Twelfth Annual Report of the Bureau of Science— 1913.] 



Fig. 1. A leaching vat built on the ground, but high enough so that the mud may be 

 removed by gravity after the leaching is completed. 







Fig. 2. A more developed and more progressive type of leach. A kind of cultivator 

 used in loosening the soil is also shown. 



PLATE XLVI. 



