launder vs sluice box

launder

noun
  • A trough used by miners to receive powdered ore from the box where it is beaten, or for carrying water to the stamps, or other apparatus for comminuting (sorting) the ore. 

  • A gutter (for rainwater). 

  • A trough or channel carrying water to the wheel of a watermill. 

verb
  • To disguise the source of (ill-gotten wealth) by various means. 

  • To wash; to wash, and to smooth with a flatiron or mangle; to wash and iron. 

sluice box

noun
  • A box with riffles along the bottom, used to trap heavier gold particles as water washes them and the other material along the box. 

How often have the words launder and sluice box occurred in a corpus of books? (source: Google Ngram Viewer )