In the third section we are told that earthenware may be glazed with a preparation of pounded Roman glass, mixed with water and gum and then carefully refired. The fourth section—_De Sculpturâ Vitri_—describes a method by which glass may be first softened by smearing it with a mixture of fat worms and vinegar, sprinkled over with the blood of a fasting goat that had been fed with ivy; the glass may then be cut with a hard stone called _pirites_. This association of goat’s blood and ivy occurs more than once in the old 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 iron, over which a certain hard powder is sprinkled. But here, too, the virtue of goat’s blood is not forgotten; by its means the diamond may be made to yield to iron. In section xiv. a process is described by which Roman glass may be melted and cast into moulds of chalk to form ‘fair shining gems.’ Heraclius has been called an ignorant quack, but he well represents the views of his time. Compared with him, Theophilus, who wrote in the north of Germany some hundred or two hundred years later, seems almost a modern. More important to us than any of these Western sources of information before the time of Theophilus, are certain Syriac manuscripts preserved in the British Museum and at Cambridge. For our knowledge of the contents of these I am again indebted to M. Berthelot (_La Chimie au Moyen Age_, vol. ii.). In the sixth and seventh centuries Syria had taken a commanding position, both commercially 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 at least, has vied with Egypt for the premier position; the two countries have always been closely connected, and at more than one time they were under the same ruler. When we come to study the glorious Saracenic glass of the thirteenth and fourteenth centuries, we shall find that Syria has perhaps a better claim than Egypt to be regarded as the original seat of the manufacture.