218 Professor Conneirs Analysis of the 



odour, arising probably from traces of organic matter de- 

 rived from the surfaces on which it had fallen, although the 

 minute portions of vegetable matter observed in it, had been 

 removed before examination as much as possible. Water took 

 up directly, scarcely any thing from it. Previous to analysis, 

 the magnetic particles were also removed, as far as possible ; 

 but they were insignificant in amount. 



Acids, whether the muriatic, or the nitro-muriatic, had 

 little action on it even when the digestion was carried on for 

 some time, and occasionally aided by heat. Little seemed 

 taken up but some iron ; and the powder did not gelatinize, 

 and shewed little trace of having been acted on. 



Recourse was therefore had to carbonate of soda for its 

 decomposition ; and as the quantity of the powder at my com- 

 mand was very small, I was obliged to conduct my analysis 

 on a very small scale. 



Five grains of the ashes reduced to impalpable powder by 

 trituration and suspension in water, were fused with car- 

 bonate of soda, and the analysis then conducted according to 

 the ordinary methods for the analysis of siliceous minerals. 



A farther quantity of 3*28 grains of the ashes in impalpa- 

 ble powder was first ignited, to determine the amount of 

 moisture and other volatile matter, and subsequently decom- 

 posed by hydrofluoric acid, to ascertain the amount of any 

 alkalies which might be present. 



The result of the analysis was as follows, in 100 parts. 



99-17 

 A comparison of this result with the analysis of volcanic 

 ashes from other craters shews a general correspondence 

 in the constitution of these matters ; the principal difference 

 being that the Hecla dust was less acted on by acids than 

 in other instances. We may of course expect some variation 



