2 On the Occurrence of Silver in Volcanic Ash. [Jan. 6, 



(strongly attracted, and easily removed by the end of a magnetic 

 needle), and thin scales of deep red specular iron oxide were easily 

 distinguished. 



The ash on being strongly heated before the blowpipe, or even in 

 considerable quantity in a small platinum crucible over the blast 

 lamp, turned dark red-brown, and fused to a nearly black slag. 



On being boiled in its original state with water it gave up 0*21 per 

 cent, of soluble matter. The solution gave very distinctly the reactions 

 of chlorine, a sulphate, and sodium ; in a less marked degree the 

 reactions of potassium. On boiling with strong hydrochloric acid, 

 6'94 per cent, was dissolved, in addition to that already extracted by 

 water ; the acid solution was deeply coloured by iron. 



The specific gravity of the ash was found = 2'624 at 18° C. as 

 compared with water at the same temperature. 



An analysis of the material taken as a whole, i.e., without any 

 previous mechanical separation of its consistent minerals, and without 

 previous digestion with water or acid, but dried at 100° C, gave the 

 following results : — 



56-89 

 trace 

 1972 



4- 06 

 3-65 



trace 

 1-91 



5- 87 

 5-14 

 1-96 



trace 



5? 

 ?» 

 5) 



0-62 

 99-82 



Silver was first noticed after fusing* as usual with mixed sodium 

 and potassium carbonates, and dissolving in excess of hydrochloric 

 acid, on the addition of sulphuretted hydrogen to the solution, which 

 had been freed from silica ; the sulphur thrown down by ferric chloride 

 present was observed to be distinctly brown, and on being filtered out 

 and carefully burned off before the blowpipe it left a minute bead of 

 metallic silver. All the reagents and vessels used were scrupulously 

 examined, but the silver could not be traced to any of them. It was- 



Si0 2 . 



Ti0 2 



A1 2 3 



Fe 2 3 



Feb. 



MnO 



MgO 



CaO. 



Na 2 



K 0. 



Li 2 0. 



Ag.. 



CI . . 



S0 4 . 



H 2 



