Ink is a combination of a coloring agent called pigment (or dye) with a liquid called a vehicle which also contains oils, resins, and solvents. Throughout history, ink has been made from many different colored juices and extracts of plants and animals as well as synthetic materials. The use of ink for writing and printing dates back to 3200 b.c., when the Egyptians used a mixture of lampblack (a fine soot produced by the incomplete combustion of oils and other carbons) suspended in vegetable gum. Both the Egyptians and the Greeks used iron oxide to make red ink from about 2800 b.c., although this was employed in marking linen rather than for writing. The ancient Chinese were making both red ink (from mercury sulfate) and black ink (from iron sulfur mixed with sumac tree sap) from 2000 b.c.; like the Egyptians, they made their ink into a solid...