Alexandrian chemical workshop, 1st century AD.
© Science Museum / Science & Society Picture Library
Diorama providing a conjectural representation of the conditions under which chemical craftsmen might have worked in Egypt in about the first century AD. The construction is based on archaeological remains and on manuscripts of this period. An asayer can be seen using a hand balance by the workshop's furnace. Refining and testing precious metals had been practised since Babylonian times. At the back is a dye vat. There are two ancient methods of dyeing. In vat-dyeing an insoluble dyestuff is first converted chemically into a soluble form. The fabric is dipped into this. Indigo and woad are used in this way. In the other method, the textile is treated with a mordant (notably alum) then dipped in the dye.