PASTES.

Pastes are imitations of precious stones and of engraved gems, both camei and intagli, transparent and opaque, in coloured glass, and are manufactured in the following manner: A small iron case of the required size is filled with fine tripoli mixed with pipeclay, and moistened, on the surface of which an impression is made of the gem to be copied. This matrix is next carefully dried, and a piece of glass of the proper colour is placed upon it. If a stone composed of various strata is to be imitated, the proper number of layers of coloured glass are piled upon each other. The whole is then carefully placed in a furnace and watched until the glass begins to melt, when it is closely pressed down upon the mould by means of a flat iron, coated with French chalk in order to prevent the glass from adhering to it. It is then taken out of the furnace and cooled gradually, when the glass will be found to have received an exact hollow impression of the design first made in relief upon the tripoli. If it is required to imitate a gem full of flaws, as a Carbuncle or Emerald, the effect is produced by throwing the paste, when still hot, into cold water. This was, doubtless, the method followed by the ancients, except that they used a coarser material for their moulds, perhaps those terracotta impressions of intagli hereafter to be noticed, for antique pastes have a much rougher surface than the modern, and are full of air-bubbles. A curious fact, however, concerning them is that they are much harder than our common window-glass, and will scratch it in the same way as a splinter of flint does, whereas all modern coloured glass is softer than the transparent kind. This was due to the composition of the substance; for at present the German glass, which is made with soda, is greatly superior in hardness to the English, into which a large quantity of lead enters. Besides this superior hard

ness, other supposed marks of an antique paste are the beautiful iridescence with which its surface is often coated, owing to the oxidation of the glass by the action of the acids of the earth in which it has lain, as well as the bubbly and porous texture, not merely of the whole exterior, but also of the entire substance itself. This last peculiarity distinguishes the antique from the modern glass-pastes, which, when they imitate the transparent gems, are usually clear and homogeneous throughout, being, in fact, made out of pieces of what glass-painters call "pot-metal," or stained glass of one colour selected for the purpose; and these, from the greater fusibility of the material, usually show an even interior within the intaglio with difficulty to be detected from the work on But it may be remarked that this superior

a real

gem.

hardness may be found in pastes of the modern fabrique, if manufactured out of fragments of ancient glass, whilst the porousness and roughness of the cast will depend upon the coarseness of the sand or clay used in forming the matrix, and also upon the regulation of the cooling of the paste after the fragment of glass has been fused down upon the impression. Thus, at present, false Carbuncles and Emeralds

are made to show all the flaws and "feathers" of the true stones by cooling them suddenly when removed from the furAs for the iridescence so much valued by collectors,

nace.

I strongly suspect that it is often produced by artificial means, by the use of acids; for bits of window-glass, after a few years' exposure in a garden-bed, will be found with a surface as much corroded and as iridescent as that of the finest antique pastes.

the high

We have already remarked, under "] perfection to which the Romans had carried the art of making false gems, and the difficulty of distinguishing such from the true is frequently alluded to by Pliny. He also

10

enumerates the following kinds of coloured glass as employed for drinking-vessels:-" Glass like Obsidian is made for dishes (escaria vasa'), and an entirely red, opaque sort, called Hæmatinon. An opaque white is also made, and imitations of Agates, Sapphires, and Lapis-lazuli; and all other colours." Specimens of all these kinds are continually met with among the fragments of vessels found in company with Roman remains; more especially those imitations of the Sapphire here mentioned, a semi-transparent glass of the richest blue. Probably the finest paste in existence is an exact imitation of Lapis-lazuli, now preserved amongst the antique glass in the British Museum, on which is a threequarter figure, in half-relief, of Bonus Eventus, a naked youth holding a cornucopia. The slab is of considerable size, and has been worked all over with the wheel, or some similar instrument, after the manner of a gem cameo, and not simply cast, as is usually the case with antique pastes. Hadrian sent his friend Servian as a present from Alexandria (Vopiscus, Vita Saturnini) two cups of opalescent glass ("calices allassontes versicolores") given him by the priest of the Temple of Serapis, probably as a choice specimen of a national manufacture for which that city had been long celebrated.' Pliny also speaks of draughtmen made of

10 These fragments are collected by the Roman lapidaries, cut and polished and set in bracelets and brooches, where they show like Agates of the most novel and beautiful varieties, variegated with brilliant colours, arranged in wavy patterns. Blue with white stripes passing through its substance, and green similarly marked with red, were favourites of the antique glassworkers, judging from the frequency of such fragments.

