178 ON TEE WHITE SINTER TERRACES OE ROTO-MAHAnA. 



were referred to by Mr. Drew, the springs forming domes being 

 generally, if not always, on flat ground. 



The Author, in reply to a question from the President, stated 

 that an analysis of the sinter gave : — 



Silica 86-0 



Water and organic matter 11*5 



Sesquioxide of iron and alumina 1-31 



Lime 0-45 



Magnesia 0*4 



Alkalies 0-38 



He stated that upon a line running from Tongariro, a volcano 

 always in action, towards Mayor Island, many volcanic phenomena 

 are observed, such as mud- volcanoes and geysers, and here 

 spouting geysers are met with, although these only spout occa- 

 sionally ; and it was remarkable that, as reported in the district, 

 those geysers only spout when the wind is in the east. He had 

 found by experiment that chloride of sodium does exert some solvent 

 action upon the silica of the sinter ; but nevertheless the notion of 

 the re-solution of the silica in the geyser-pipe was put forward by 

 him merely as a suggestion. The rock forming the hill in which 

 the geyser rises is rhyolitic ; and the who'e country is covered with 

 pumice. 



