[Illustration:  THE KELP HARVESTER GATHERING THE SEAWEED FROM THE PACIFIC OCEAN]

[Illustration:  Courtesy of Hercules Powder Co.

OVERHEAD SUCTION AT THE SAN DIEGO WHARF PUMPING KELP FROM THE BARGE TO
THE DIGESTION TANKS]

The tourist going through Wyoming on the Union Pacific will have to the north of him what is marked on the map as the “Leucite Hills.”  If he looks up the word in the Unabridged that he carries in his satchel he will find that leucite is a kind of lava and that it contains potash.  But he will also observe that the potash is combined with alumina and silica, which are hard to get out and useless when you get them out.  One of the lavas of the Leucite Hills, that named from its native state “Wyomingite,” gives fifty-seven per cent. of its potash in a soluble form on roasting with alunite—­but this costs too much.  The same may be said of all the potash feldspars and mica.  They are abundant enough, but until we find a way of utilizing the by-products, say the silica in cement and the aluminum as a metal, they cannot solve our problem.

Since it is so hard to get potash from the land it has been suggested that we harvest the sea.  The experts of the United States Department of Agriculture have placed high hopes in the kelp or giant seaweed which floats in great masses in the Pacific Ocean not far off from the California coast.  This is harvested with ocean reapers run by gasoline engines and brought in barges to the shore, where it may be dried and used locally as a fertilizer or burned and the potassium chloride leached out of the charcoal ashes.  But it is hard to handle the bulky, slimy seaweed cheaply enough to get out of it the small amount of potash it contains.  So efforts are now being made to get more out of the kelp than the potash.  Instead of burning the seaweed it is fermented in vats producing acetic acid (vinegar).  From the resulting liquid can be obtained lime acetate, potassium chloride, potassium iodide, acetone, ethyl acetate (used as a solvent for guncotton) and algin, a gelatin-like gum.

PRODUCTION OF POTASH IN THE UNITED STATES

_______________________________________________________

___________________
|                          |
|           1916           |           1917
Source       | Tons K_{2}O | Per cent.  | Tons K_{2}O | Per cent.
|             |  of total  |             |  of total
|             | production |             | production
____________________|_____________|____________|____________

_|____________
|             |            |             |
Mineral sources:     |             |            |             |
Natural brines    |    3,994    |    41.1    |   20,652    |    63.4
Altmite           |    1,850    |    19.0    |    2,402    |     7.3
Dust from cement  |             |            |             |
mills           |             |            |    1,621    |     5.0
Dust from blast   |             |            |             |