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banks of the lakes is stated to be more than ten feet high and three inches in circumference! This fine bemp too furnishes an addi. tional reason for our seizing upon the Azores; for there can be no besitation in asserting that there are in this island (St. Michael's) one million of acres proper for the purpose (of growing hemp) which, at one-fourth of a ton per acre, the average here, would furnish Great Britain with 250,000 tons of hemp! The island is about 100 miles in circumserence,' or, stating its dimensions in a manner less vague, forty miles in length by six in breadth, and consequently, if there be any truth in Cocker, the whole surface contains 240 square miles, or 153,600 acres; that is, the surface of the whole island is not quite one-seventh part of that portion of it which our political economist proposes to plant with hemp.

Following our light borseman, in his tour round the island, to the valley of Furnas, our readers will feel considerable disappointment in being told that the handsome monastery, built of lava, and surrounded by lovely gardens, abounding with the most delicious fruit and odoriferous flowers, together with the reverend Padré guardian, and his twelve or thirteen pampered priests of the order of St. Francis, have no substantial existence, but are mere creatures of the brain.' The Caldeiras are well known, but the wonderful whirlpool, whose name he could not learn, and the river, whose waters are of a dingy red,' are also non-entities. The vast columns of boiling water,' so hot as to boil an egg in two minutes,' never exceeded 196° of Fahrenheit's thermometer; and is it impregnated vegetables with the sulphurous acid it contains, and thereby rendered it unfit for the food of man,' the poor people of the neighbourhood would not make use of it as they constantly do.

The iron mines of Pico de Fer, which at some former time be says were worked with considerable success, till. a subterraneous explosion took place and buried the miners and their utensils in the ground,' are not to be questioned, though never heard of by any of the natives; for, says our Dragoon Officer, 'I am indebted to a second explosion which led to the discovery of the tools and implements of the unfortunate miners, for the facts I have here disclosed.' . • At Porto Fermosa (Formosa) he takes up his residence with some mendicant monks, whose hospitality he repays by four pages of scurrilous invective, made up of malignity, blasphemy, and falsehood. 'Every convent, every chapel, every church, has its huckster's-stall, or shop, wbere a reverend commission-broker constantly attends;_but why repeat bis ribaldry ?- At the little Fillage of Formosa there neither is, nor ever was a convent, a chapel, of a church. Indeed we have a strong suspicion, from the violent raving which appears in every page against 'shaved heads;" that his own head might reap advantage from tbe razor, and that his faculties have been disturbed by the same fatal curiosity which drove a laybrother of the order of St. Francis and several others

quite mad.' Near Ribeira Grande, we are told there is an aperture in the side of a mountain, from whence a light vapour issues, which, if corked up, would generate an earthquake, or cause an explosion that would blow up the mountain. To this aperture our knight-errant placed his ear; when his trusty squire, who attended with a long pole to spur on the ass of his master, interrupted bim by an exclamation which sufficiently sbewed the perilous nature of enterprize in which he was engaged.

• I learned from him that of the numerous persons who put their ear to the aperture, from a curiosity similar to mine, they all became mad, instantly mad, and were never again restored to the light of reason, or the rational government of themselves.'-p. 154..

And the rationale of this phenomenon is clear and conclusive..

The mania is caused by the chemical action of the sulphuric and vitriolic acid of the vapour, which, by penetrating into the minutest pores of the brain subject to their action, operate as a solvent, or produce irritation by sheathing themselves in the pores of the body, in which they become mixed.'

Lest, however, this solution should not be sufficiently obvious, we are indulged with the choice of a substitute.

That as the vapour is composed of combustible bodies like metals, or the compound ones, as phosphorated hydrogen, sulphurated hydrogen, and the metallic phosphurets generated in the fiery abyss, from which the vapour ascends, it may become so impregnated with oxygen, as to possess that peculiar acid, which, if communicated to the brain, might act as a solvent or irritant till madness ensues.'--p. 157.

A tremendous epistle follows, of volcanic eruptions destroying • primitive plains covered with aromatic plants;' of earthquakes from the effervescence of marine and mineral contents,' the effects of which are sudden blasts, violent explosions, and a rumbling in the bowels of the earth ;' when this fermentation of vapours gets vent by an eruption of water and wind,” it upsets mountains from their bases. But his theory of volcanoes, and earthquakes, and dews, which the editor assures us ' is quite original," is too sublime for our comprehension. The prospect brightens towards the close, and we are told, that though St. Michael's is: bell within, it is paradise without. It is a paradise, however, which, if we believe the captain, cannot boast of many 'saintly souls. Page is heaped upon page, descriptive of the intrigues of amorous and sentimental nuns and libidinous priests; inventions of the most dull and clumsy order wbich might just as well have been produced in the laboratory of the Minerva Press as on the island of

St. Michael's, and which, indeed, are scarcely worthy of the lumber garret of that fashionable staple of fiction. In one of the inaginary convents erected by the captain,' we are entertained by a concert of music performed exclusively by nuns who played on french horns, fiddles, and flutes.' p. 189.

The manners and customs of the inhabitants of St. Michael's are so unlike the manners and customs of the Portugueze, either at home or in any of their colonies, that we shall not notice them. To each of the rest of the islands the author assigns a short letter. At Terceira he just stops to read the Captain General a lecture; gives the same dimensions to Graciosa and St. George, though the former is only two and a half, and the latter twelve leagues long; calls the channel between St. George and Pico a short ferry,' though it is full four leagues across; goes to Santa Cruz in St. George's, where no such place exists ; finds that wine is the staple produce of Fayal, which never exported a single pipe of its own growth; and swells the population of the islands to half a million, which is about three times the actual number, --but we shall pursue him no farther, being perfectly satisfied that he never set his foot on any of them, with the exception perhaps of St. Michael's. The book is evidently the compilation of one of those gentlemen who write travels by the fireside, and perform their voyages up four pair of stairs. From the miserable attempts at science, and the slip-slop jargon of chemical nomenclature, we suspect that the materials were furnished by some surgeon's mate who had obt. ined a few days leave of absence from his captain to make the ti ur of the island. We suspect, too, from the strangeness of the language, that the work has been got up by a foreigner, probably by the editor Mr. J.Haydo : thus we have · Fermozean beauties carnationed by the refrigerent element,'—but we will spare our readers the disgust to which it has been our lot to submit to in wading through the most contemptible trash (to use the author's own expressions) that was ever imposed on the public.'

