a true explanation of the cause of the adhesion of the coloring matter to stuffs. Berthollet, however, ascribes the theory of mordants to Bergman. This eminent chemist observed, that, when wool or silk was immersed in a solution of indigo in sulphuric acid, the former attracted the coloring particles more forcibly than the latter; and that both, having a stronger affinity for the indigo than the solvent, were by this means able to deprive the bath of its color, and attach it to their own fibres. Upon the same principle, he explained why the colors communicated to the wool were more durable, as well as more intense, than those communicated by the same process to silk.

On this principle, depends" the truly wonderful" art of calico-printing, which consists in communicating different colors to particular spots or figures on the surface of cotton or linen cloth, by placing it in a bath of compound dye, the rest of the texture retaining its original whiteness. This art was known in India, as already mentioned, at a very early period. To the uninitiated among the ancients, it must have appeared like magic; and, although the science of chemistry has laid open to the moderns so many mysteries and secrets of Nature, yet, even now, it is a matter of curiosity and admiration to behold a colorless texture, after being immersed for a short time, drawn forth, exhibiting figures of vivid and various hues, durably marked on its surface. This art is of comparatively recent date in England; but no branch of industry has risen to perfection with greater celerity. At present, the elegance of the patterns, the beauty and permanency of the colors, and the expedition with which the different operations are carried on, are highly admirable.

If we inquire into the cause of colors, we shall find that this depends not so much upon the chemical constitution of a body, as on a certain arrangement or disposition of the particles of the surface. Many bodies display different colors, according to the particular ansle under which they are viewed, while others assume a thenge of color, simply by the change of their mechanical lition.

Hence it appears, that color ought not to be regarded as a distinct principle, existing separately from the colored body, but merely as a faculty which the constituent elements of bodies possess, of reflecting particular rays of light decomposed at their surface. This fac

ulty may be variously modified; and we cannot tell what may be the color of a compound body, from the nature of the principles which compose it, when not previously ascertained by experiment. Frequently, two colorless bodies form a colored compound by mixture; and it often happens, that two substances, each of which has a very deep color, are rendered entirely colorless when united; while, in other instances, an entirely different color is produced than what might have been expected.

"Of all the arts," says Berthollet, "that of dyeing, perhaps, with respect to its theory, requires the most extensive knowledge of natural philosophy; because it is that which presents the greatest number of phenomena to analyze, of uncertain changes to ascertain, and of relations to establish with air, light, heat, and many other agents, of which our knowledge hitherto has been very imperfect." This is doubtless true; but what science has already effected, should operate as an encouragement to prosecute the study. It is surprising to see what new light sometimes breaks unexpectedly in, on the most abstruse and obscure investigations, and how much the ingenuity and diligent research of scientific men add to our real knowledge of Nature, even in those instances in which little is gained to the advancement of

art.

There may be much in the produce of the dyer's skill, as indeed there is in every art, to foster the vanity of a frivolous mind; but there is much also to elucidate the operations and the designs of that unseen Creator, who has so wonderfully filled every department of his works with incentives to human exertion; and who, in these works, every where affords food to the well-ordered

*See Spring,' Paper on the Color and Figure of Bodies.'

IV.

22

X.

mind, for the nourishment of a manly and enlightened piety.

NINTH WEEK-WEDNESDAY.

ARCHITECTURE.-ITS PRINCIPLE.

ANOTHER mode by which the human faculties are stimulated, under the remarkable system of Providence, is by the necessity to which man is subjected, of providing for himself the means of shelter. This is the first object of building; and the most simple want of this class, is that of a provision against the changes of the atmosphere, and the fury of savage beasts. The human mind, however, is seldom stationary; and, unless when coerced by the pressure of tyrannical power, or chilled by penury, or charmed to repose in the lap of plenty, is active and ingenious in providing itself with new comforts, and in extending at once its resources and its enjoyments. Nature herself affords the stimulus by which its faculties are kindled into action; and the spark, which the stroke of her hand elicits, is fed into an increasing flame, by the varied materials with which she abounds.

