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the workman "became liable for the value of the Aessel destroyed. (Dig. 9. tit. 2. s. 27. § 29 ; see Salmasius ad Vopisc. Saturn, c. 8.) The art of etching upon glass, now so common, was entirely unknown, since it depends upon the properties of fluoric acid, a chemical discovery of the last century.
We may now briefly enumerate the chief uses to which glass was applied.
1. Bottles, vases, cups, and cinerary urns. A great number of these may be seen in the British Museum and all the principal continental cabinets, but especially in the Museo Borbonico at Naples, which contains the spoils of Herculaneum and Pompeii, and includes upwards of 2400 specimens of ancient glass. These sufficiently prove the taste, ingenuity, and consummate skill lavished upon such labours ; many which have been shaped by the blowpipe only, are remarkable for their graceful form and brilliant colours, while others are of the most delicate and complicated workmanship. A very remarkable object belonging to the last class, the property of the Trivulsi family, is described in the notes to Winckelmann (i. c. 2. § 21) and figured
here. It is a glass cup contained within a sort of network, also of glass, to which it is attached by a series of short and very fine glass props placed at equal distances from each other. Round the rim are several letters connected with the cup in the same manner as the network, and forming the words bibe vivas multos ANNOS. The characters of the inscription are green, the network is blue, the cup itself resembles opal, shades of red, white, yellow and blue predominating in turn according to the angle at which the light falls upon it. It was at first believed that this effect was the result of long interment beneath the ground ; but it is much more likely to have been produced by the artist, -for it corresponds precisely to the account given of two precious cups presented by an Egyptian priest to the emperor Adrian, and characterised as calices allassontes versicolores. (Vopisc. Saturn, c. 8.) Neither the letters nor the network have been soldered to the cup, but the whole has been cut of a solid mass, after the manner of a cameo, the marks of the wheel being still visible on the little props, which are more or less angular according as the instrument was able to reach them completely or not. But the great triumph of ancient genius in this department is the celebrated
Portland Vase, formerly known as the Barberim Vase, which is now in the British Museum. It was found about three hundred years ago, at a short distance from Rome, in a marble coffin within a sepulchral vault, pronounced upon very imperfect evidence to have been the tomb of Alexander Se-verus. The extreme beauty of this urn led Mont-faucon and other antiquaries to mistake it for a real sardonyx. Upon more accurate examination it was ascertained to be composed of dark blue glass, of a very rich tint, on the surface of which are delineated in relief several minute and elaborately wrought figures of opaque white enamel. It has been determined by persons of the greatest practical experience, that these figures must have been moulded separately, and afterwards fixed to the blue surface by a partial fusion ; but the union has been effected with such extraordinary care and dexterity, that no trace of the junction can be observed, nor have the most delicate lines received the slightest injury. With such samples before us, we need not wonder that in the time of Nero a pair of moderate-sized glass cups with handles (pteroti) sometimes cost fifty pounds (HS. sex minibus^ Plm. //. A7", xxxvi. 66). For a full description of the Portland Vase, see the eighth volume of the Archaeologia.
2. Glass Pastes presenting fac-similes, either in relief or intaglio, of engraved precious stones. In this way have been preserved exact copies of many beautiful gems, of which the originals no longer exist, as may be seen from the catalogues of Stosch, of Tassie, of the Orleans collection, and from similar publications. These were in demand for the rings of such persons as were not wealthy enough to purchase real stones, as we perceive from the phrase " vitreis gemmis ex vulgi annulis" (Plin. //. N. xxxv. 30.) Large medallions also of this kind are still preserved, and bas-reliefs of considerable magnitude.
(See Winckelmann, i.c. 2." §27.)
3. Closely allied to the preceding were imitations of coloured precious stones, such as the carbuncle, the sapphire, the amethyst, and above all, the emerald. These counterfeits were executed with such fidelity, that detection was extremely difficult, and great profits were realised by dishonest dealers who entrapped the unwary. (Plin. //. A7", xxxvii. 75.) That such frauds were practised even upon the most exalted in station is seen from the anecdote given by Trebellius Pollio of the whimsical vengeance taken by Gallienus (Gall. c. 12) on a rogue who had cheated him in this way, and collections are to be seen at Rome of pieces of coloured glass which were evidently once worn as jewels, from which they cannot be distinguished by the eye. (Plin. H. N. xxxvii. 26. 33. 75; Senec. Ep. 90 ; Isidor. Orig. xvi. 15. § 27 ; Beckmann, History of Inventions, vol. i. p. 199. Eng. Trans. 3d edit.)
4. One very elegant application of glass deserves to be particularly noticed. A number of fine stalks of glass of different colours were placed vertically, and arranged in such a manner as to depict upon the upper surface some figure or pattern, upon the principle of a minute mosaic. The filaments thus combined were then subjected to such a degree of heat as would suffice to soften without melting them, and were thus cemented together into a solid mass. It is evident that the picture brought out upon the upper surface would extend down through the whole of the little column thus formed, and hence if it was cut into thin slices at right