JOPLIJ^ CITY WHITE LEAD WORKS. 393 



which flows off through the grooves in the iron hearth, and is finally caught in 

 appropriate vessels. 



The smelters at the white lead works are the same as at other places with 

 one exception. Here comes the patented process. The furnace chimneys are so 

 built that they all lead into a very large sheet iron pipe about three feet in diame- 

 ter. Everything that passes up the chimney is conducted into this large pipe, 

 which is about 200 feet long. At the other extremity of this piping is a large 

 brick building technically called the " blue room." This building is about 100 

 feet long and 50 feet wide. It is two stories high, the upper story being about 

 35 feet while the lower one is but 12. In the upper story, hanging vertically, 

 .are 772 cylindrical woolen bags about fifteen inches in diameter and 32 feet 

 long. In the lower story, running the entire length of the building, are four 

 rows of " hoppers," so called from their resemblance to grain hoppers in flouring 

 mills. The top of each ' ' hopper " is about ten feet square, and is fastened to 

 the under side of the second floor. The woolen bags in the second story open 

 directly into these hoppers, the bottoms of which are opened and closed at pleas- 

 ure by appropriate slides. All of the condensed vapors, mixed with a good deal 

 -of soot, having traversed the large pipe are caught by the woolen bags from which 

 it falls directly into the " hoppers " below. After a sufficient amount has been 

 ■collected — which requires about two weeks time — the slides at the bottom are 

 drawn and the mass runs out upon the floor. This mixture is as fine as flour. It 

 •consists mostly of soot and lead sulphate ; a small per cent is lead carbonate. 

 The black soot gives the whole mass a blue color, hence the name "blue room." 

 From this room it is taken to the slag furnaces where it is mixed with slag from 

 the smelting furnaces and again subjected to an intense heat. Fluor spar {cal- 

 cium fluoride) is from time to time added as a flux, the slag being a basic silicate. 



The flues of the slag furnaces lead into a small brick chamber, the walls of 

 which are six feet thick. On account of the great heat in this chamber its walls 

 are lined with fire- brick. From it the vapors are forced through long pipes simi- 

 lar to the one which connects the smelting furnaces with the " blue room." 

 From these pipes it is led into a large building called the "whiting room." This 

 building is arranged very similarly to the "blue room" excepting that there are 

 commodious arrangements for catching the white lead when it is run out from 

 the " hoppers." The first impression upon entering this room is that one is in a 

 large flouring mill ; everything seems to be covered with flour. From this room 

 the white lead is packed for shipment. The whole scheme is a grand one. 

 Chemically, there is nothing new about it; mechanically, it is entirely novel. 



In the process of smelting a portion of the metallic lead is vaporized. Sub- 

 sequently this vapor is oxydized, and, being in contact with so much sulphurous 

 oxide, the heat being very great, lead sulphite is formed which is soon oxydized 

 into sulphate. In the slag furnace the whole is again reduced to metallic lead, 

 but, on account of the superior heat of this furnace — the fire being made from 

 coke — the greater portion is again vaporized and oxydized. The temperature is 

 so high that the formation, or even the existence, of the carbonate is impossible, 



