THE INDUSTRY OF ALL NATIONS.

harmony composed in the key of orange and blue, varied by the introduction ofmore brilliant and compound tints in small quantities. This combination wasselected as being peculiarly adapted to the interior. Sky-blue, which is confinedprincipally to the dome and ceilings, serves to give an appearance of loftiness andairiness; while its complement, diluted orange or cream color, not only balancesthe blue harmoniously, but throws a cheerful tint of sunshine over the whole ofthe interior. It has the further merit of being of a subdued hue seldom occur-ring in manufactured articles, and therefore serving as an excellent background tothe mass of objects exhibited.

The power of blue to give an effect of loftiness to the building was stronglyexemplified during the progress of the painting, by comparing one of the naveswhich had been decorated with another which remained unfinished. Theformer seemed more than double the height of the latter, although they are allof the same dimensions. It was equally interesting to observe, that the intro-duction of a variety of colors, into large spaces, has the effect of magnifying theapparent dimensions to a wonderful degree. Space and grandeur are elementsof so much importance in architecture, that we cannot afford their loss. If abuilding of great dimensions appear small, it is to be attributed, not to its fine pro-portions, as is sometimes alleged, but to a neglect of its projector to avail himselfof one of the most effective instruments of his art.

In accordance with the general character of the building, no ornament of clas-sical forms has been introduced. The only attempt to decorate by means ofdesign, has been in the use of mere geometrical lines and figures of a very simplecharacter, which have been executed by common workmen, assisted only by theuse of stencil patterns. The ceilings of the four lean-tos are all different,those of the galleries are of a fifth pattern, and the four naves have still anotherdesign in common. Thus the lean-tos, which can only be viewed separately onaccount of their remoteness, offer a variety among themselves; but to the spectatorlooking upward, a perfect uniformity in the galleries and naves is presented, abovewhich rises the dome, still varied in design but harmonizing with the rest. Thisportion of the decorations, which is of the florid Moorish character, rich in color,and flashing with a profusion of gold and silver ornaments, when viewed by thefavorable light of gas, forms a crowning grace and beauty to the Palace, impartinga fairy-like and magical effect to the whole.

The treatment of the exterior requires very few words of comment. It ispainted of a uniform bronze tint or olive, enriched by gilding all ornamentalfeatures, such as the quatre-foils, the pinnacles and railings. Where large surfacesoccur, a rich orange tint, in imitation of gold, has been substituted for gold-leaf,as more economical. "We have heard it objected to the decoration of the ex-terior; first, that by it the real material of construction is concealed; secondly,that the imitation of a more costly material constitutes a deception. In answer tothis, we claim the benefit of a distinction between counterfeiting the appearanceof a material and borrowing an arrangement of color suggested by it. In thepresent instance, no attempt to deceive has been made, but, on the contrary, theuse of bronze powder and all other expedients, by which painters endeavor tomake a perfect imitation of real bronze, have been expressly avoided. Since con-structions of iron require paint to preserve them from rust, we can conceive ofno consideration affecting the choice of color, other than the character of thebuilding itself and its relation to surrounding objects.

ULTRAMARINE.

T HE artist and the decorator are indebted to the science of chemistry for threeof their best and most permanent colors, and of one of these—artificial ultra-marine—the present paper contains the history. At the same time it is a strikingillustration of the manner in which science continually aids the progress of theuseful arts.

For many centuries, the beautiful stone called lapis-lazuli , has been knownand valued for its rarity and for its color, a rich, deep azure-blue, such as no othermineral possessed. It was brought from China, Siberia, and Persia; and it wasalso found on the banks of the Indus, disseminated in a grayish limestone. Itsrichly colored varieties were employed in the manufacture of mosaics, and spe-cimens of it thus used, may be seen in the mosaics of the Italian department ofthe Exhibition. When it occurred in masses of sufficient size, it formed the ma-terial of vases and similar ornaments, whose beauty was enhanced by their cost-liness. Magnificent slabs of lapis-lazuli still adorn some of the cathedrals ofItaly. The fragments of lapis-lazuli were scarcely less valuable than the masses.When pulverized and mixed with wax, resin, and linseed oil, and kneaded withwater, the mineral deposited a powder free from impurities, and of a blue colorunequalled for beauty and permanence. This blue received the name of ultra-marine, and was sold for its weight in gold. Its manufacture remained in thiscondition for many centuries, and its use therefore was very limited.

