THE SALT DEPOSITS 217 
Diligent search has been made for other supplies of potash 
and many efforts to extract it from leucite rocks and potash- 
felspar, as well as from seaweed and sunflowers. 
Beds of potash salts have been found where large sheets 
of sea-water have been evaporated. The basin of Afar at 
the southern end of the Red Sea is geographically well suited 
for the formation of salt deposits; for it is below sea-level 
and could have been repeatedly flooded from the sea. Potash 
deposits there have been worked to some extent. 
The two most important non-German sources of potash are 
some beds left by the evaporation of an Oligocene lake near 
Mulhouse in Alsace. The deposits were developed under 
the control of the German Kali Syndicate, but after the War 
were for a time worked independently. A second field 
is in the north-east of Spain near Cardona and Suria; the 
potash minerals include carnallite, kainite, kieserite, sylvin- 
ite, and polyhalite, and rest on a thick block of salt and 
gypsum. 
Some potash has been extracted from the mud of lakes, 
such as Searles Lake in California, which receive the drainage 
from rocks rich in potash. 
At one time objection was taken in Germany to the ex- 
port of potash on the ground that it would all be wanted 
by the local farmers, Ochsenius was instructed to report on 
the available supplies; his report that one of the German 
fields could maintain an output of 3,000,000 tons per annum 
for over 600,000 years showed this fear was futile. The 
output is however limited to safeguard the water supply; 
as otherwise the waste waters would render the rivers too 
salt for drinking and would be fatal to the fish.