Closely based upon this latticinio—for the threads in a vast majority of cases are of an opaque white—is the famous Vetro di Trina or lace-glass. At the beginning of the last century the art of making this net-work decoration appears to have almost died out, but in the thirties and forties it was revived by Domenico Bussolin, and when later on more interest began to be taken in the Murano glass, it was to this vetro a reticelli that at first most attention was given. The details of the manufacture were described and illustrated by the well-known director of the Choisy glass-works, M. Bontemps (Exposé des moyens employés pour la fabrication des verres filigranes, 1845).
There is, however, a simpler and perhaps easier application of these bands of lattimo, in which they are applied in a series of festoons to the surface. In this case the opaque white enamel appears to have been laid on to the paraison at an early stage and dragged into crescent-shaped waves, so as to resemble closely the decoration of the little flasks of coloured glass from Egyptian and early Greek tombs—to those later examples more especially, from Rhodes and Cyprus, on which the colours are only applied to the surface (p. [37]), the resemblance in technique is very close. There are many interesting specimens of this festooned latticinio in the British Museum. In the case of the little biberon (Slade, No. 628) the festoons are worked into a palm pattern, identical with that often found on the little primitive vases.
I shall not attempt to follow in detail the manner of preparation of the true vetro di trina,—suffice to say that it is built up of a number of juxtaposed rods; these rods are arranged perpendicularly, side by side, so as to form a hollow cylinder, and into the midst a small vesicle of molten glass is inserted; to this the rods adhere, and the whole mass is then worked into the desired form. The rods themselves—they are similar to the canne supplied to the suppialume workers (p. [187])—may be either of opaque or clear glass, or they may be formed of elaborate combinations of the two (canelle a ritorto o merlate); the most complicated patterns are thus obtained. When two series of these rods are arranged to cross one another at an angle, we get a reticulated pattern, and within the reticelli thus formed a bubble of air may be caught up. There is, indeed, little opportunity for finding in this kind of work any free play for the decorative feeling of the artist, and the result of all these ingenious combinations of crossings and interlacings is only too often to give a tame and machine-made air to the finished vase or tazza.
The Opalised Glass, the Calcedonio[[152]] of the Venetians, is obtained by adding the same materials as in the case of the latticinio, but in very small proportions: it stands to the latter as weak milk and water to pure milk. In practice, I believe, the opalescence is often given by the addition of phosphate of lime in the form of bone-ash, sometimes, perhaps, by arsenious acid.[[153]] Pale blue by reflected light, it takes various orange and yellow tints when the light is transmitted through it. Such a vessel as the cylindrical goblet and cover of thick calcedonio in the Waddesdon Room at the British Museum, with a design in high relief representing the Triumph of Neptune, must have been cast in a mould.
We now come to certain varieties of glass which were much admired at one time, but are now little in favour. The aim, it would seem, in this class, as in the case of the old Roman prototype, was to imitate various kinds of precious stones and marbles. But the Venetians showed here little of the restraint of their classical predecessors, so that on the whole the colours, where not crude, are huddled together in muddy compounds.
An opaque red glass resembling jasper was probably known at Murano as early as the fourteenth century. In an inventory of the property of the Duke of Anjou (circa 1360) there is mention of a ‘pichier de voirre vermeil semblable a Jaspe.’ So in the next century, Charles the Bold possessed ‘Ung hanap de Jaspe garni d’or, à œuvre de Venise’—to judge from the expression used this beaker was also of glass.[[154]]
Already in a Milanese manuscript of 1443 (described below) there is a formula given for making schmelz by means of a mixture of certain salts of silver, iron, and copper, and before the end of the century we have Sabellico’s complaint that the modern murrhine glass was becoming far too common (see page 201); so that, on the whole, this family of marbled glass is, perhaps, as old as any other Venetian glass of which we have specimens. The examples, however, that have survived appear to be mostly of a somewhat later date. We find imitations of both classes of the Roman millefiori—the tints, however, are generally crudely matched—and especially several varieties of marbled glass with contorted veins of many colours. The schmelz par excellence of the Venetians (the German name would seem to point to a northern origin) is an irregularly veined and mottled mass, a somewhat unpleasant combination of bluish-green and purple tints, calling to mind certain kinds of slag—indeed it may have originally been made in imitation of some such substance. There are a few exceptionally fine early examples of this schmelz at South Kensington. Notice above all the spherical vase from the Castellani collection with cinquecento mountings and serpent handles of copper gilt; the greenish-yellow and pale blue tints are in this case harmoniously blended. To judge from the form of the bowl and stem, the cup of finely marbled schmelz at Hertford House cannot be dated much later than 1500. In this case, and probably in others also, the marblings are only on the surface; the interior is of a uniform greyish-green colour.
Of scarcely less importance is the splashed ware for which we can again find a Roman if not an Egyptian prototype. The splashes of enamel of various colours must have been scattered over the paraison at an early stage, for they have had to follow the changes of form given to the surface in the shaping of the vessel: we see them stretched out at the neck on the little burette in the Slade collection (No. 783). This splashed glass was much admired by the French and successfully imitated by them.
Something should be said of the painted Venetian glass of the seventeenth and eighteenth centuries. I say ‘painted,’ for such it is in general effect, although the pigments have probably in most cases been subjected to some kind of firing. The very poverty and dulness of the colours are indeed a proof of this; the artist’s palette has been subjected to the exigencies of the enameller’s muffle. We find landscapes with classical figures and amorini painted on the lower surface of bowls and rondelles (tondi). In the Dutuit collection, now housed in the Petit Palais at Paris, is a circular dish some fifteen inches in diameter, painted on the under surface, so as to be viewed through the glass; the subject, a dance of cupids, is treated in an exceptionally fine style and can scarcely be later than the middle of the sixteenth century. In many cases these designs have been added to Venetian glass by non-Venetian, sometimes by northern hands. This kind of painting or enamelling is, however, very subject to injury by use, and doubtless for this reason it is sometimes protected by a second sheet of glass. We have in such painted dishes a variety of the so-called verre églomisé to which reference has already more than once been made.
The Venetians at times drew designs on their glass with a diamond. There are some examples of this in a good cinquecento style in the Slade collection; but this work was confined to the pure scratched line, and even shading was not much used. It was not till the eighteenth century that they began to copy the later German methods of deep engraving and cutting with the wheel.