﻿488 
  F. 
  A. 
  Perret 
  — 
  Volcanic 
  Research 
  at 
  Kilauea. 
  

  

  22. 
  "Pressure 
  casting" 
  of 
  trees. 
  

  

  23. 
  Permanence 
  of 
  crater 
  and 
  conduit 
  walls, 
  floating 
  islands, 
  

   etc., 
  due 
  to 
  slowly 
  consolidated 
  lava 
  having 
  higher 
  fusing 
  

   point 
  by 
  reason 
  of 
  crystallization. 
  

  

  24. 
  Temperature 
  of 
  modern 
  lake 
  shown 
  to 
  be 
  from 
  1050° 
  to 
  

   1175° 
  C— 
  possibly 
  from 
  1000° 
  to 
  1200°. 
  

  

  25. 
  Appearance 
  of 
  white 
  heat 
  often 
  due 
  to 
  absorption 
  of 
  

   yellow 
  rays 
  by 
  transparent 
  burnt 
  gases. 
  

  

  26. 
  Thermo-electric 
  element 
  preferable 
  to 
  electric 
  resistance 
  

   thermometer 
  for 
  field 
  work. 
  

  

  27. 
  Chemical 
  and 
  physical 
  characteristics 
  of 
  fountain 
  lava 
  

   collected 
  directly. 
  

  

  Posillipo, 
  Naples, 
  August, 
  1913. 
  

  

  