Constituents of Dust and Soot from various Sources. 101 



Spectrum 2. — Flue dust from basic iron furnace. Samuelson's 

 No. 9— 



Na, K, Ca, Fe, Rb, Pb, Mn ; 



traces of Cu, Ag, Ni, Tl, Ga, In, Cs, Sr. 



,, 3. — Flue dust, Gjers, Mills, and Co. — 



Na, K, Ca, Fe, Rb, Pb, Mn ; 

 traces of Cu, Ag, Ni, K, Ga, In. 



Plate 354. 



Spectrum 4. — Flue dust, Gjers, Mills, and Co. — 



Fe, Ca, Cu, Mn, Na, K, Pb, Rb ; 

 traces of Ni, Tl, Ag. 



Plate 325. 1. — Flue dust from Nicholson's copper smelting works, 

 Hunslet, Leeds — 



Na, Cu, Pb, Tl, Ag, In, Fe, K, 



Ca, Ga, Rb. 



Plate 312. — Iron pyrites from coal — ■ 



Fe, Cu, Tl, Pb, Ag, and possibly a trace of gallium. 



Volcanic Dust. 



Specimens received from Professor J. P. O'Reilly. 



Plate 311. — Te Arilci. After complete solution of the substance the 

 heavy metals were precipitated with ammonia and the filtrate with 

 ammonium oxalate, after which the solution containing magnesia 

 and the alkalies was examined. 

 Spectrum 1. — The ammonia precipitate — 



Fe, Ca, Pb, Na, K trace, Ga trace, Cu trace. 

 , 5 2. — The ammonium oxalate precipitate — 



Ca, Sr, Mn, traces of Na, K, Pb, Fe, and Ag. 



„ 3. — Magnesia and the alkalies — 



Na, K, MgO, Mn, Rb, Cu; 

 Ni the merest trace. 



Taurwnga. 



Plate 311. 



Spectrum 4. — The ammonia precipitate — 



The constituents are similar to No. 1. 

 ,, 5. — Ammonium oxalate precipitate. 



Similar to No. 2. 

 ,, 6. — Magnesia and the alkalies — 



Similar to No. 3. 



