570

FAC-SIMILE OF MAI. DEMIDOFF’S VENEERED MALACHITE.

[Ci. ass XXVII.

of n portion of vonorro<l malachite. The joints arc marked by fine dotted lines, and the darker portions represent the aiti’ici.ilmalachite breccia or cement. The dark lines represent the natural concentric markings of the mineral.

the air, break up into smaller fragments, rarely ■weighingmore than from one to about four pounds.

It is by no means a modem application of this materialto employ it in inlaying or veneering for various decora-tive purposes; and few palaces, or large public museumsin the principal capitals of Europe , are without specimens,marking the progress of the manufacture from time totime, ami generally regarded, from their great rarity,cost, and beauty, as worthy of being made Imperial andKoyal presents. It is, however, only lately that MM.Dkmidoff, the owners of the mine in which the mineraloccurs, have established at St. Petersburg a manufactoryunder the direction of M. Leopold Joffkiaxd, where,after numerous trials, and the expenditure of muchcapital, labour, and ingenuity, it has been found possibleto produce such works as those sent to the Exhibition.To MM. Dejiidofjf, the owners of this mine and factory,the Jury recommended, and the Council of Chairmenawarded the Council Medal, in testimony of the magni-tude and importance of the objects exhibited, theirextraordinary beauty and richness, the excellence of theproduction, and the application of various new methodsof manufacture. These are chiefly seen in the construc-tion of the doors, and more especially in the ingeniousand beautiful manner in which the pattern is adapted tothe material, the detached pieces of mineral being fittedto each other so as to preserve this pattern. They may Ialso be noticed in the nature of the cement, which, being !

they have been formed, and are adapted to every sinuosity !of the pre-existing layer ; here presenting a dark line, therea bright and light one, just as the solution of the moment, ;the day. or the hour, happened to be more or less impreg- jnated with colouring matter. Besides round concretions, ]sometimes almost spherical, and also depressions of the jsurface, the under-sides of this malachite are singularly :analogous to that of any large mass of calcareous tufa, in |presenting pendent finger-shaped stalactites which are also 1composed of concentric lamina?. The external surfaces ofthese concretions are frequently covered with a black oreof manganese, which usually falls on being touched.”— jMurchison’s u Russia and the U>al Mountains” vol. i. ipage 374.

mixed with broken fragments of the malachite itself,does not interfere with the plan, or in any way injure theeffect of the whole.

The working of malachite on a large scale is extremelytedious and laborious, and is understood to be thus con-ducted:—The fragments of the stone are first sawn intothin plates, the thickness of which, for plane surfaces,is about a line, and, for curved parts, a line and ahalf. This cutting is performed by means of verticalcircular saws: the blocks of malachite being cemented ona carriage, which, by means of a counterpoise, is made totravel along a small railroad placed on rollers, and is socontrived as to present the malachite in such a way as toinsure the required thickness, and keep the mineral con-stantly pressed against the saw. Fine sand and waterare continually supplied to the part in contact with theblock, and the latter is thus slowly cut through, butretained in its position by means of the travelling framealready described. As soon as a plate is cut otf, it isremoved, the machine reset to cut another plate, and thework recommences.

The portions intended for curved surfaces are cut bybent saws fitted to the required shape, an operation whichrequires a large number of saws, and great care in cutting,as it would not be safe to trust to cement for fillingup spaces, and some of the joints require to he very neat.

The next process in the manufacture is the fittingtogether the different plates, and cementing them. Forthis the first thing to be done is, to determine the patternwhich the markings of the malachite are to represent.When tills is decided on, the surfaces by which the sepa-rate fragments of the mineral are to be united are pre-pared, by the aid of wheels of copper, in such mannerthat for each joint two wheels are required, the project-ing parts of one fragment entering a corresponding recessin the other. Joints thus made are not easily noticed,being formed withfgreat accuracy, and not presentingany break or straight line to the eye. Until the establishment of their present factory by MM. Demidoff, thejoints were straight, having no reference to the naturalveins or lines of the malachite, and thus surfaces wereplaced together in which these lines were not continuous,