carbon, and nitrogen, so as to form this peculiar snbstance, and that I can unite this acid so formed, with iron, so as to make ferro-cyanate of iron, or Prussian blue. I find also that I can separate this peculiar substance from the iron so as to destroy the colour, and that I can re-unite them, and revive it interminably. I will now, with your permission, show this effect by a little experiment. Here are two bottles of liquid colour, the one a solution of indigo, well known, the other a solution of Prussian blue. I may be permitted to mention that Prussian blue was for a long time known only as a pigment, it being considered insoluble. About two years since I obtained a patent for a method of dissolving it, so as to render it available to many purposes, to which, as a pigment, it could not well be applied.

If I pour into this solution of indigo some of the contents of this bottle, which is a liquid chlorine, the colour will face, and in a short time become extinct. There is no method by which I can re

vive or reproduce indigo in this liquid, because its colour was rather a quality, and not an inherent property of its elements; but if I take this solution of Prussian blue, may decompose the colour, and apparently extinguish it; but as the property which produced the colour is still inherent in the materials, I can revive the colour by reviving the chemical affinities. By pouring a little solution of caustic soda into this blue solution, I form a prussiate of soda, which has only a slight yellow tinge, the iron being left free. If I now pour into this apparently colourless solution some acid, which has a stronger affinity to the soda than the ferroprussiate, I set the latter free, when it instantly unites by attraction to the iron, and the blue colour is revived. From this expe. riment it is easy to deduce the fact that the fading of the colour of indigo or vegetable colours, is an approach to a gradual extinction, but the fading of pure mineral colours is a change in their chemical affinities, but no dissipation or extinction of the property

of their elements.

To give you a further idea of the elementary nature of bodies and their inherent properties, I shall beg to exhibit one other experiment. These two bottles contain, as you see, two colourless liquids, yet one of them contains a black elementary matter, known as carbon; if I mix these two together, a decomposition will take place, and the black elementary matter will appear, proving that a colour, being an inherent property of matter, or combinations of matter, can never become extinct. I do not here intend to enter into the connexion and relation of colours to light, and I am aware that in calling black a colour, I may be considered to be in error, black being considered to be an

absence of colour. I beg to be understood to be speaking of the relative appearance of bodies.

From what I have now briefly stated, an inference may be readily drawn, that it is not to the vegetable or animal kingdom, although affording some of the most beautiful colours, that the painter must look for materials with which to perpetuate or reflect to posterity the genius and the works of art. It is to the mineral kingdom chiefly that he must turn for his most permanent colours.

Without detaining you long, I will endeavour to lay before you as brief a sketch or outline as possible, of the nature of mineral colours, and the causes which influence their permanence.

All mineral colours have metals for their base; and it is the union of this metal with some other element or elements which produces a colour. Oxygen, one of the components of the atmosphere, is the primary agent which combines with metals to produce mineral colours :-hence they are called metal

lic oxides; but as oxygen combines with metals in different proportions, different colours are produced. I have in these bottles various metals in different states of oxigenation, producing, as you see, different colours. That state of oxigenation which a metal is disposed under ordinary states of exposure to acquire, and which it is disposed permanently to retain, unless artificial means are used to reduce it, is its most permanent colour. Metals are influenced in their states of oxigenation by many external circumstances; some of them readily part with oxygen by light, heat, and moisture; and in proportion as they are more or less readily affected by these agents, are they more or less perma nent as colours. The combination of a me

tallic acid with a metallic oxide gives a fixed compound, which is a permanent colour. If I pour into this tube, which contains acetate of lead, a little of this bichroinate of potass, the acetic acid in the acetate of lead combines with the potass, and the metal chrome, which is in an acid state, unites with the lead, and you have thrown down the chromate of lead, or chrome yellow of the painters. If I put some of this, which is a solution of copper, I form the chromate of copper, which is a fine brown colour. Metals, in combination with sulphur, afford permanent colours, as vermillion, which is a sulphuret of mercury, and orpiment, which is a fine yellow colour - a sulphuret of arsenic. Metals also combine with carbon in two states, with carbonic acid it forms a carbonate; this is an example-the carbonate of iron. The direct combination of carbon with metals form carburets; this is a carburet of iron, commonly called black lead. These two bottles contain different preparations of manganese, the one a carbonate, the other

an oxide, in which the different colours are well observed, this is a carbonate of copper. Carbonate of lead, is the common white lead, An abundant source of permanent colours is to be found in the combination of metallic oxides, with earthy bases,-as alumine or clay, and silex. Iron, which is the most abundant and generally diffused of all the metals, is the most universal colouring material in the world. You can scarcely pick up a piece of dirt from the road, or sand or clay from a bank, but you will find with it, an admixture of iron. In travelling through the different districts of a country, you will observe the different colour of the earths composing the soil. In some you will find a red sand, as at Red Hill, in Surrey; in others a red clay,-oxide of iron is the colouring material. In another district you will find a yellow clay, it is iron in a different state of oxigenation, and less abundant.

