Is Charles martin hall a ghost?

Charles Martin Hall is not a ghost. He was a real person who lived from 1863 to 1914. He is famous for inventing the Hall–Héroult process for producing aluminum, which revolutionized the use of this lightweight metal.

It's possible you might have heard something about him being associated with a ghost story or a legend, but there's no evidence to support that. If you have a specific story in mind, please share it, and I can try to help you find out more about it.