Page:Popular Science Monthly Volume 80.djvu/51

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PSM V80 D051 Rjukan fos saltpeter works.png

Fig. 11. Rjukan-fos Saltpeter Works. Looking down the valley. From this stream "within a few years 260,000 horse-power will be available, all to be used for nitrate manufacture."

tanks where it is neutralized with limestone, forming calcium nitrate or lime-saltpeter. The solution is evaporated and the resulting nitrate fused. It is either run in a melted condition into sheet-iron drums or into large tanks where it solidifies. The drums are sealed and are ready for shipment. The nitrate which has solidified in tanks is broken up, ground and shipped in air-tight barrels. It is guaranteed to contain 13 per cent, nitrogen, but generally runs somewhat higher. The market is of course unlimited, except as far as it is in competition with Chili saltpeter and with ammonium sulfate. It has been found possible to compete with Chili saltpeter even on the Pacific coast. The greatest difficulty which would seem to militate against the artificial product, is that it is very hygroscopic, or rather, deliquescent. This difficulty seems to be practically overcome by shipping the product in excellent wooden barrels manufactured by the works themselves. Experience and experiments have proved that the nitrate shipped in this manner keeps as long as it is practically found necessary. In many soils the presence of the lime rather than soda in the fertilizer is a distinct advantage.

Another product of the same factory is ammonium nitrate, for which there is a large market in the manufacture of explosives. For this the nitric acid is neutralized with ammonia (imported at present from England) and the solution evaporated to crystallization in vacuum pans, very similar to those used in sugar factories. The product