THE INDUSTRY OF ALL NATIONS.

whole mass may rise very gradually to a dull redness. The ash-pit is then closed, andthe management of the furnaces already described is begun, and the heat raised to thepoint of incipient fusion of the porcelain (full whiteness), when the flux (felspar,)fuses and vitrifies the glaze. The lesser heat, technically called warming (to lowrodness), drives off all watery vapor and contracts the porcelain, and the baking,which occupies from eight to fifteen hours, fuses the glaze and vitrifies the mass. Theporcelain cannot, however, be removed from the furnace under six or eight days, dur-ing which the kiln slowly cools, all its openings being closed, and the porcelain thusbecomes annealed (as is the case with glass), without which precaution, it wouldbe valueless. When the seggars are opened, the porcelain, if the whole manufac-ture has been properly conducted, will have a pure milk-white color, without anytinge of blue, but the surface here and there shows specks or stains which resultfrom the flaking off of small bits from the seggars, or from dust and particles ofcarbon which have found their way into the interior of the seggars. While thekiln has been filled below with glazed ware, the second story has in like mannerbeen filled with biscuit, where the temperature is not more than one third as highas it is on the first floor. The shrinkage which porcelain suffers is aboutthirteen per cent, as a mean for the linear contraction, but the total contractionin volume is near forty per cent. Allowance has, of course, to be made in themodelling for this reduction of size in the baking.

Porcelain Painting is an art closely allied to that of glass painting, the effectbeing entirely restricted, however, to reflected light, as the semi-opacity of theware forbids the use of all transparent effects. The pigments are eithermetallic oxyds themselves, or enamels and glasses, colored by the proper oxyds,and ground to a fine powder. When it is remembered that the desiredtints of color appear only after firing, it will be understood that porcelainpainting involves artistic difficulties unknown to the miniature painter, whoseskill is required to meet the demands of this beautiful art. Many of thepigments produce their appropriate tints only at a certain temperature,far less intense than that of the baking kiln, while others form compounds sofusible witli the materials of the glaze, that they would run at a temperaturebelow that required to fuse others. This fact divides the pigments into the easilyfusible colors (technically called muffle colors, because they require to be fired inan oven or earthenware box, called a muffle), and refractory colors , or those whichwill stand the utmost heat of the kiln. The latter may be put on with the glazeor beneath it on the biscuit surface, and do not injure the smoothness, brilliancy,nor hardness of the glaze, while the muffle colors require oxyd of lead to makethem act well, and are always elevated above the glazed surface, are sensibly feltas a raised surface, and are more easily worn away. The refractory colors areblue, with cobalt; green, with chrome; brown, with oxyd of iron, oxyd of man-ganese, and perchromate of iron; yellow with oxyd of tilanium, and black withoxyd of uranium ; and are all applied with silicate of potash or soda as a flux.Gold is applied to porcelain in the state of fine powder (as it is precipitated bysulphate of iron from its solutions), and is made to adhere by the addition of onetenth of oxyd bismuth, and rubbed up with thick oil or turpentine. The bismuthoxyd fuses to the glaze, and causes the gold to adhere so firmly, that it can beburnished with an agate.

It is in the department of painting and ornamenting porcelain that the mosttime, talent, and experience are required. Years are lavished on some of theelaborate vases and exquisite pictures of Sevres, Berlin, and Dresden. And thebest artists of modern times have vied with each other in producing cartoons forporcelain painting. Fragility aside, no work of man is more indestructible thana porcelain vase or tablet, and there is every probability that some such mementomay go down to future times as an index of the condition of art, refinement, andscience, in the nineteenth century; as the Portland vase has survived the splen-dor and wreck of the Roman Empire, a mute but most eloquent witness of its age.

The Parian statuary biscuit does not differ essentially from porcelain.

Tender or Soft Porcelain .—This differs from hard porcelain in being formedof an easily fusible mass, glazed with lead and borax. In fact, the tender porce-lain would be glass, if the materials were treated in the same way. The en-tire absence of alumina from the composition of the ancient Sevres tender porce-lain, forbids us to consider it as a porcelain. Its composition* was in 500parts: fused nitre, 110; common salt, 36; alum, 18; carbonate of soda, 18; gyp-sum, 18; sand, 300. This preparation was entirely set aside by the introductionof hard porcelain, and possesses now only an historical interest.

The English porcelain all falls under the head of tender porcelain, if we exceptsome of Mr. Minton’s hard porcelain, and the statuettes, which are almost solelyan English speciality. The English tender porcelain differs essentially from theancient Sevres, and is a true porcelain body made fusible by a flux of bone ashes, butthe glaze always contains lead. It is formed by the use of plastic clay, porcelainclay or kaolin (the comish stone , as it is called in England, is only a crude kaolin),burnt bones, chalk, flint, and sometimes soapstone. These materials are ground andsuspended in water as already described, for hard porcelain. A. frit or imperfectglass is formed of a part of these materials, by the addition of carbonate of soda,borax, and oxyd of tin, the latter being added to insure white opacity. Thefollowing shows the composition of—

THE FKIT.

