M. Berthelot has reproduced in his earlier work (_La Chimie des Anciens_) several rough pen-sketches of the apparatus used by the mediæval alchemists, taken from the St. Mark’s manuscript mentioned above. These drawings help us in a measure to understand the important place taken by glass vessels of various forms in the researches of these 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 a long pendulous _paraison_ has only to be heated on one side near the base, when it falls over of itself to assume the well-known shape. We see also flasks, standing in water or sand baths, within which various substances are digesting; in other cases the contents are volatilising into the turban-shaped _aludels_ placed above them.[86] But in all this strange literature, which, starting from the banks of the Nile in the first centuries of our era, spread over the Byzantine 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 the transmutation of matter and the consequent preparation of gold. Glass, as I have said, was of importance chiefly as a means to that end. It was far otherwise with the writer whose work we must now examine. Theophilus, the author of the _Schedula Diversarum Artium_, was, it would seem, a monk in the monastery of Helmershausen, not far from Paderborn, in the old Saxon land. The earliest manuscript of his work probably dates from the twelfth century; it is preserved in the famous library at Wolfenbüttel. The treatise itself may 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 mediæval 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 goldsmith and a ‘skilled artificer’ in many branches of the arts. He drew his inspiration from the Byzantine East on the one hand, and on the other from the younger civilisation that was beginning to centre in the new kingdom that was growing up in and around the Isle de France. To these sources we must perhaps add the older Cluniac tradition: from Tuscan artists also he had something to learn.[87]