The Decay of Glass
Before ending this preliminary chapter, a few words may be said of the changes that take place in glass in the course of time from the action of the surrounding medium.[[5]] These changes are in the main due to the moisture and carbonic acid contained either in the soil or in the atmosphere. Perhaps what is most striking in this action is on the one hand the apparently capricious and irregular way in which the glass is attacked, and on the other the great beauty of the iridescent effects that so often accompany the process of decay.
As to the apparent irregularity in the progress of the superficial decay, it would seem that, apart from differences in the chemical composition of the glass, much depends upon the preservation of the original smooth ‘epidermis.’ Once this is impaired, whether by accidental scratches or by the growth of fungus or lichen, the carbonic acid or the ammonia salts contained in the air or soil find, in the presence of moisture, a secure lodgment, and the work of decay proceeds rapidly. Thus in the case of the little flasks of primitive glass of which I shall have to speak in the next chapter, in one example it may be found that the smooth skin of the glass has for more than three thousand years remained absolutely intact, while in another specimen from a neighbouring tomb the glass not only on the surface, but far into the interior, has taken on a talc-like or porcelainous consistency, and the brilliant colours have for the most part disappeared.
There is no need to enter into the details of the chemical processes involved in this process of decay. Suffice to say that the action is one of the same nature as that which has played so important a part in the geological changes of the earth’s surface, especially in the disintegration of the granitic rocks. It depends upon the power possessed by carbonic acid, in the presence of moisture, of decomposing the silicates of the alkalis. The soluble carbonate of soda or of potash thus formed is then quickly washed out from the surface of the glass. There remains, in the form either of iridescent scales or of an opaque pearly crust, a layer consisting not perhaps of pure silica, but of an acid silicate of lime, alumina, or lead as the case may be.
Now a piece of clear glass may appear to the eye to be devoid of internal structure. But the ‘metal’ has, we know, in every case been subjected during the manufacture to a complicated series of involutions and doublings, to say nothing of the subsequent inflation if the glass has been subjected to a blowing process. When decay sets in—something similar may at times be seen in the case of a piece of wrought iron—this complicated formation is in part revealed, for it is evident that upon it the lines taken by the decay are in a measure dependent. On blown glass especially, the disintegration of the surface tends to result in a scaly formation resembling that of the shell of an oyster. As a result of the decomposition of light in its passage through these fine superficial films, and of the partial reflection from the back of the scales at various depths, we get those unsurpassed iridescent effects that we associate above all with the glass of the Romans. That these brilliant hues are dependent entirely upon the physical structure is well shown by the total disappearance of the colours when the surface of a piece of iridescent glass is moistened, as well as by their reappearance when the glass is again dried.
Lead of glass is much less liable to such changes, but where in such glass decay has once set in, the whole mass may be converted into a white horny substance.
In other cases the surface of a piece of clear white glass will become gradually filled with a series of minute intersecting fissures, which in time may penetrate the whole mass. When this change has been fully developed we get a true crackle-glass, not to be confounded with the frosted glass of Venice mentioned in [Chapter XIII]. This fissuring of the glass-mass in its various stages may be traced in many of the specimens of Venetian, Netherlandish, and English glass at South Kensington. When fully developed the effect is at times very beautiful.
The tints of coloured glass may, it would seem, change in the course of time. Colourless glass also, from which the greenish shades derived from protoxide of iron have been removed by the addition of binoxide of manganese, is above all liable to assume in the course of time a purple tint under the action of sunlight. Again, if sulphur be present in glass, as is the case where sulphate of soda has been employed as a source of the alkali, the soda salt may be reduced by any protoxide of iron that is present. The sulphide of sodium and the sesqui-oxide of iron thus gradually formed will both of them tend to give a yellowish tint to the glass.[[6]]
Changes of this nature may occasionally have come about in the stained glass of the windows of our Gothic churches—the flesh-tints, which we know were produced in early days by manganese, may in the course of time have become of a more pronounced purple hue.
CHAPTER II
THE PRIMITIVE GLASS OF THE EGYPTIANS AND SYRIANS
From a technical point of view the history of glass might be divided into three periods—periods, it is true, of very unequal length and relative importance.
