Important: Safety Warning
This page describes trade processes that use dangerously toxic materials such as cyanide solutions, mercury amalgams, or strong acids. These processes require training, equipment, and precautions far beyond what the text describes.
This information has been left in for historical purposes but should not be acted upon.
To Clean Pendulums
Brass pendulum bobs are often found with black stains upon them that prove very obstinate to remove. Heat the bob moderately, touch the stains with a brush dipped in nitric acid, rub with a linen rag and again heat moderately.