See inside Chile's ghost town where 'white gold' drew thousands of miners in the early 19th century
Miners once lived and worked in Humberstone saltpeter works. Now it's a ghost town and UNESCO World Heritage Site. Photos ...
Nature18d
The Indian Saltpetre Industry 1
THE production of potassium nitrate in India is probably a very ancient industry, and at the present time, in spite of German competition, the export still amounts to about 20,000 tons per annum.