The first of these, one more especially of archæological interest, would include all the glass made before the discovery of the process of forming a vesicle by blowing through a hollow tube. Nearly all the glass that finds its way into our collections would be classed in the second period; this would extend from the beginning of our era to the end of the eighteenth century. In the course of these long centuries, the work of the glass-maker has of course been influenced by the varying schools and fashions of different ages and countries, but technically there is no great advance to be noted in the work of the seventeenth and eighteenth centuries when compared with that of the early days of the Roman Empire; and this is still more true if we consider merely the materials employed, their preparation, and the methods of their fusion. But before the end of the eighteenth century a great change had set in. The manufacture of glass in England and France had become an important industry, and we enter upon the third or industrial period. With the general advance in mechanical processes that is so characteristic of the time, the old methods of the working of glass were swept aside, so that before the middle of the last century, whatever of interest was to be found in the manufacture and in its results depended upon anything rather than upon the artistic qualities of the glass made.
Now, as I have said, the characteristic and dominant quality of glass is to be found in its capability of being blown into vessels of varying shape when in a viscous and semi-fluid state. All glass then, made at a time when advantage had not yet been taken of that essential property of the material, we may class together in a primitive group. This line of demarcation is as important, to return to a comparison I have already made, as that between hand-moulded pottery and that thrown on the potter’s wheel. The objects made in the earlier period by primitive processes were mostly small, and their merit depended chiefly upon the brilliancy and the skilful juxtaposition of a few simple colours—they may for the most part be classed as verroterie.
It has long been acknowledged that it is from Egypt that our earliest specimens of glass have come. But until quite recently the greatest misconceptions have prevailed as to the age and the methods of preparation of Egyptian glass. Misled by an erroneous interpretation of what are probably representations of metallurgical processes, on the walls of Twelfth Dynasty tombs at Beni Hassan and elsewhere, it was inferred that the art of blowing glass was known to the Egyptians at least as long ago as the days of the Middle Empire; by others the art was carried back to a still earlier period. We now have almost full assurance that glass in a true sense was practically unknown to the Egyptians before the time of the Eighteenth Dynasty (say between 1600 and 1500 B.C.),[[7]] and that for at least a thousand years after that period all that was made was produced by a primitive process in which the blowing-iron found no part. We have, unfortunately, up to the present time absolutely no evidence to show in what country or at what date this new process—I mean the blowing of a vesicle of glass—first came into use. There is, as we shall see, some reason to look for it rather in Western Asia than in Egypt, but the important point to bear in mind is that it was only after the introduction of this process of blowing, first to Alexandria and then to the Rome of the early empire, that the employment of glass for objects of daily use became in any way general.
Glass, indeed, in these early days, whether in Egypt or in the Greek world of the Mycenæan age, was something very different from what we now understand by the term. We must ‘think away’ a great deal of the modern connotation of the word. We must, above all, think of the material in connection with the native precious or semi-precious stones that it more or less resembled, and which were used along with it for decorative purposes. We do not know the Egyptian name for glass, but probably, like the Greeks, they divided all the hard stony bodies used in the arts into such as were ‘dug up’—natural products, that is, which they found ready at hand—and such as had been artificially prepared, and above all previously melted (the Λίθος όρωρυγμένη on the one hand, and the Λίθος χυτή on the other).
If, as I have said, there is little evidence for the existence of glass in Egypt before the Eighteenth Dynasty, it is quite otherwise with regard to a very similar substance, identical almost in chemical composition—one whose history can be traced much further back. On beads of clear rock crystal, dating from the First Dynasty, and it would seem from an even earlier period in some cases, we find a coating of turquoise blue transparent glaze[[8]]—the very glaze, in fact, that has given a prevailing tint to the vast series of smaller objects of Egyptian art that we see in the cases of our museums. A similar colour, I may observe, continued in favour in Mohammedan times, and indeed gives a dominant note to Oriental art in contrast to the ochry tints of yellow, red, and brown prevalent in the West.
