Query: in what year did Banks  negotiate between the king and the East india company for 700 tons of saltpetre?
Context: Outstanding debts were also agreed and the company permitted to export 250 tons of saltpetre. Again in 1673, Banks successfully negotiated another contract for 700 tons of saltpetre at £37,000 between the king and the company. So urgent was the need to supply the armed forces in the United Kingdom, America and elsewhere that the authorities sometimes turned a blind eye on the untaxed sales.