National Geographic : 1922 Sep
228 THE NATIONAL GEOGRAPHIC MAGAZINE A NITRATE PLANT OF NORTHERN CHILE At the side of the plant are big hoppers into which caliche, the crude nitrate rock from the pampa, is unloaded. From the hoppers the rock is fed into the crushers, and, after being broken into small pieces, is thrown into iron vats and boiled until the saltpeter can be filtered. CRYSTALLIZATION VATS, NITRATE PLANT The hot brine, brought down from the boiling-tanks through the trough in the foreground, is cooled and crystallized in these vats. The nitrate, dug out of the vats a few hours ago, is now draining on the ledge. Most of Chile's nitrate comes to the United States to be used as fertilizer.