The Egyptians soon learned to apply this blue glaze—essentially a silicate of soda and copper—to the surface of other natural stones, and above all to a fritty porous earthenware, the so-called Egyptian porcelain. Such an alkaline glaze, indeed, will only adhere to a porous base of this kind, with which it becomes united on firing, by a chemical reaction, or at least by the solution in it of some of the silicates of alumina and lime in the clay. This glaze differs essentially from those used on true porcelain—these last are almost of the same composition as the ground they cover—but, as in the case of the glazes on porcelain, so the materials of the Egyptian glazes were probably first incorporated together in a partially fused frit which was then ground and mixed with water to form a soup-like ‘slip,’ into which the object to be glazed was dipped. There have been brought from Egypt a few rare objects carved out of a blue frit (probably similar to that used in the preparation of glazes), for which a very early date has been claimed. But such a frit is no true glass.
The Egyptians had from the earliest periods been adepts in the carving of native minerals and rocks, and evidently found great pleasure in the strange markings and contrasts of colour found on their polished surfaces. Already in pre-dynastic times they availed themselves of their native granites, porphyries and conglomerates; from these materials they manufactured those large, carefully turned vases of which so many have lately been brought from Egypt. For smaller objects—jewellery, beads, and inlay of various descriptions—they had command of a wide scale of colours—reds and tawny yellows from jasper, purple from the amethyst, greens from root of emerald and from a special kind of felspar, and blue from the turquoise and (at a very early period) from the lapis lazuli. But the stones to which they had recourse for their favourite blues and greens were rare, and they were therefore the more ready to find a cheaper substitute in glass. Again, in Egypt, no stone was in greater favour than the native alabaster,[[9]] with its bands and zig-zag lines of transparent crystals in an opaque base of a warm milky hue. But there was no play of colour in this latter substance, and its very softness restricted the uses to which it could be put. In glass they found a substance hard enough to allow of more delicate forms, and on it chevrons of yellow and white could be traced upon a nearly opaque ground of turquoise or dark blue. Some such origin in native stones we may perhaps find for the decorative motives of the little vases, variously known as phialæ, unguentaria, alabastra, which were in such favour not only with the Egyptians, but perhaps even more so among the inhabitants of the islands and coasts of the Mediterranean, during a period of at least a thousand years. It is indeed these little vases that are the most characteristic product of the first period of glass-making.
It is not too much to say that the little we know of the processes of these early Egyptian glass-makers is derived from notices on the subject scattered through the memoirs in which Dr. Flinders Petrie has described the results of his excavations, more especially from the report issued in 1894, on his discoveries at Tell-el-Amarna. In the introduction to the catalogue of the Egyptian Exhibition held at the Burlington Fine Arts Club in 1895, Dr. Petrie has summed up our knowledge on this subject. I will quote the description of the method by which, according to him, these alabastra were made.
2
1
3
SMALL VASES OF “PRIMITIVE” GLASS
1. EGYPTIAN, NINETEENTH DYNASTY. 2. PROBABLY FROM GREEK ISLANDS. 3. ŒNOCHOE, FROM THE SLADE COLLECTION.
‘A metal rod of the size of the intended interior of the neck, and rather conical, was coated at the end with a ball of sand held together by cloth and string. This was covered with glass, probably by winding a thread of glass round it, as large beads of this age are thus made. The vase could then be reheated as often as needed for working by holding it in a furnace, the metal rod forming a handle, and the sand inside the vase preventing its collapse. Threads of coloured glass could then be wound round it and incorporated by rolling; the wavy pattern was produced by dragging the surface in different directions, the foot was pressed into shape by pincers, the brim was formed, and the handles were put on. Lastly, on cooling, the metal rod would contract and come loose from the neck, and after it was withdrawn the sand could be rubbed out from the body of the vase.’
The wavy decoration thus obtained was of two types: (i) formed simply by a succession of crescent-shape curves, or (ii) by means of a double drag, the pattern assumed a form like a frond of palm leaves, or still more like these leaves plaited into a basket. (Cf. [Pl. II.])
