he type is given by carvings in rock crystal. We can point to no example of sculptured glass that can be compared t

ystal or of glass, somewhere in what may be called Upper Western Asia-in Armenia, Georgia, or Western Persia-and to refer ma

at Antioch and at Tyre. It was they, apparently, who carried on the old traditions in the manufacture of artificial pastes, coloured to imitate precious stones. The fusible glass containing lead of which such pastes were made had indeed been from an early date associated with the Jews-'Vit

se on alchemy that we must turn to find the earliest examples of those strange recipes for the manufacture, and especially the colouring, of glass, of which I shall have more to say later on. This connection between the arts of the glass-maker and of the alchemist arose from many causes, some of them obscure. For example, the vessels used in the experiments of the alchemists were from an early date made of glass. Again, the strange changes of colour observed when glass was stained by copper or by gold were regarded as steps to the great discovery itself. So that from the days of the Ptolemies in Egypt, if not fro

ed to enforce in the case of all books of magic. M. Berthelot, whom I follow for these early writers,[83] calls this papyrus the working notes of an 'artisan faussaire et d'un magicien charlatan.' This litt

shop (400 A.D.), married, and half a pagan; and to Olympiodorus, a priest of Isis, who in the sixth century kept up some of the Hellenic traditions. The late Byzantine scholiasts drew up summaries of these treatises and of ma

nabar (?), by litharge (?), and by a substance called calcocecaumenon, the latter word doubtless a corruption of the Greek equivalent of the ?s ?stum, or burnt bronze, the well-known medi?val source of an opaque red. Further on recipes are given for other colours to be applied as varnishes. There is also a chapter on the making of glass and some summary account of glas

-for that is unfortunately all that remains of this section-on unbreakable glass, on the soldering of glass, on the art of tracing trees a

later than the tenth century. The twenty-one little sections that make up his two books are written in hexameters, and treat of The Colours and Arts of the Romans. A third and much larger book in prose, t

recipes; for these strange ingredients there may have been originally a cryptic interpretation, but we should perhaps rather take the pretended necessity of their employment as a sign that the art of cutting glass had been lost. Then in section v. follows the account of the writer's attempt at imitating the gilt glass of the catacombs, which I have already analysed (p. 92). The description of the manner of cutting (secari) the cristallum in section xii. is more practical; we are told of a plate of lead mounted on

ercially and artistically. The trade between the west and the east, when not interrupted by the wars between the Greeks and the Sassanians, passed through Antioch, and after the Arab conquest the seat of the Caliphs was for a time at Damascus, a Syrian town. In the history of glass, from the very earliest times down to the Middle Ages, Syria, as represented by the coast towns a

ions from Greek, above all Alexandrian Greek, writers, from Zosimus and especially from the pseudo-Democritus. They deal with alchemy, that is to say with 'applied chemistry' and the subsidiary arts. There i

hat you will-cups, bottles, boxes-as the Lord may permit.' If the vessels thus made tend to split during the manufacture, 'lay upon them a thread of melted glass. Shape the head and other parts, then put back the vessels in the furnace to reheat, and withdraw them gradually [that is to say, anneal the glass carefully as a final process].... If you wish the glass to be white, throw in some female magnesia [i.e. oxide of manganese, see p. 77], if blue, add four mithgals of burnt antimony.' The m

sides and not in the centre (?), so that the fire from below may rise towards the central region where the glass is and heat and melt the materials. The upper compartment, which is vaulted, is arranged so as uniformly to roof over the middle story; it is used to cool the vessels after their manufacture.'[85] We have also the description of a smaller furnace, which is perhaps that in whic

TE

L GLASS

TED MANUSCRIPT O

, which is attributed to the year 1023, has been carefully reproduced by the monks of Monte Cassino where it is preserved. The full-paged miniature is to be found in a chapter headed De Vitro; I can, however, discover nothing in the text that throws any light on our subject. In the illustration we see to the left a nearly naked workman who holds a mass of some green material, perhaps the frit; another m

hese early experimental workers. Still more interesting are the illustrations in the Syriac manuscript from which I have just quoted; in these, the modern chemist may recognise many familiar forms. The glass vessels have chiefly reference to processes of distillation. The most important is the alembic, a form easily made; the neck of

empire and was so eagerly absorbed by the first Arab conquerors, the interest in glass is only of a secondary nature,-the great question was

perhaps be referred to the end of the eleventh or to the beginning of the next century; but in spite of this early date the style of the book is modern compared with the medi?val compilations we have lately been considering. That the German monk Rugerus, or Rogherus, should have assumed the Greek name Theophilus is itself a significant fact. He was, it would seem, a hard-working goldsmit

ce possesses in the way of divers colours and mixtures, all that Tuscany knows of the working of enamels [electrorum operositate] or of niello [nigellum], all that Arabia has to show of works ductile, fusible, or chased, all the many vases and sculptured gems and ivory that Italy adorns with gold, all that Fr

d glass for windows. In a curious passage to be found in the prologue of this book, Theophilus tells us that he has 'approached the atrium o

aclius. All we can say is, that while the furnace of the later writer consisted distinctly of three parts-the main furnace with the glass pots in the centre, the fritting oven on one side, and the annealing oven on the other-in the earlier type of Theophilus there is no separate building for the fritti

ure is roasted on an upper hearth and stirred with an iron trowel, so that it may not liquefy, for the space of a night and day. Note here that the ashes of the beechwood are used directly without any previous lixiviation; such ashes would contain, besides some alumina, more

d with a piece of wood open out the aperture which now appears at the extremity to the full width of the glass tube. We have here a somewhat primitive method of forming a cylindrical manchon. The cylinder is now reheated in what is apparently a separate oven-the dilating oven; it is slit lengthways and opened out with an iron forceps and a piece of wood. When the glass has been smoothed out into sheets it is taken to the annealing oven, where the sheets are ranged on end against th

ed wood, and make the rod adhere to the lower end of the glass.[92] After reheating the glass, you now, with a piece of wood, widen and shape as you desire the opening where the tube was first attached. The foot is then shaped and hollowed. (If this foot is to be regarded as a separate piece, it is not quite clear how it is attached to the vessel.) The handles are fastened on by means of a string of glass taken from the pot with a slender rod of iron, and by similar mea

e cubes enamels are made to be set in gold, silver, and copper. In like manner it is by means of fragments of divers little vessels (vascula

ibed can be identified with that adopted by the makers of the Roman cemetery glass. In the next section is described the Greek method of decorating glass vessels with the same colours-green, red, and white-that are used in the cloisonné enamels (electra). With these colours laid on pretty thickl

about the constituents of the fusible enamels. The pseudo-Heraclius, on the other hand, has a chapter (viii.) telling how glass is made from lead (calcined previously to a powder)

a constituent of the glass, and this, I think, is the only reference to this substance to be found in Theophilus's chapter on glass. Here as elsewhere we may note that the word sapphirus is used as the equivalent of a blue glass paste (coloured probably by cobalt), and that it is referred to as a mate