fluid ob tained by filtration produced a distinct precipitate with solution of galls. The acids have less affinity for tannin than for gelatine; and, in cases where compounds of the acids and tannin are acted on by solution of gelatine, an equilibrium of affinity is established, in consequence of which, by far the greatest quantity of tannin is carried down in the insoluble combination. The different neutral salts have, comparatively, feeble powers of attraction for the tanning principle; but, that the precipitation they occasion in astringent solutions, is not simply owing to the circumstance of their uniting to a portion of the water which held the vegetable substances in solution, is evident from many facts, besides those which have been already stated. The solutions of alum, and of some other salts which are less soluble in water than tannin, produce, in many astringent infusions, precipitates as copious as the more soluble saline matters; and sulphate of lime, and other earthy neutral compounds, which are, comparatively speaking, insoluble in water, speedily deprive them of their tanning principle.

From the different facts that have been stated, it is evident that tannin may exist in a state of combination in different substances, in which its presence cannot be made evident by means of solution of gelatine; and, in this case, to detect its existence, it is necessary to have recourse to the action of the diluted acids.' P. 269.

M. Seguin supposes, that, in the process of tanning, the gallic acid is absorbed, and the leather de-oxygenated; but this theory is, in Mr. Davy's opinion, without sufficient foundation. In tanning, some portion of extractive matter is absorbed, and adds to the durability of the leather. Where the tanin is in larger proportion, and the extractive matter in a less, the leather is hard, and liable to crack. Slow tanning, as it favours the union of extractive matter, is preferred by our author. In strength, half a pound of catechu seems to be equal to four or five pounds of oak-bark.

In the Meteorologic Journal,' the range of the thermometer was from 82' (more probably from 75") to 15, the

mean about 50°: the mean heat of April 51°. The barometer from 30.48 to 29.07; the mean, 29.91. The hygrometer was from 94 to 55; the mean, 76.3. The rain, 13.946 only!

ART. V.-Amadis de Gaul; a Poem in three Books; freely translated from the first Part of the French Version of Nicolas de Heberay, Sieur des Essars; with Notes. By William Stewart Rose, Esq. 8vo. 7s. Boards. Cadell and Davies.

1803.

IN 1560, Bernardo Tasso, the father of a still more celebrated poet, published at Venice a metrical translation of Amadis, under the title' Amadigi.' It consists of one hundred cantos, and more than seven thousand staves; and, like his Floridante,' was a popular poem in Italy, according to the account of Lodovico Dolce, even after the Italians had seen the superior efforts of his son.

The fable, however, of this celebrated romance is not remarkably adapted for the purposes of the epic poet. There is no singleness of end and aim in the conduct of the hero, no steady, persevering, skilful, daring pursuit of some one great and important achievement. The incidents are successive adventures, not portions of a progressive event. In the Iliad, and still more in the Jerusalem Delivered, every combat is a part of the main action; it affects the relative situation of the conflicting parties; it endangers the dispersion, or consolidates the confidence, of the besiegers; it excites not only personal hopes and fears for the antagonists, but a mightier solicitude for the fortunes of the enterprise itself. But, in the life of Amadis, almost any one prominent circumstance might be omitted without being missed: each is insulated and unconnected; one adventure precedes, but does not prepare for the next; and although each is marvellous and impressive, and affords occasion for splendid description, yet the result of relating them is likely to produce a mass, and not a whole; arms and legs, and trunk and head, but no entire body; a file or knot, rather than a groupe, of champions; a tale more of bustle than of business.

There is another fault in most of these biographic fables: we hardly preserve a sentiment of the hero's identity. In the first book Amadis is exposed an infant in a sort of floating cradle; in the second, he is in love with Oriana, and kills king after king. Now it is with epic as with dramatic poetry. So long as the imagined appearance, and disposition, and master-passion, of the heroes can, with probability, remain the same, so long we are content the poet should busy us with their affairs. The duration of the long action is not dis