658 geology of samoa and the eruptions in savaii, 



5. Gases Evolved and General Observations. 



The great vapour clouds formed where the lava runs into the 

 sea contain sulphur gases as well as the salt already referred to. 

 The rains from these vapours have a very injurious effect on the 

 cocoanut trees at Matauto and Safune. The immense steam- 

 clouds rising from the crater and from a venthole one-half or 

 three-quariers of a mile north-east of the crater are highly charged 

 with noxious gases. One can easily detect by the smell sulphur 

 dioxide, sulphuretted hydrogen, and hydrochloric acid. The rain 

 which falls south-west of the crater (the prevailing winds being 

 from the north-east) has killed all vegetation for miles around. 

 At Olenono, three or four miles west of the crater, not only have 

 the plantation trees and all the forest been killed by the rain, 

 but the rain-water is in reality dilute sulphurous acid, which 

 rusts galvanised iron rapidly, and curdles condensed milk. 

 Patches of forest near Olenono, which were still green in the 

 middle of June, were quite leafless by the end of the month. It 

 appears that the forest destruction by poisoning has taken place 

 wholly in the months of May, June, and July of the present year. 

 Hence it may be concluded that the evolution of noxious gases 

 must have greatly increased during these months, and that the 

 volcano is becoming more solfataric. 



Carbonic acid is probably also evolved, but no definite proof 

 was noticed. 



Speaking generally, the activity has been weakening since 

 March last. After the outbreak in August, 1905, until Decem- 

 ber, 1905, violent explosions are said to have taken place fre- 

 quently in the crater, hurling stones and lava hundreds of yards 

 into the air, and over a radius exceeding half-a-mile. The lava 

 frequently overflowed at the top of the crater rim. Mr. von der 

 Heide, of Olenono, informs me that since then the lava has been 

 gradually sinking in the crater, and explosive action has practi- 

 cally ceased. Now the lava-level is 200 feet beneath the rim. 

 A steady but gradually diminishing stream has, since March, 

 been flowing to the sea through the lava-tunnel. Probably so 

 much material is now exuded that pressure within is relieved, 