Red and yellow ochre owe their colour to iron in combination with aluminous earths. The colouring matter of the Umbers is iron, of the Sienna, and the Terra Sienna. The red bricks and tiles of houses owe their colour to oxide of iron. Buildings which have been erected centuries since with red brick, and which are crumbling into dust with age, will be found to exhibit, comparatively unchanged, the per-oxide of iron. Iron is the colouring material of many of the gems and precious stones. Metallic oxides have the property of combining with vegetable and animal colours, and of prolonging their durability, and in this combination they are called the base. Thus, the beautiful colour extracted from the cochineal insect, has its colour heightened and preserved by being combined with the oxide of tin, which combination is the beautiful scarlet of the dyers, and forms the carmine of the shops, better known to some under the name of rouge. Iron, in combination with vegetable matter, is the source of most of the black colours of the dyers; most vegetable matters are darkened by contact with iron. If you were to stir your tea with an iron spoon, you would convert it into an inky fluid. If you saw a piece of green oak-wood with a rusty iron saw, you will leave a dark stain upon it. In combination with the vegetable acid of galls, it forms the black dye of the dyers; and is the basis of black ink. Iron is, in fact, so abundant, that it prevails where it is little suspected, and where the commercial name of the article would lead to a different supposition of its nature. Those who are not acquainted with the fact, would scarcely suppose from the name, that the article known as black lead, does not contain a particle of lead, but is, as I have before stated, a carburet of iron. The copperas of commerce contains no copper, but is a sulphate of iron. The black oxide of manganese also, is a mixed ore, of iron and

manganese. The crude oxide of manganese, if dissolved and mixed with galls or vegetable astringents, will make a black colour, which might induce a belief, that an ink could be made from manganese; but if the iron is separated from the manganese, the latter will give no colour at all with galls, or only a dirty yellow.

Arts and Sciences.

MR. N. DUNN'S MUSEUM OF CHINESE
CURIOSITIES, AT PHILADELPHIA.
(Concluded from page 398.)

Bridges.-There are four accurate models of granite bridges, from one to four arches; the workmanship of the originals is of great beauty and durability, and really in them we discover the perfect arch, the most approved piers of the present day, and yet their bridges are so ancient, that the date of their erection is almost, if not entirely, lost. Having no carriages, they are merely used for foot pas. sengers, loaded cooleys, and an occasional horse or buffalo.

Summer-houses.-Four models of sum mer-houses exhibit the peculiar taste of the Chinese; some are plain, and others very ornamental, with their scalloped roof, bells, gilding, painting, &c., and furnished with miniature chairs, tables, &c., models of real things, every part being complete for the luxuries of tea and the pipe. Tea is the universal beverage; this is sold from eight cents the pound up to many dollars, and is an article on which some of their citizens expend a very large income. The working man carries it in his rude tea-pot to the fields, and drinks it cold to quench his thirst, while the more wealthy sip it on every occasion of ceremony, business, or familiar intercourse.

Paintings. The pictures and paintings are very numerous, and probably occupy the greatest surface in the collection.- Many of them were presented by distinguished men of China, and many were painted by the most celebrated artists of the principal inland cities, including the capital. They represent in the first place, all those scenes which are charac teristic of Chinese life in its detail, including a series showing every process of the tea manufacture, from the planting to the pack. ing up. There are large and handsome views of Macao, Bocca Tigris, Whampoa, Canton, and Honan, with its remarkable temples, &c. The portraits will astonish those who have seen only the paltry daubs usually brought as specimens of the art in China. There is one of the high priest of the Honan temple, and others of distinguished men well known in Canton, worked with the minuteness of miniature painting. This department comprises also a variety of paintings on glass, an art much practiced by the natives; pictures of

all the boats peculiar to the country; of rooms, their domestic arrangements; of all the costumes of people of rank; the furniture, lanterns, and, in short, of every variety of Chinese life, from the most degraded class to the emperor. The flowers embroidered on satin, &c., will attract the eye of female visitors.

