LEAD HITMAN. 611 



The height required is usually secured by means of a " shot tower" — 

 a well-known edifice to the people of certain sections of the country. 



THE MANUFACTURE OP WHITE LEAD. 



White lead is made by corroding " pig " lead. Four processes are 

 in practical commercial operation in the United States, but the 

 greater bulk of the white lead is produced by a single one known as 

 the " Old Dutch Process." 



OLD DUTCH PROCESS. 



To corrode lead by this process takes from 90 to 110 days. The 

 practice is substantially as follows: 



A layer of spent tanbark thoroughly wet down with water is 

 spread about 20 inches thick on the floor of a bin or corroding com- 

 partment. Rows of earthenware pots shaped somewhat like flower- 

 pots, about 12 inches high and 8 inches in diameter at the top and 

 tapering to about 5 inches at the bottom, are placed thereon close 

 together. In the bottom of each pot is poured about one-half pint 

 of weak acetic acid (practically vinegar). The pots are then filled 

 with wafflelike perforated disks or " buckles " of extremely pure lead 

 previously cast from molten "pig" lead. Each buckle is about 6 

 inches in diameter and three-sixteenth of an inch thick. The buckles 

 are piled flat and rest on a shoulder near the bottom of the pot which 

 prevents the metal from coming into direct contact with the acid. 

 From 10 to 14 buckles are put in each pot. 



Over the filled pots is laid a floor of planks and on these planks 

 is spread another layer of tanbark. A second layer of pots is then 

 arranged as before, and alternating layers of pots and tanbark are 

 built up until about 10 tiers, or a " stack," are in place. 



Fermentation of the tanbark soon sets in. The heat thus gener- 

 ated, the temperature of which ranges between 160° and 180° F., 

 causes the acetic acid to volatilize. Its fumes attack the lead, chang- 

 ing the metal on the surface to a thin film of acetate of lead. Car- 

 bonic acid gas, liberated by the decomposing tanbark, acts on this 

 film of acetate of lead, converting it into carbonate of lead. The 

 action of the carbonic acid gas on the acetate of lead frees acetic 

 . acid in the latter, and this freed acid attacks the metallic lead just 

 below the first film of white lead and changes more lead to acetate 

 of lead, which in turn is changed, by the process described, to car- 

 bonate of lead. Continuous attacks of acetic acid and carbonic- acid 

 gas proceed in this way until all the lead clear down to the heart of 

 the buckle is corroded into white lead. 



At the end of about four months the stack is taken down or 

 " stripped." The buckles of lead, which were blue, are found to be 

 white except for a core of metallic lead which sometimes remains 