The number of these little vases that can be definitely attributed to the Eighteenth Dynasty (say about the sixteenth or fifteenth century B.C.) is small, but it is worthy of note that for brilliancy of colour and for purity of the glassy paste, the early examples are unsurpassed in later times. This is certainly a remarkable fact, especially if we are to regard the art as a new one. I cannot enter here into the evidence that would seem to point to a foreign origin for this early Egyptian glass—it will be enough to mention the conquests of Thothmes III. in Syria, and the close relation of his successor, Akhenaten, the ‘heretic king,’ with Syria and Babylonia, as shown by his marriage, and by the famous Tell-el-Amarna tablets. As bearing on this question I may refer to certain paintings on a tomb of this age at Drag Aboul Neggah, near Thebes (reproduced in the Revue Archéologique, 1895, Pl. 15), which represent the unloading of a foreign trading-vessel. We can distinguish here the merchants offering certain objects of value to an Egyptian official; among these are certain striped vases which have been doubtfully recognised as of glass. In the hieroglyphics accompanying wall paintings of this period we more than once find that vessels of rock crystal and lapis lazuli are mentioned, as well as blocks of uncut stones, and neither by the hieroglyphics used nor by the representation of the objects would it be easy to distinguish the latter material from lumps of glass. Again, Syrian workmen are known to have been employed at this time in Egypt, and nowhere would this be more likely than in the immediate neighbourhood of the palace of the king at Tell-el-Amarna, where the glass-works described by Dr. Petrie were situated.
All this, however, is mere conjecture, while as an argument for the native origin of Egyptian glass we have the indisputable fact that the manufacture was carried on in the new town established by Akhenaten at Tell-el-Amarna (circa 1450-1400 B.C.). This is made clear by the discoveries of Dr. Petrie in the winter of 1891-92. Among the waste-heaps of some important glass factories he has found enough material to put it beyond doubt that glass was there prepared from its raw constituents. First, with regard to the frits, the essential preliminary stage in the manufacture of glass: as I have said, some such half-fused material must have been long in use by the Egyptians in the preparation of their blue glazes. Complete freedom from iron was attained in this case (just as in after days by the Venetians) by the employment of crushed pebbles of white quartz as the source of the silica. These pebbles served also for the floor of the furnace, and they were doubtless more easily crushed after being thus used for some time. The fritting-pans, to judge from some large fragments of frit that turned up, were shallow bowls some ten inches across. These pans were, it would seem, supported for firing by cylindrical jars resembling the seggars of porcelain works. The shape and size of the crucibles in which the frit was subsequently melted may be inferred from some masses of glass found in the rubbish. These masses had been allowed to cool in the melting-pot, and the presence of frothy and worthless matter at the top was a proof that the glass was not merely remelted in them, but prepared on the spot from the above-mentioned frit. The glass was left to solidify in the crucible, and when cold, the crucible, as well as the scum at the top, was chipped away, leaving a clear lump of good glass. Dr. Petrie thinks that this glass was not remelted as a whole for subsequent working, but that lumps of suitable size were chipped off, and these, being heated to softness, ‘were then laid on a flat surface and rolled by a bar worked diagonally across them; ... the marks of this diagonal rolling are seen on the finished rolls.’ The rods thus produced were now drawn out to form a cane, or, if previously rolled flat, a thin ribbon. Beads were formed by winding these canes or threads of glass round a wire, or rather round a fine rod of hammered bronze, for wire-drawing was an invention of a much later date; such rods have indeed been found with the unfinished beads still on them. Similar canes of glass were doubtless worked in to the sides of the little vases to form the banded and chevron decoration which I have already described.
