Page:Popular Science Monthly Volume 91.djvu/341

 Potash from California Sea Kelp

Subterranean reapers harvest the product

��The harvester waiting for the tide to come in before it con- tinues its un- dersea kelp-cut- ting operations

���THE potash problem has been successfully solved. Our supply of raw material for its manu- facture costs little and is practically inex- haustible. Near San Diego, California, un- dersea reapers are harvesting kelp, from which potash equal to about three times our annual importation from Germany previous to the war, is made by one concern; a second plant of about equal capacity has been established in the same vicinity, and a smaller plant installed by the Government is in operation. Just now, the manufacture of munitions requires all that can be pro- duced, but we can obtain all that is re- quired for ourselves and our allies.

The reaper cuts the weed four feet below the water surface when empty and six feet when loaded, the depth having been

��made a Government regulation for conserv- ing the supply. Each of the three boats in the Hercules fleet takes about five hun- dred tons every working day, which means practically every day in California. The cut kelp is carried aboard the harvester on a continuous belt elevator to a mill, where it is crushed. The resultant sticky, gelatinous mass, deposited in the storage hopper, contains about eighty per cent water. This is pumped through a six-inch pipe. As soon as a capacity load is ready it is transferred by pumps to barges and thence into digestive tanks on the wharf, each of 50,000 gallons capacity. Subsequent processes deal with evaporation.

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