Harena enim cum nitri flore conteritur adeo subtiliter, ut efficiatur quemadmodum farina; et aes cyprum limis crassis uti scobis facta mixta conspargitur, ut conglomeretur; deinde pilae manibus versando efficiuntur et ita conligantur, ut inarescant; aridae componuntur in urceo fictili, urcei in fornace: ita aes et ea harena ab ignis vehementia confervescendo cum coaruerint, inter se dando et accipiendo sudores a proprietatibus discedunt suisque rebus per ignis vehementiam confectis caeruleo rediguntur colore.
Sand is ground with flowers of soda to such fineness that it becomes like flour. Cyprian copper is sprinkled from rough files like fine dust so that it combines with the mixture. Then, it is rolled by hand intoballs and they are put together to dry. When dry they are collected in an earthenware jar, and the jars are put in a furnace. In this way the copper and the sand burning together owing to the vehemence of the fire dry together, and, interchanging their vapours, lose their properties; and their own character being overcome by the vehemence of the fire, they acquire a blue colour. .
final_alignments\Vitruvius_Architecture_Book_7.json