288 ANNUAL REPORT SMITUSONIAN INSTITUTION, 1913. 



a more elaborate spectroscopic equipment would not help the matter. 

 Moreover, the gases are much altered or are in process of active 

 alteration before any opportunity for identification is offered, and 

 no estimate of the relative quantity of the various participating 

 gases is possible by this means. Inferences from the chemical study 

 of gases which have been burned by contact with the air while still 

 hot and inferences from the spectroscopic study of the gases while 

 burning therefore suffer alike from limitations of principle and 

 should be resorted to only when the difficulty of collecting unaltered 

 gas is insuperable. 



These reasons may serve to show why this somewhat elaborate 

 effort was made to collect unaltered gases for laboratory study and 

 why Ave are inclined to give greater weight to the results obtained 

 from the study of such gases than to many of the earlier studies ^ of 

 volcanic emanations, in which the gases had become altered through 

 contact with the air or otherwise. 



The domes from which these gases were collected were built up by 

 the lava itself on the floor of the crater (Halemaumau) and were 

 both chemically and physically ideal gas collectors, being lined with 

 fresh splashes of liquid lava of the same temperature and chemical 

 composition as that from which the gas had just emerged. They 

 formed at the level of the lava lake and, as could be plainly seen 

 after the collapse of the domes, were directly connected with the 

 lake by channels of liquid lava just below the surface crust. The 

 collapse of the entire channel leading to the May dome is shown in 

 plate 8, figure 1, in which an arrow (f) has been placed to indicate 

 the position where the dome stood. The May dome was under con- 

 stant observation for several days and a considerable portion of the 

 night immediately previous to the collection, during which time 

 (here was no cessation of the lava fountain spouting within the dome 

 nor of the flames of the burning gases as they escaped through its 

 cracks. Furthermore, as the larger bubbles rose and burst from the 

 liquid lava within the dome, the jar could be felt on the floor where 

 the collectors stood and the splash could be plainly seen through the 

 cracks. 



ANALYSES OF THE GASES COLLECTED IN MAY, 1912. 



The following analyses were made of the fixed gases collected in 

 glass tubes on May 28, 1912, in the manner above described. The 

 statement is given in parts by volume. The tubes were nimibered 

 from 1 to 20 in the order in which the gases entered from the vol-eano. 

 An the tubes contained condensed water (the fii'st>— pi. 8," fig. 2, 

 containing nearly 100 cu. cm.), of whi<;h analyses will be found- on 

 page 292. .... 



' E. g., Wm. Libbey : Amer. Jwrn. Scl. (3), v(rt." 47, 1«94, p. 371. 