A Chinese Room.-At the east end, faced by a very superb alcove brought from China, is a Chinese room. The alcove itself consists of wood deeply carved out of solid blocks; the carving represents figures of men, animals, birds, flowers, &c. The cutting penetrates through the whole of each piece, and forms a net work, the front being painted and gilt in the Asiatic taste, with the rich colours for which the nation is so celebrated. The screen is a fac-simile of those put up in the houses of the wealthy, to form an ante-room in their large establishments. This vestibule will be decorated with furniture, such as chairs, tables, stands, stools, vases, maxims, scrolls, &c., and in every respect will repre. sent a room as actually occupied by the rich. This screen-work extends over the tops of the cases the entire length of the north side of the room, and its effect, as seen by the writer, is extremely gorgeous, reminding him of the representations made in old illuminated manuscripts, before the invention of printing in Europe. The colours, violet, blue, crimson, scarlet, &c., are those employed by the illuminators, and lead one to believe that they imitated the Chinese.

Furniture, Books, &c.—In addition to the furniture contained in this beautiful pavilion, there will be also distributed in the saloon, a variety of Chinese domestic articles and uten sils. Two dark coloured and extremely rich book-cases, which might serve to ornament any library, will display copious specimens of the books of the Chinese, in their peculiar and safe binding, so rarely seen in this country. Specimens of their blocks or stereotyped wood, are also in the collection. The bookcases are made in excellent taste, of a dark wood susceptible of a beautiful polish, and in some respects they may be considered an improvement on our own. The chairs of different forms, large and capacious, made of wood resembling mahogany, with their appropriate cushions and footstools, are in a taste of refinement and comfort, which would have been creditable to some of our forefathers of New England, into whose parlours they might have been introduced without differing much from the fashion of fifty years since. The stools without backs exhibit their adaptation to a southern climate, in being partly com posed of China ware, marble, and wood.

There are also tables, such as ornament the rooms of the wealthy, gilt, and richly carved and painted; stands, inlaid with marble or precious wood, such as are placed be

tween every two chairs to hold the tea apparatus, or those various little ornaments or flower pots, of which the Chinese it will be seen, are so remarkably fond. There is also a common table, such as is in universal use, and has been for centuries, which will be recognized by our present generation as a fac-simile of the favourite eight-legged table of our great grandfathers, now thrust by modern fashion into the kitchen or garret. It folds up as those do, and the legs are turned in rings; this, like a thousand things in the saloon, proves that our common usages have been derived from China, where we are accustomed to believe they are centuries behind us. The vases and seats of porcelain are particularly rich and unique.

Natural History.-The brevity we have been obliged to use in the foregoing enumieration, has prevented the mention of much that would have interested the readers of this Journal, and we have to regret that the department of natural history must be also merely touched upon. It evinces the comprehensiveness of Mr. Dunn's plan to find, that even in this particular, nothing has been omitted which time, trouble, and expense could accomplish, and as one evidence among many, of the laborious nature of the occupation of bringing these things together, we may mention the care bestowed upon the numerous objects of science here concentrated.

A young gentleman of Philadelphia, well known there as an enthusiastic naturalist, Mr. William W. Wood, son of Mr. William Wood, made his way to Canton in search of objects of interest, in the reasonable expectation of bettering his condition. Mr. Dunn at once sought his aid to perfect his collection, and employed his valuable time for a very considerable period. He had a carte blanche to procure objects in natural history, yet some art and no little subterfuge were necessary, to persuade the Chinamen to collect articles of a kind in which they take no interest; prejudice and national feelings were to be overcome before they could be induced to make the necessary excursions by land and water, to spots where no foreigner could penetrate. By industry, money, flattery, and kindness, he succeeded, however, in amassing a great variety of birds, fishes, reptiles, shells, &c., and a few animals. Of these, all have arrived in good condition, with the exception of the insects; the butterflies, moths, &c., which when last seen in Canton were particu larly rich and curious, have suffered most by the delay in unpacking, and by natural causes.

Mr. Wood was indefatigable for many months in completing the herpetology of China; the conchology is fully represented in many rich and rare specimens; and one of the rarest birds, the mandarin duck, with its very peculiar plumage, will be new to many: the China partridge, and many beau