The Egyptian glass-workers also produced small mosaics of the most minute and delicate finish, and sufficiently small to be worn in rings, and as pendants to necklaces, in the following ingenious manner. A number of fine glass rods, of the colours required, were arranged together in a bundle, in such a way that their ends represented the outline and shades of the object to be depicted, as a bird or a flower, exactly as is practised at present in

coloured glass of several varying tints, "pluribus modis versicolores,"

The art of making paste intagli was rediscovered by the Italians of the Renaissance, and afterwards brought to perfection by the Regent Orleans, under whose patronage the manufacture attained the greatest celebrity, and far surpassed any productions of the ancients in the same line.

Clarac gives the following notice of the origin of the Orleans pastes:-"Having engaged (1691-1715) the services of the celebrated chemist Homberg, and assisting him with his own hands in his operations (in a laboratory established in the Palais Royal), the Regent made him reproduce in glasspastes all the gems that he himself had collected, and also a large number selected from the royal cabinet. It is said that he manufactured six complete sets of these pastes, one of which Clarac himself possessed, the bequest of M. Gosselin of the Académie. It had been in his hands for many years, and was always regarded as one of the original six sets coming from the Regent's own laboratory. It had, however,

the manufacture of Tunbridge-ware. tion. The most beautiful specimen This bundle was next enclosed in a of this elegant art in existence is to coating of glass of a single colour, be seen amongst the gems of the usually an opaque blue: then the British Museum. It is a square of whole mass, being fused together, one inch, the ground a brilliant blue, sufficiently to unite all the rods into enclosing a kneeling figure of a one compact body, was drawn out winged goddess, Sate, in which the to the proper diameter. Thus the union of the pieces defies the closest rods all became equally attenuated scrutiny, and gives the effect of a without losing their relative posi- miniature painted by the finest tions, and the surrounding case of pencil, and in the most brilliant glass, when the whole mass was cut colours, which are brought out by through at certain intervals, formed the high polish given to the surface the ground of a miniature mosaic, of the slab. The back, left unapparently composed of the minutest polished, clearly shows the process tessaræ, put together with incon- of the manufacture. It formerly ceivable dexterity and niceness of belonged to the Duchess of Devontouch. Each slice of the finished shire, and was deemed one of the mass necessarily produced the same choicest treasures of her collection. pattern, without the slightest varia

been increased by the addition of several other pastes, probably made by Clachant and Mdlle. Falloix, who had been instructed by Homberg in this art, and became dealers in its productions. These pastes of the Regent are of very fine glass, or of enamel, and exactly reproduce the colours of the original gems. It is plain that they were produced with the utmost care; the material is very dense and free from flaws and air-bubbles; the intagli in them are clean, polished, and lustrous in the interior, a result extremely difficult to obtain. When held against the light, those which are transparent produce, by the richness of their tints, precisely the effects of the real stones. Some of them, however, particularly the Sardonyx, have been better imitated subsequently as far as the tone of the colour is concerned; but nevertheless, in spite of the recent advances in the art of glass-making, and in enamels, as well as in chemistry, it is very much to be doubted if finer pastes than these of the Regent could be produced in our times."

The new process was soon spread throughout Europe; and when Goethe visited Rome, in the last quarter of the past century, the making these glass pastes was a favourite occupation of the dilettanti residing there. At present the Romans display the very greatest skill in this art: I have seen some of their pastes, especially of the opaque kind, such as onyxes, that could not be distinguished from the real stone except by the file. To baffle this mode of detection, the dealers use the ingenious contrivance of backing the paste with a slice of real stone of the same colour; this being set in a ring, the junction is concealed, and when tested by the file enables the whole to pass for the real gem adorned with a valuable engraving. The same method is adopted for

2 Clarac mentions his having been shown a paste from an intaglio by

Marchant, and still retaining traces of his signature, which, having been