Page "Henry David Thoreau" Paragraph 15

Thoreau returned to Concord and worked in his family's pencil factory, which he continued to do for most of his adult life.

He rediscovered the process to make a good pencil out of inferior graphite by using clay as the binder ; this invention improved upon graphite found in New Hampshire and bought in 1821 by relative Charles Dunbar.

( The process of mixing graphite and clay, known as the Conté process, was patented by Nicolas-Jacques Conté in 1795 ).

His other source had been Tantiusques, an Indian operated mine in Sturbridge, Massachusetts.

Later, Thoreau converted the factory to produce plumbago ( graphite ), which was used to ink typesetting machines.