Art. XIV. Experimental Researches concerning the Philosophy

of permanent Colours, and the best Means of producing them by Dyeing, Calico Printing, &c. By Edward Bancroft, M. D.

F.R.S. 2 vols. Svo. pp. 1121. London. 1813. "THE

HE art of dyeing is one of the most useful and the most

wonderful of all known arts; and, according to Mr. Chaptal, whom Dr. Bancroft quotes, if any art can inspire mankind with a noble pride, it is this art, which not only imitates, but even exceeds nature, in the richness, splendour, and permanency, of the colours that it affords. We are bound to suppose that there is some foundation for the opinion thus enounced by a philosopher so respectable as Mr. Berthollet : but we should find ourselves a little at a loss to demonstrate, with mathematical precision, what other utility the art of dyeing possesses, than that of affording employment and emolument to a great number of individuals, whose business it is to render it subservient to the innocent gratification of the taste and luxury of others, without any direct advantage of such a kind as can, properly be denominated 'utility; at least in the same sense that the production and preparation of food are understood to possess utility. We recollect, however, but one instance, in the þistory of all ages and all nations, of an individual who carried bis ideas of the propriety of pursuing utility only, to the exclusion of the mere gratification of the eye, so far as to refuse to use or wear any article of furniture or clothing. which had ever been submitted to the dyer's art: his coat was white, his hat was drab, and his shoes were brown, as nature had left the raw materials; but he found no followers, even among the sectaries whose principles he had in this manner practically caricatured ; and the consent of mankind, so universally and unequivocally expressed, must be allowed to be imperative, in rendering a compliance with custom, and taste, in these respects, almost as indispensable as a submission to the irresistible dictates of hunger, thirst, and cold.

The first volume of Dr. Bancroft's elaborate and valuable work was published in 1794; but it now appears with so many alterations and additions, as to possess a considerable share of novelty and interest. In the introduction, the author defines the sense in which he applies the terms characteristic of the different kinds of colouring substances; substantive colours being such as afford a permanent lint by simple application without mixture, and adjeca tive such as require a mixture with some other substance to fix them; this substance, serving as a bond of union, is called a mordant, though it is sometimes difficult to ascertain which of two substances that are mixed is the more properly considered as the colour, and which as the mordant. If the substances thus employed are mixed before their application to the materials to be dyed, the compound is called by Dr. Bancroft a prosubstantive colour; but it happens more commonly, that the colours are more effectually fixed, by applying the substances concerned in sụccese sion, as if the particles wedged each otherin, after their penetration into the pores of the materials. There is, however, a complete fallacy in Dr. Bancroft's reasoning on the effect of heat in opening the pores, so that the colouring particles may be compressed when they cool again (p. 90); since these particles are at least as much contracted by the effect of cold as the substances wbich

they penetrate, and often much more. That the colouring particles are only partially distributed in or upon the surface of the substance coloured, is evident from the mixture of two tints, when the materials producing them are applied in succession; and a fugitive colour, constituting one of those tints, is not found to be in any degree fixed by applying a more permanent colour upon it; so that a compound green thus constituted will generally fade into a blue. In many cases it might be supposed that the absorpson of oxygen contributed to wedge the particles more firmly into their situations; but it sometimes happens, on the other hand, that oxygen appears rather to be extricated than absorbed, while the colour is acquiring its lustre by exposure to the light, as Dr. Bancroft has found with respect to the Tyrian purple.

Of the mordants employed for fixing colours, one of the most extensively useful, and the most unequivocally entitled to the deRomination, is alum, which is attracted by the fibres of many animal and vegetable substances, and, remaining attached to them, serves to unite them to the colouring matter, by leaving its carth as a common bond of union. The name alumen is found in Pliny, and Beckmann suspects that it may be of Egyptian origin; it is true that, according to Kircher's vocabulary, the Egyptian word, synonymous with alum, is oben, but we find alom, signifying cheese, which may possibly have had some connection with ibe coagulating power of this bighly astringent substance. Dr. Bancroft observes, that alum, and its use in dyeing, must have been known to the ancients long before the time of Pliny, since they never employed tin, and either alum or tin is absolutely necessary for obtaining a scarlet from kermes.

Dr. Bancroft proceeds to trace the art of dyeing from the ancients, whom he proves to have been acquainted with many of the most important processes, through the iniddle ages, when it was but imperfectly preserved in Italy, to the latest improvements, as described in the works of Macquer, Keir, Henry, Berthollet, Chaptal, Vitalis, Scheffer, Poerner, and Dambourney, as well as to those which he has himself introduced, both in theory and in practice. He divides the body of his work into four parts; the first, after some general discussions respecting colour, and substances to be coloured, is devoted to the subject of substantive colours, whether animal, as the Tyrian purple, vegetable, as indigo, or mineral, as iron; the second to the adjective colours of animal origin, as kermes and cochineal, lac, and Prussian blue; the third to vegetable adjective colours, as weld, quercitron, madder, Brasil wood, and logwood; and the fourth to compound colours of various kinds, and particularly the mixtures which produce black dyes, and inks of all descriptions:

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