Scientific American 15, 7.4.1860
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Indigo as good as was ever produced has been raised in South Carolina; its manufacture, however, was so fatal to the negroes that its cultivation was discontinued. It absobs oxygen in the process of manufacture so rapidly as to render the air unfit to breathe.
The power of a triangular prism to reflect the violet rays of light more than the red rays, is called its dispersive power; and it is found that flint glass, which contains a considerable proportion of the oxyd of lead, possesses this dispersive power in a much higher degree than crown glass, which contains no lead. This property has been turned to account in the construction of lenses for microscopes, telescopes, &c.