The silica for this glass was derived, as we have seen, from quartz pebbles, but we have no information as to the source of the other important constituent, the alkali. It is known, however, that the glass of the ancients was essentially a soda-glass, made for the most part in maritime regions. Again, the possibility of obtaining an abundant supply of fuel has always been an important element in the selection of localities for glass-works. Now in the neighbourhood of Thebes fuel must always have been scarce and dear, and it is uncertain whether there was any source of soda near at hand. We may perhaps regard the glass-works of Tell-el-Amarna as due in the main to the caprice of that eccentric sovereign Akhenaten. They were probably started at his orders to supply the demand for the new material then coming into favour at his court. In so far as the making of glass ever became an industry in Egypt, we must look rather to the neighbourhood of the Delta for its development. There at least fuel would be more abundant, and there a supply of soda was at hand in the ashes of marine plants, even if the natron of the adjacent salt lakes was not yet used for the purpose.[[10]] But until a much later date, glass was always a somewhat rare substance in Egypt, and was, it would seem, never produced on a large scale.
I must now say something as to the source of the colours with which the Egyptians stained their glass. In the absence of any satisfactory analyses, we are strangely in the dark on this interesting question.[[11]] But everything points to the predominance of copper as a colouring material at an early period, so much so that we may perhaps consider—and this is a suggestion that has indeed been already made by a French writer—that the invention of glazes in the first place, and then that of glass, were offshoots of the metallurgy of copper, and that these industries may therefore be especially connected with the copper age. In any case, it was in all probability not, as in later days, a more or less transparent and colourless glass, but rather one of a pale or dark blue colour, that at the commencement formed the basis to which a decoration of other colours was added.
The famous blue of the Egyptians, of which we hear from Vitruvius and other later writers, was essentially a silicate of soda, lime, and copper. It should be borne in mind that without the presence of the first two bases—the lime and the soda—a good copper blue in glass or glaze cannot be obtained. Indeed in the case of porcelain and fayence, the blues obtained from copper have always been confined to various shades of turquoise, as in the well-known glazes and enamels of the Chinese and the French, and even these turquoise blues, always, as we have said, containing lime and soda as well as copper, have only been produced with great difficulty. The mastery of a complete series of copper blues, ranging through every shade from a blue-black to a pale greenish turquoise, we may thus regard as a special triumph of the old Egyptians. At one period a darker shade has been in favour, at another a paler hue, according as the lapis lazuli on the one hand, or the turquoise or green felspar on the other, was taken as the standard of excellence, so that the shade of colour of the glaze on a scarab or a bead may at times throw some light on its date.
Distinct shades of green, apart from greenish blue, were much less in favour with the Egyptians, nor did they ever attain to the brilliant tints of the malachite. A green glass, generally comparatively transparent, was indeed at times obtained when a certain amount of iron was present in the materials employed; but this was merely an accidental modification of the blue. The pale tint of the green felspar was also imitated in an opaque glass used for inlaying.
For their reds the Egyptians were content to imitate the colour of the jasper, and here again they had recourse to copper; the transparent ruby tints of the mediæval workmen, whether obtained from copper or gold, were unknown to them. Their opaque red glass owed its colour to the presence, in large quantities, of the basic oxide of copper. In later specimens as much as 15 or even 20 per cent. has been found; some tin seems to be always present, giving an opaque enamel-like appearance to the Egyptian red—perhaps the colour was prepared directly from bronze. We often find this red paste oxidised on the surface; the coating of green carbonate then gives it the appearance of a richly patinated bronze, the blood-red body only showing when the specimen has been chipped. It is an interesting point that in early times the use of this red glass appears to have been confined to inlaid work—that is to say, it was never worked up with glass of other colours. This was, no doubt, for a practical reason: during the elaborate processes of patting, shaping, and reheating involved in the old system of working, the materials must have been exposed to a strong oxidising influence, and the basic red glass would thereby have lost its fine colour; it would also, perhaps, have injuriously affected the neighbouring colours. Some such difficulties in the working together of glasses of various colours may have influenced the Egyptians in adhering to their old system of inlays, employing, that is, small pieces, separately cast or cut out in the cold from slabs of glass of various colours. In such inlays the red paste was freely used from early times. On the other hand, I do not think that this fine copper red has ever been found on a glass vase of Egyptian provenance. On a few rare examples of later date (note especially two alabastra in the Slade collection, Nos. 15 and 35) we find indeed an opaque red combined with other colours, and in one case it forms the base ([Plate II.]). This red paste is of a peculiar spotty consistence, and I am inclined to think that the colouring matter in these examples is rather iron than copper. In later days the Egyptians made use of another tint, a fine orange. This colour, indeed, would seem to be the only addition to their palette during a period of more than fifteen hundred years.
