144 J. W. Shipley — Volcanic Emanations in Alaska. 



or the free acids of sulphur. A series of vents on the 

 rim of Novarupta had considerable quantities of flowers 

 of sulphur depositing on the walls bathed by the escaping 

 gases. It was here that S0 2 and H 2 S apparently co- 

 existed. These deposits were 99% pure containing iron 

 as an impurity. - Selenium or tellurium was not detected 

 in any of the samples collected in the valley. Crystalline 

 rhombic sulphur was frequently found associated in 

 varying proportions with masses of amorphous Si0 2 . 

 The two minerals had been deposited together with a 

 little Fe 2 3 as an impurity. 



The most peculiar deposition of sulphur observed was 

 in the form of rosettes around miniature orifices adja- 

 cent to the larger vents. The rosettes were composed of 

 needle-like crystals of sulphur half an inch or more in 

 length and apparently was sulphur in the monoclinic 

 system. On attempting to collect the needles, however, 

 they crumbled to pieces which on examination proved to 

 be rhombic crystals of sulphur. The sulphur originally 

 deposited as monoclinic had been transformed into 

 rhombic crystals retaining the outward form of the mono- 

 clinic mass. 



Arsenic. — Associated with sulphur as an incrustant 

 over several of the fumarole cracks small deposits of sul- 

 phides of arsenic were discovered. The mass consisted 

 of yellow crystals of orpiment containing some reddish 

 crystals that may have been realgar or the /? variety of 

 orpiment which, according to Borodowsky, 6 is red. On 

 analysis the proportion of arsenic to fixed sulphur gave a 

 ratio corresponding to the formula As 2 S 5 but it may have 

 been that the CS 2 extraction failed to remove all of the 

 free sulphur. 



Arsenic deposits. 



Free S (soluble in CS,) 52-0% 



. Fixed S 21-0% 



As 19-6% 



Residue (insol. in Na 2 C0 3 ) 4-4% 



Volatile at 80° 1-6% 



not determined 1-4% 



100% 



Fluorides. — The presence of fluorine was indicated by 

 the etching of the glass gas-washing bottle through which 



°Chem. Abst., vol. 1, p. 1106, 1907. 



