﻿Brown: 
  Silicious 
  skeleton 
  417 
  

  

  combustible 
  material. 
  That 
  the 
  chemical 
  composition 
  varies 
  in 
  

   different 
  species 
  is 
  certain, 
  but 
  silica 
  or 
  some 
  silicate 
  is 
  evidently 
  

   present 
  in 
  very 
  case. 
  That 
  the 
  skeleton-rods 
  of 
  Tecoma 
  are 
  highly 
  

   silicified 
  is 
  plainly 
  shown 
  from 
  an 
  examination 
  of 
  burned 
  macerated 
  

   fibers 
  before 
  and 
  after 
  treatment 
  with 
  hydrochloric, 
  nitric, 
  and 
  

   hydrofluoric 
  acid. 
  Before 
  treatment 
  with 
  acid 
  the 
  rods 
  are 
  in- 
  

   variably 
  present; 
  also, 
  after 
  treatment 
  with 
  hydrochloric 
  or 
  

   nitric 
  acid 
  they 
  are 
  present; 
  but 
  after 
  treatment 
  with 
  hydrofluoric 
  

   acid 
  they 
  are 
  invariably 
  absent. 
  

  

  Furthermore, 
  it 
  is 
  of 
  great 
  interest 
  to 
  note 
  that 
  the 
  heat 
  gener- 
  

   ated 
  by 
  an 
  alcohol 
  flame, 
  together 
  with 
  that 
  of 
  the 
  burning 
  fiber, 
  is 
  

   sufficient 
  to 
  cause 
  the 
  formation 
  of 
  glass 
  beads, 
  usually 
  at 
  the 
  

   ends 
  of 
  the 
  silicious 
  rods, 
  as 
  shown 
  in 
  Fig. 
  3, 
  E. 
  This 
  often 
  

   happens 
  when 
  the 
  calcium-rich 
  fibers 
  of 
  Tecoma 
  are 
  burned 
  and 
  

   less 
  frequently 
  in 
  calcium-poor 
  material 
  like 
  Secale. 
  These 
  

   beads 
  are 
  insoluble 
  in 
  hydrochloric, 
  nitric, 
  or 
  sulphuric 
  acid 
  and 
  

   have 
  an 
  index 
  of 
  refraction 
  of 
  1.59, 
  approaching 
  that 
  of 
  flint 
  glass. 
  

   The 
  calcium 
  is, 
  In 
  all 
  probability, 
  changed 
  to 
  lime 
  by 
  the 
  heat, 
  

   and 
  would 
  thus 
  act 
  as 
  a 
  flux 
  upon 
  any 
  silica 
  in 
  the 
  rods, 
  causing 
  

   the 
  formation 
  of 
  the 
  highly 
  refractive 
  glass 
  beads. 
  The 
  result 
  

   would 
  be 
  the 
  same 
  whether 
  the 
  rods 
  were 
  composed 
  of 
  silica, 
  such 
  

   as 
  quartz 
  or 
  opal, 
  or 
  of 
  highly 
  silicified 
  material. 
  Also, 
  the 
  same 
  

   reaction 
  to 
  hydrofluoric 
  acid 
  would 
  be 
  obtained 
  In 
  either 
  case, 
  

   since 
  either 
  silica 
  or 
  silicates 
  would 
  be 
  quickly 
  dissolved 
  by 
  this 
  

   reagent. 
  

  

  The 
  question 
  now 
  arises 
  whether 
  the 
  silica 
  in 
  the 
  secondary 
  

   thickening 
  of 
  the 
  Tecoma 
  fiber 
  is 
  actually 
  present 
  in 
  an 
  amount 
  that 
  

   would 
  be 
  necessary, 
  if 
  it 
  is 
  assumed 
  that 
  the 
  skeleton 
  rods 
  are 
  com- 
  

   posed 
  either 
  of 
  silica 
  or 
  of 
  highly 
  silicified 
  material. 
  Macerated 
  

   , 
  material 
  may 
  be 
  used 
  in 
  an 
  approximate 
  anaylsis 
  of 
  the 
  mineral 
  

   content 
  of 
  this 
  portion 
  of 
  the 
  fiber 
  wall, 
  since 
  in 
  the 
  species 
  of 
  

   Tecoma 
  examined 
  the 
  vessels, 
  ray 
  cells, 
  and 
  elements 
  other 
  than 
  

   the 
  fibers 
  have 
  thin 
  walls 
  and 
  do 
  not 
  make 
  up 
  a 
  material 
  part 
  

   of 
  a 
  macerated 
  preparation. 
  It 
  was 
  thus 
  possible 
  to 
  obtain 
  

   several 
  grams 
  of 
  material 
  made 
  up 
  in 
  large 
  part 
  of 
  the 
  secondary 
  

   thickening 
  of 
  fibers; 
  after 
  combustion*, 
  1.8 
  per 
  cent 
  (of 
  the 
  dry 
  

   weight 
  of 
  the 
  fiber) 
  of 
  mineral 
  matter 
  was 
  obtained 
  and 
  .1 
  per 
  

   cent 
  (of 
  the 
  dry 
  weight 
  of 
  the 
  fiber) 
  of 
  silica 
  or 
  silicic 
  acid. 
  Silicon 
  

  

  