It is not long before society, under favorable circumstances, increases in its wants, and finds the means of gratifying them. Architecture, which ranks among the earliest of the arts, did not fall behind the rest in the race of improvement. What necessity engendered, was fostered by the restless propensity to change, the desire of possessing, and the ambition to excel. An increasing family, too, required extended accommodation, while numbers gave power, and combined ingenuity, invention. Thus, on the supposition, assumed for the sake of elucidation, that man was at first a savage, left to his own resources, he would gradually emerge from that state, and, as he rose, would naturally make progress in the architectural art.

At first, a natural hollow in the bosom of projecting

rocks might suffice for refuge from the inclemency of the weather; but even there, a barricade would be necessary to guard against external violence; and other inconveniences of such an abode, would quickly suggest the expediency of calling in the assistance of art. As the family enlarged, new chambers would be hollowed out, either communicating with the original cave, or placed at some distance from it, as circumstances rendered most convenient; while the materials removed in these operations, might suggest the idea of rearing habitations of stone on the adjoining plain. In other localities, the neighborhood of a forest, where summer shelter and protection were found under some leafy shade, within an enclosure of stakes, would suggest the idea of a wooden hut covered with leaves, the comparative warmth and comfort of which would recommend it for constant use, during the genial as well as the rigorous season of the year; and in the fertile and open plains, where neither of the resources already mentioned could be obtained, a pit dug in the earth, and elevated into walls above its surface, by the excavated materials, while reeds and grass furnished the roof, might give rise to the mud cabin so common in various parts of the globe.

This

As architecture advanced, notions of convenience would be improved, and ideas of beauty and proportion would be introduced, which would form the first germs of the principles of taste connected with the art. leads to a complicated and somewhat recondite question, into which I shall but slightly enter. Ideas of architectural taste seem to depend chiefly on two circumstances, utility as regards the object in view, and habit, arising from the original use of materials.

Mr. Alison, in his Essay on the Principles of Taste,' has discussed this subject with great acuteness. He has endeavored to show, that the beauty of proportion in architecture is resolvable into acquired ideas of fitness, and does not arise from any original law of our nature, or from any power of pleasing in the forms or objects. themselves. The beauty of external proportions, he tells us, arises from their apparent suitableness for hu

man habitations, when viewed from without, and consists in stability and sufficiency for the support of the roof. Thus, when the walls are of a proper thickness, and are placed at a sufficient distance from each other, to suggest the idea at once of stability and convenience, the building is considered as well proportioned; but when, on the contrary, the walls are so thin and high, or so distant from each other as to impress us with the idea of insecurity; or, on the other hand, so thick, so low, or so close together, as to appear to have been reared at unnecessary expense, or to have been inconveniently contrived, that building is reckoned to be ill-proportioned. Proportion, therefore, in those cases is merely fitness. We are here guided entirely by experience; and our sentiments respecting proportions are influenced by the nature of the buildings, and the materials of which they are composed. Edifices constructed of wood or brick, do not admit of being raised to the same height as those of stone; while a house, united with others, as in a street, may, without offending the taste, be carried higher than if placed alone; and a tower or spire, having only itself to support, may be elevated to a much greater height than any other species of building. These principles are all that seem to regulate the external proportions of simple buildings, and each of them obviously depends on fitness.

But besides this general principle, there are various associations which greatly modify the taste, while they exalt the enjoyment. Antiquity alone stamps a value on a particular form, while the costliness of the work adds an idea of magnificence to the sentiment. A still more powerful feeling is excited from national partialities. The style of each particular country or tribe, affects the taste in a degree not easy to be appreciated. When men have, from infancy, viewed a particular form, in connexion with the splendor of wealth and power, or the solemnity of devotion, it makes an indelible impression on the mind, in which the associations with these adventitious circumstances are intimately but unconsciously blended. Hence, the effect produced on natives by the style of building peculiar to their country; an effect