188 



ART. 3. B. KOTÔ : 



the writer has in mind the whitish glassy substance, consisting of 

 aggregation of bubbles, which are formed on the surface of magma 

 when coming in contact with the air by violent agitation of liquid 

 lava within the mouth of the vent. The lava-froth,^^ which is a 

 product of the Strombolian stage of activity and new to science, 

 was projected into the atmosphere and fell on land and the sur- 

 rounding sea. It is found on both sides of Sakura-jima, typical 

 specimens are seen scattered abundantly on the west with its kindred 

 ' spongy thread-lace glass scoria.' 



The forms are variable (Text-fig. 41) ; some being roughly 

 flat-conoidal, and sometimes pyramidal, but most of them are 

 irregularly rounded and always flat ; and the body is traversed 



Fig. 41. — Varicms forms of lava scums. Natural size. 

 Loc. : Yokoyama. 



1) A lava foam or froth, thoiigh different in kind, was noted in a retient paper by 

 'Tagger, Jr. (see ante, p. 93, footnote 3) as a product of ' gas-impelled and gas-heated fountains as 

 the initial maniffistation of a rising lava column.' 



