Greg Walker, age 14, of Baton Rouge, La., for his question:

IS THERE AN ARTIFICIAL INDIGO?

Indigo is a deep blue dye that is often extracted from plants, including the indigo plant. However, most indigo dye today is chemically produced and is therefore artificial.

A German chemist named Adolf von Baeyer in 1880 was the first to make artificial indigo. He used coal tar.

The first commercial process for manufacturing artificial indigo was developed and marketed in 1897. By 1907, it had almost completely replaced natural indigo as a dye. The artificial aye has a more even color than the natural indigo and it is also a lot cheaper.

At one time the growing of indigo plants was an important industry in Bengal, India. It was also grown in China, Java, Mexico and Central America.

Blue indigo dye used to be made by soaking or cooking the indigo blue from the plant.