SCIENCE IN THE INDUSTRIAL WORLD 



tion of this material facilitates the action of the acetic 

 acid upon the lead in forming the lead acetate. At the 

 same time carbonic acid, which is given off in the 

 process of fermentation, combines with the lead acetate 

 to form white lead. It takes from four to six weeks 

 for the process to be completed, but at the end of that 

 time from eighty to ninety per cent, of the metallic lead 

 will have been converted into white lead, which is washed 

 and ground into the white powder of commerce. 



Aside from the cost of the material in the manu- 

 facture of white lead for pigment there is constantly the 

 danger of poisoning during the process. White lead is 

 an insidious poison, and the colics and paralyses of 

 lead-workers have been known for ages. It is advisable, 

 therefore, for manufacturers to provide mechanical 

 means of conducting the operations of manufacturing 

 their product; and this is required by law in many 

 countries. 



The German or Austrian process of making the white 

 lead is the same in principle as that of the Dutch, but 

 in this method the heat and carbonic acid are produced 

 by ordinary combustion. Specially constructed fur- 

 naces are made in which the products of combustion are 

 made to pass over the solution of lead acetate; and as 

 carbonic acid is one of these products, a combination 

 of this substance with the lead forms the lead carbonate 

 or white lead. 



In the French process, the solution of the basic lead 

 acetate is made from the metallic lead ribbons. Into 

 this solution carbonic acid gas is passed, this gas being 

 generated either by heating limestone, which produces a 



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