184 BULLETIN 42, UNITED STATES NATIONAL MUSEUM. 



Fuel. 



(1) Coal slack. (55432.) 



(2) Coke, manufactured from coal slack iu beehive ovens. (55424.) 



(3) Crushed coke and coal slack, two- thirds coke and one third slack; used to reduce 

 the zinc from the ore in the retorts. (55425 ) 



Charge. 



(1) Eetort charge, used in upper two rows of retorts of the Belgian furnace ; con- 

 sists of roasted ore, blue powder, scrapings from condensers, coke, and slack. 

 (55433.) 



(2) Retort charge, used in lower rows of retorts of the Belgian furnace ; consists 

 of roasted ore, coke, and slack. (55438.) 



Product. 



(1) Spelter or metallic zinc. (5.5435.) 



(2) Spelter or metallic zinc, showing fracture. (55436.) 



(3) Blue powder, a mixture of oxide and metallic zinc, resulting from imperfect 

 condensation. (55437.) 



(4) Residue, remaining in the lower retorts of the Belgian furnace after the ex- 

 traction of the zinc. (55434.) 



(5) Flue dust, consisting largely of oxide of zinc. From the reheating chambers of 

 the gas furnace. (55426.) 



(6) Flue dust, containing oxide of zinc from the flues of the roaster. (55427.) 



(7) Slag accretion, formed in the bottom of the gas furnace. (55431.) 



Accessories. 



(1) Clay, a mixture for manufacturing retorts. (.55423.) 



(2) Retort, in use one week. (55428.) 



(3) Retort, iu use one month. (55429.) 



(4) Retort, with accretions on bottom, in use two months. (55430.) 



PASSAIC ZINC WORKS. 



These works are situated at La Fayette, near Jersey City, New Jersey. 

 They were started in 1854, when faruaces for the production of oxide 

 of zinc from the Frauklinite ores were built. In 1^75 Belgian furnaces 

 for the production of spelter from the silicate and carbonate ores were 

 added, and in 1884 a shaft furnace for smelting spiegeleisen from the 

 residues from the oxide furnaces containing iron and manganese was 

 added. 



The ores used are mined at Sterling Hill, Ogdensburgh, and Mine 

 Hill, Franklin, Sussex County, New Jersey, and are divided into silicate 

 and carbonate ores, and Franklinite ores. The former are used for the 

 production of spelter, but the latter can not be, since the silicate of 

 manganese formed from the manganese in the ore is very destructive 

 to the retorts on account of its easy fusibility. The Franklinite ore is 

 very complex, containing Frauklinite, zincite, willemite, and rhodonite, 

 in varying proportions, in a gangue of calcite. 



The spelter furnaces are built in three blocks of four each, eight 

 large, and four small. The large furnaces contain seven rows of retorts 



