68 



BULLETIN 42, UNITED STATES NATIONAL MUSEUM. 



Besides the fume, the slag eye produces a dirty metallic lead, which 

 is refined and sold, and slags sufficiently poor in lead to be thrown 

 away. This operation is very fully illustrated by the following col- 

 lection made by Mr. E. B. Kirby, e. m., October, 1884. 



SCOTCH HEARTH SMELTINd. 

 Ores. 



(1) Galena, with a little blende and chert, lump ore. Short Creek Mine. (551.^9.) 



(2) Galena, showing some decomposition, with a little blende and chert Lump ore 

 (65246.) 



(3) Gelena, with a little blende and chert, ready for the hearth. Dressed ore and 

 mineral. (.'')5160.) 



Fuel. 



(1) Bituminous coal; used for the hearth and boilers. (5.5162.) 

 Analyzed by the writer it gave : 



^^j , Per cent. 

 Water ^ g^. 



Volatile matter .,T r,^ 



j4.5() 



Fixed carbon 'n 'V7 



7 



Ash (pink and white) ^-, 



100. 00 

 Sulphur o~73 



Flux. 



(1) Slaked lime, made from limestone, 6 miles south of Joplin. Used to stiffen the 



slags in the Scotch hearth so that they can be easily worked. Freshly burned it 

 contains 97 per cent. Ca O. (55163.) 



Analyzed by the writer it gave : 



As received. Calculated to quicklime. 

 Per cent. Per cent. 



Loss on ignition 30. 07 



Insoluble residue 1.52 2 16 



Oxides of iron and alumina ((FeAl)j03) 0.28 0.40 



Lime (CaO) (jg. 07 96.92 



Magnesia (MgO) 0.36 0.51 



100. 30 99. 99 



Intermediate products. 



Six samples of the first flue dust are shown. This dust is very com- 

 plex in its composition, and varies somewhat according to where it is 

 deposited; it consists of oxidation products together with unaltered 

 sulphides of lead and zinc, some quicklime, carbonaceous matter, and 

 other constituents of the charge. In some cases there has been only 

 a small amount of oxidation of the sulphides. 



(1) From half way between the hearth and the fan. (55165.) 



(2) From first dust chamber. (55164.) 



i 



