These Syriac and Arabo-Syriac manuscripts (the later sections are chiefly in Arabic) form part of the material from which the Arabs learned the arts of the Greeks. They claim for the most part to be translations 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 is, perhaps, more of local knowledge and practical experience in them than appears at first sight, or than M. Berthelot seems to allow: it was the fashion then to sail under the colours of the great men of old. Beside some scattered references to the subject in other places, we find in the thirteenth section of the second part of the British Museum manuscript a chapter devoted entirely to glass—it can hardly be earlier than the ninth century. To make glass, we are told, add ten parts of alkali to ten of sand, grill the mixture in an oven till it is ‘clean as pure wool.’ Here we have the preliminary fritting described. Heat in a crucible till the substance can be drawn out like gum, ‘then make of it what 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 method of ‘cleansing’ glass by means of manganese had doubtless been handed down from Roman times, and the ‘burnt antimony’ is probably to be interpreted as a roasted ore of cobalt. For producing other colours, mention is made of various substances, but I am unable to give any reasonable interpretation of this part; we hear of tin, lead, and borax—the preparation of a fusible enamel would seem to be implied. Finally, we are told—‘Do what is to be done, according to the will of the Lord Sabaoth!’