Eddie Walden, age 14, of Chester, Penn., for his question:

DOES THE INDIGO PLANT HAVE ANY VALUE?

Indigo is a deep blue dye used to color cotton and wool. In past times, this dye was taken from the indigo plant, a member of the pea family that now grows chiefly in India. Large amounts of indigo began to be produced in South Carolina in the 1740s and in Georgia during the 1750s, but the industry disappeared after the Civil War. Manufacturers started to make synthetic indigo and the indigo plantations were no longer necessary.

So the indigo plant has no great commercial value today.

Synthetic indigo is made from aniline, a coal tar product. The process was discovered by Sir William Perkin 1856 and was first applied in the dye industry by German chemists in 1897. It opened up a whole new field in the making of synthetic dyes.

Indigo is a vat color, so called because it does not dissolve in water. After a cotton or wollen fabric has been dyed, it is removed from the vat and exposed to air to oxidize it a deep blue which is resistant to removal by water.