72 



BUNSEN ON THE FORMATION OF 



much in the fumaroles of the lava streams that it can no longer 

 be detected in the gases, and scarcely in the condensed vapours. 

 The composition of the solid and liquid products of the fuma- 

 roles in the newly-erupted crater of Hecla in 1845, and that of 

 the lava stream which flowed from the lowest crater, correspond 

 perfectly with this fact. The moist gravel surrounding the 

 melted masses of sulphur in the interior of the uppermost and 

 largest crater had the following composition ; — 



With the exception of the ammoniacal salts derived from the 

 atmosphere, these are the same products which may be arti- 

 ficially obtained by the humid reaction of the sulphurous and 

 hydrochloric acids present in the crater fumaroles and the rock 

 of the crater. On the other hand, the only incrustation of salt 

 scantily spread over the bottom of the highest crater, and which, 

 from the unaltered condition of the rock upon w^hich it w^as de- 

 posited, could only have been formed by sublimation, possessed 

 an entirely different composition. Such an incrustation consisted 

 of— 



99-40 