The purple tint derived from oxide of manganese was known from very early times; the colour has been found in the glazes of the First Dynasty. It was, however, rarely used by the Egyptians for colouring glass. In some of the little vases from the Greek islands and elsewhere it has, however, been employed to form a zigzag of the usual type upon an opaque white ground. If we so rarely find this amethyst purple combined with other colours, this is probably for a reason of a similar nature to that dwelt upon in the case of the copper red.
Next to the two shades of blue, the colour most frequently found on Egyptian glass is a yellow, at times of a full mustard tint, but more often of a paler hue. Feather-like curved chevrons of this colour, combined with turquoise and opaque white on a deep blue ground, constitute indeed the normal type of decoration in a whole series of these little vases. I can find no record of any analysis of this yellow colour, but we may well compare it with the fine yellow glazes of the Chinese where the colour is derived from a mixture of an ochry earth with an oxide of antimony. There is no doubt that this last metal was known to the Egyptians; it was used at an early period by the women to darken the outline of their eyes.[[12]]
What has been said of the colours used by the Egyptians applies equally to the whole series of this primitive glass, indeed to a large extent to the glass of the Romans as well. It will form, I hope, a solid introduction to the subject generally.
The little vases or unguentaria—by far the most important objects in this division of our subject—occur in Egypt in two forms. First, the true columnar kohl-pots, spreading out at the top in the form of a lotus capital. Secondly, globular jars with a pair of small handles: these jars are sometimes flattened at the sides so as to pass into the shape of a pilgrim’s flask. In a little vase of this latter form in the British Museum the paste is of a deep, somewhat translucent, brownish red ([Plate II.]), and this colour passes in other examples into a rich transparent honey-red or hyacinth tint. The colour in both cases is, I think, derived from iron.
Of quite exceptional interest is the little vase in the British Museum, bearing the prænomen of Thothmes III., painted in yellowish enamel round the shoulder. I say painted, for in this case the decoration is simply applied to the surface, and not incorporated into the glass, thus forestalling the later processes of enamelling upon glass. The vase in question is somewhat rudely formed; it is of an opaque paste of a remarkably fine turquoise hue, and the sides are decorated with three conventional trees also in yellow enamel. This vase has been regarded as the earliest dated specimen of true glass that is so far known to us.[[13]]
The British Museum has lately acquired a curious vessel of glass, five inches in height, somewhat of the shape of a Greek crater. The wavy, dragged decoration on a pale slaty ground calls to mind certain early vases of wood or stone painted with a similar design. This vase, together with a cup of azure blue transparent paste, comes probably from the tomb of Amenophis II. Another little vase in the same collection, of aryballos outline, has been shaped apparently by the lathe—so accurate is the form—from a mass of opaque turquoise paste of frit-like nature.[[14]]
It was in the tombs of Amenophis II. and III., in the Valley of the Kings, near Thebes, that the unique series of glass vases, now in the Cairo Museum, was found (excavations of 1898-99). On more than one of these is a cartouche, a rectangle of deep blue, containing the royal name, ‘inlaid’[[15]] in several colours. One comparatively large vase (several of them are as much as eight inches in height) is decorated by three rosettes in low relief. The twelve petals are of blue, green, and red (the latter colour quite superficial) on a white ground. Still more remarkable is a vase with galloping horses and negroes; in this case the design is apparently inlaid on the interior, and only seen through the transparent body.
The little pots for cosmetics, in the shape of truncated cones, are usually made of a turquoise-glazed fayence. Those of glass are very rare; one in the British Museum is decorated on a nearly black base with splashes of white enamel; this enamel is now suffering from some kind of efflorescence and is falling off in scales. On another fragment in the Glass-Room we find yellow and white splashes on a black ground. This splashed ware is characteristic, I think, of the later dynasties—the twentieth and the twenty-first. We are reminded by it of a similar application of enamel colours to glass that was much in favour in France in the seventeenth century.