In 1814, Yauquelin, a distinguished chemist of France, found an unknown blue

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substance in a furnace, used for the manufacture of soda. Upon analysis, heascertained that its composition was the same as that of lapis-lazuli. Alumina,silica, soda, sulphur, and iron, the constituents of the precious mineral, had met,by accident, in the proper proportions, and formed it artificially. From this ob-servation, Yauquelin predicted the future manufacture of artificial ultramarine, bysynthesis, or the combination of the substances that compose it in their properproportions.

The predicted discovery was made in 1828, by Guimet, also a French chemist.The prize which had been offered for it by the Societe d'Encouragement, was givento him on confidential communication of his process to Gay-Lussac. Guimet hasnever made his process public, but the attention of other chemists being drawn tothe subject, other processes, or perhaps the same, were discovered and published byGmelin, Robiquet, Persoz, Koettig, and Brunner. The process of Robiquet,which seems to be the simplest and most practical of those published, is nsfollows:—

A mixture of two parts of porcelain clay, three parts of sulphur, and threeparts of dry carbonate of soda, is gradually heated in a close earthenware vesseluntil it ceases to give off vapors; the resulting green porous mass is washed withwater, and the blue powder, which remains undissolved, is again heated to rednessto expel the excess of sulphur. (Annalen der Pharmacie 10, 91.)

The manufacture of the artificial ultramarine on a large scale, dates from thistime, and has since rapidly increased, and this product will ultimately become asimportant an article of commerce as vermilion or white-lead. The price hasalready actually been brought down by competition between manufacturers andthe rapid increase in the demand, to something like half a dollar per pound, beingjust one six hundred and fortieth part of the cost of the natural ultramarine,formerly made from lapis-lazuli.

At the London Exposition in 1851, there were a number of exhibitors of thisproduct, among whom, Guimet, the first discoverer of the process, was judgedworthy of the highest prize, a Council Medal. Guimet is also an exhibitor in ourCrystal Palace, but it remains to be seen whether two years of improvement havenot enabled some of the great number of other exhibitors whom we have, tosurpass him in the art. It is very possible that the credit naturally attached to afirst discoverer may have had some weight with the jury of the London Exhibi-tion, but it would seem as if the non-publication of his process by Guimet shouldannul any claim which he may have on that ground over other independent dis-coverers. There are certainly many specimens on exhibition at present, which, onsuperficial examination, seem to be of a much deeper and purer azure color thanGuimet’s, but in such a delicate point as this none but the highly trained eye ofan artist can be trusted. There are other tests which must also be applied indeciding the relative values of ultramarines, besides the mere impression upon thesight. Thus the degree’W opacity, or the tody, as it is technically called, whenmixed with oil, is an important point. The artist’s practical test for deciding therelative values of two or more samples, is to mix each with about equalquantities of white-lead and oil, and compare the resulting tints. The samplewhich has the greater hody will of course exhibit the darkest color.

Ultramarine may be distinguished from Prussian blue, smalt, cobalt-blue, andall other blue substances whatever, by the following test: when diluted sul-phuric or muriatic acid is poured upon it, it is decomposed, with total loss ofcolor, and evolution of a fetid smell, due to the formation of sulphuretted hydrogengas. The presence of ultramarine in any substance which has been dyed or col-ored with it, may be easily detected by this test. The ordinary bluish-coloredletter paper answers to this test. On being wetted with the diluted acid, it isimmediately decolorized, and the presence of sulphuretted hydrogen gas in thesurrounding air is readily manifested, not only by the strong peculiar smell per-ceived, but also by holding over the paper a common glazed card, moistened withwater, which is immediately turned brown, a brown sulphuret of lead being formedby the action of the sulphuretted hydrogen upon the white-lead with which thecard is glazed.

The property of ultramarine mentioned above, of being decomposed by dilutedacids with loss of color, is taken advantage of in a process recently proposedby a German chemist for determining the relative values of ultramarines; butthe process is one which is not susceptible of elucidation to the general reader,and which cannot be executed with precision, except by the educated chemist.The best practical test for the use of the consumer, is that by mixture with oiland white-lead, as before described. It would be useful also to the artist to keepsome diluted sulphuric acid at hand, and ascertain whether his ultramarines arecompletely decolorized by being drenched with it, which would indicate theabsence of adulterations, such as Prussian blue, smalt, indigo, etc., because noneof these latter substances are at all affected by the acid.

There is another application of ultramarine, besides its use by the painters, towhich we must give some attention. The dyers and calico printers, whose artshave been advanced so wonderfully during the present century by the applicationof chemical science, and who, taught by experience, are always upon the gui vire,and eager to seize any new application, must have seen, as the artificial ultra-marine cheapened in price, the advantage which would accrue to them if they