In England, Kimmeridge Clay, Lias clays, London Clay and pulverized shale and slate are all employed for this purpose.
After this treatment the upper 2 or 3 in, of soil are well pulverized, and fertilizers added, usually, to prevent reintroduction of seeds of weeds, in the form of guano or chemical manures.
In the Cazo, Caldron or Hot process the pulverized silver ore is boiled in a copper-bottomed wooden vat, first with brine until the silver has been reduced by the copper, and then with quicksilver.
Amalgamation is based on the property of quicksilver to extract the silver from finely-pulverized ore and collect it in the form of an amalgam.
They are crushed to egg-size in a rock-breaker, and pulverized to pass a 40-mesh sieve in a California stamp-mill, which treats in 24 hours about 3 tons per stamp. A 10-stamp mill is fed by one rock-breaker, and discharges the liquid pulp into 10-15 wooden settling tanks, 9 by 5 by 8 ft., the settled contents of which are shovelled out and charged into the pans.
In 1791 France was pulverized into innumerable administrative atoms incapable of cohesion; and the result was that Paris became more than ever the brain and nerve-centre of France.