1) Clay 2) Terra alba 
• (v. t.) To whiten or clean with pipe clay, as a soldier`s accouterments. • (v. t.) To clear off; as, to pipeclay accounts.
Pipe'clay` transitive verb 1. To whiten or clean with pipe clay, as a soldier's accouterments. 2. To clear off; as, to pipeclay accounts. [ Slang, Eng.]
Pipeclay was old slang for to clear off.
[n] - fine white clay used in making tobacco pipes and pottery and in whitening leather
noun fine white clay used in making tobacco pipes and pottery and in whitening leather