THE MASS.

Cornish Stone,

40

Kaolin, -

- 33

Flint, -

- 28

Blue Clay,

- 45

Soda, -

20

Cornish Stone,

- H

Borax, -

- T

Flint,

- 3

Oxyd of Tin,

5

Burnt Bones,

52

Frit, -

- V

100

100

This mass is easily worked, because of the largo amount of plastic clay itcontains ; the goods are fired twice, first for fifty hours, and after dipping in theglaze slip, again for twenty-four to thirty hours. The glaze is usually a silico-borate of lime, soda, and lead, but the lead may be omitted by employing a lar-ger portion of borax, which is sometimes done. This glaze is soft and easilyscratched by the knife, but quite smooth and fit for receiving the ordinary painting.The reason why hard porcelain is not made in England, is understood to bethe absence of a suitable material for making the seggars.

Wedgewood ware is composed of a frit and of a clay composition, and fallsmore properly under this division than with earthenware. The beautiful formsand graceful ornaments of the 'Wedgewood ware form a signal instance ofthe importance of securing the highest talent for design, where an estab-lishment would aim at the best results of which any given art is capable. TheEnglish courts present some examples of fictile wares, where the essential prin-ciples of design in such matters seem to have been overlooked, and all referenceto a subordination of the ornamental work to the use and outline of the whole for-gotten. While works of this description, with their exquisite wreaths and bouquetsof flowers, and other relievo and undercut ornaments, must excite our admira-tion for the skill of the artist, and his command over his plastic vehicle of ex-pression, they are inherently unfit for the position they occupy, as is shown bythe imperfect manner in which they have sustained the transportation andhandling necessary to place them on exhibition. Such ornaments in porcelain arefit only to be placed under a glass shade beside wax, and other artificial flowers,which may be seen, but not handled, qualities which we do not seek in a vaseor water jug.

It is hardly necessary to point out in the French court the beautiful objects whichthere attract universal attention. Here again we must refer to the pages whereseveral of these objects are to be seen engraved, and repeat that the productionsof Sfevres stand pre-eminent for every quality of taste and excellence of materialand manufacture. That Sfevres is an annual expense to the French nation, in avery considerable sum over and above all sales made of its high-priced wares, isonly saying that France has been, under all governments, sensible of the duty sheowed her arts and artists, to maintain in a liberal spirit a school of design in theceramic arts, which should be, as it ever has been, a model for the admiration ofthe world. The best science, and the most distinguished art which thecountry could furnish, have ever been in requisition for its management.Brongniart’s “ Les Arts Ceramique,” is the great source of information forall subsequent authors upon the history and practice of the ceramic art. Brong-niart, for forty years was its manager, and to him and Maleguti (also an employdof the government in the same speciality), we owe nearly all the accurate sciencewe possess in reference to every point of the porcelain manufacture. Ebelmanand Regnault have added their services in the same establishment; while in the de-partment of modelling and painting their artists have been workmen, and their work-men have had the spirit of artists. Who that has seen the Cupid and Psyche, the en-tombment of his mistress by a lover, and many other original works in the museumat Sfevres, but must at once feel the power of art to elevate and refine, and admire theunion of science and art, which has produced such almost miraculous results.

In the other branches of ceramic art, there is much that might be said withjustice and manifest advantage of the beautiful productions of Minton, Copeland,did our space permit as much detail as the subject demands. On another pagewe present colored illustrations of the encaustio tiles of Mr. Minton. This is thogreatest step in decorative architecture, which the ceramic art has made inEngland, and Mr. Minton has received at all hands the just reward of his eminentmerits as a most spirited and tasteful master in his art. The same exhibitor showsstriking and most beautiful examples of the old Majolica or Eaffaellesque ware,for garden seats, flower vases, &c., for a long time lost or in disuse; and lastly,he has revived the glazed friezes in blue and white, with figures, andother architectural ornaments, known as the Lucca de la Robbia ■ware, and ofwhich some of the finest examples extant are in Pisa.

We would not overlook the existence of the porcelain manufacture in thoUnited States, as indicated by the specimens shown by the United States PotteryCompany, from Bennington, Yt. We do not know why it should be styled“ patent flint enamelled ware,” as from the specimens of felspar, white quartz,and clay, shown as the raw materials of its manufacture, it is obviously a hardporcelain, of which the raw materials are superior to the skill which has beenbestowed on them. The results obtained, however, are very encouraging, and thospecimens of white ware sound, and in all respects of most excellent quality.

iss