Apart from these little vases, the glass found in Egypt is confined to pieces for inlay and to beads or other small objects of verroterie. For the inlay the glass was rolled into slabs and cut out in the desired shape, the surface also being often carved in low relief: in later times the separate pieces were usually cast in open moulds. Beside the colours commonly used in the decoration of the vases, we find also an imitation of the pale green felspar, and the use of a red paste is, as I have said, more frequent. The individual pieces of the inlaid designs—they generally represent hieroglyphics, and are inserted into a basis of wood—are sometimes of a considerable size; some kneeling figures of a late period, found near Tanis, are as much as four inches in height. Mr. Griffith found here, among the ruins of houses dating from early Ptolemaic times, some traces of glass-works, which allow us to supplement in a measure what we know of the manufacture in more remote periods. It may be remarked, however, that on the one hand no vases of the old chevron type were discovered—and this is true, I think, of all the finds of glass from later deposits in Egypt—nor on the other hand, as far as I am aware, have any specimens of blown glass been found even among Ptolemaic remains. At Tanis were found many small moulds of terra-cotta and limestone into which the molten glass was run—so, at least, says Mr. Griffith (Egyptian Exploration Fund. Tell Nebeshah. 1888). In earlier times, at any rate, the process seems rather to have been to press down into the moulds little pellets of glass in a pasty state.
In the Glass-Room at the British Museum may be seen an interesting collection of this later glass of Ptolemaic or perhaps Roman date, found at Denderah. There are many fragments of glass paste destined probably to be fitted into hollows cut in a wooden plaque, the intervening surface being covered with gilt gesso. Here, as at Tanis, the colours are practically the same as those found in the Eighteenth Dynasty glass, with the addition only of the orange-yellow tint to which I have already referred. It is in the centre of these wooden plaques that what are perhaps the largest pieces of Egyptian glass known to us are found. These are the scarabæi of opaque blue glass, at times so closely resembling lapis lazuli that their true nature has been in dispute. Even the white marblings and spots of the native stone are imitated; indeed, in one specimen in the collection of Mr. Hilton Price, the little grains of pyrites in the stone, so much admired by the ancients, have been imitated by paillettes of gold scattered in the paste. (Cf. the passage from Theophrastus quoted below, p. [35].)
1
2
3
ANCIENT EGYPTIAN GLASS
1. SCARAB OF GLASS PASTE IMITATING LAPIS LAZULI. TWENTY-SECOND DYNASTY
2. FLASK FOR COSMETICS, IN SHAPE OF COLUMN WITH PAPYRUS CAPITAL
3. PLAQUE OF “FUSED MOSAIC” FOR INLAY; FROM DENDERAH, PTOLEMAIC PERIOD
But the Egyptians made use also of other processes partaking of the nature both of inlay and mosaic. Taking advantage of the fact that pieces of glass when softened by heat adhere to one another—they are in fact in this condition as ‘sticky’ as partially melted sugar—they formed a mosaic of small rods of glass; these were heated to a plastic condition, and if desired drawn out to reduce the dimension of the design; when cold, transverse sections were cut, on each of which the pattern appeared. In other cases the design was excavated on the surface of the glass, the coloured paste pressed into the hollows when in a soft condition, and the whole plaque finally reheated so as to form a homogeneous mass. Some such process, at least, must have been adopted in the preparation of the large slabs, generally with a ground of deep blue glass, of which a fine series may be seen in the Egyptian department of the British Museum. Elaborate work of this kind dates for the most part from Ptolemaic and even Roman times. Similar processes we shall come across again, in the case of the millefiori glass and the inlaid wall-plates of the Romans.
It is but a comparatively small number of the little glass vases with chevron patterns in our collections that have come from Egypt; up to the present time, however, no trace of their manufacture has been found in any other country; and although we cannot attribute so early a date as the Eighteenth Dynasty of Egypt to any of the little glass jugs and amphoræ found in Greek and Etruscan tombs, this ‘Mediterranean’ glass is in every respect subsidiary to the Egyptian series.