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pans. The finished nitrate is shoveled from the bateas into cars, drawn to the deposit, or cancha, and there after drying for several days is bagged ready for shipment. Shipment in bulk is impracticable because the nitrate so readily absorbs water. Even when shipped in sacks it sometimes becomes caked in the holds of ships and has to be taken out with picks.

From the agua vieja, iodine is extracted by a simple process of precipitation with chemicals (mainly sodium sulphites). It figures only as an important by-product of the industry, for the "iodine trust" makes an annual allotment to each establishment, commonly less than what could be made in a month, if there were no restrictions on production.

The only other important step in the refining of nitrate is the clearing and recharging of the boiling tanks. First, fresh water is run through to take out what it will of the remaining nitrate, this water being used subsequently, with aqua vieja, in the boiling process, for the more nitrate in solution at the outset the easier it is to get a saturated caldo. After the washing is over, a trap in the bottom of the tank is opened and the waste, or ripio, is removed. This process is the most bothersome in the industry, because for each charge of 70 tons of caliche, 50 tons or more of ripio must be removed. It is very hard on the men who work in the steaming hot tanks, and the disposal of the waste after it is removed, not uncommonly 1,000 to 3.000 tons a day, soon comes to be a problem. None of the operators succeed in getting much more than 75 per cent, of the nitrate originally in the caliche, hence ripio commonly contains 4 to 10 per cent, of nitrate, and the great piles containing