﻿8 
  JOURNAL 
  OF 
  THE 
  WASHINGTON 
  ACADEMY 
  OF 
  SCIENCES 
  VOL. 
  12, 
  NO. 
  1 
  

  

  refracting 
  and 
  are 
  being 
  further 
  studied. 
  Sulphuric 
  acid 
  decomposes 
  

   the 
  mineral 
  with 
  separation 
  of 
  silica 
  and 
  formation 
  of 
  barium 
  sulphate. 
  

   An 
  analysis 
  of 
  a 
  hand-picked 
  sample 
  of 
  gillespite, 
  with 
  only 
  a 
  few 
  

   per 
  cent 
  of 
  other 
  mineral 
  present 
  gave 
  the 
  following 
  results 
  : 
  

  

  Analysis 
  of 
  gillespite 
  Ratios 
  

  

  Si02 
  50.08 
  0.831 
  4.034 
  or 
  4 
  X 
  1 
  .01 
  

  

  FeO 
  14.60 
  0.203 
  0.985 
  or 
  1 
  X 
  0.99 
  

  

  BaO 
  31.02 
  0.202 
  0.980 
  or 
  1 
  X 
  0.98 
  

  

  AI2O3 
  0.34 
  

  

  FeaOs 
  0.56 
  0.008 
  

  

  MnzOa 
  0.14 
  

  

  Insoluble 
  2.20 
  

  

  Water" 
  0.82 
  

  

  99.76 
  

   " 
  Water 
  determined 
  by 
  "ignition 
  loss" 
  corrected 
  for 
  (assumed) 
  oxidation 
  of 
  FeO 
  to 
  

   Fe203. 
  Selected 
  pure 
  fragments 
  of 
  gillespite 
  give 
  no 
  water 
  when 
  heated 
  in 
  a 
  closed 
  tube. 
  

  

  The 
  formula 
  of 
  gillespite 
  is 
  FeO.Ba0.4Si02 
  or 
  Fe"BaSi40io. 
  If 
  

   the 
  ferrous 
  iron 
  and 
  the 
  barium 
  be 
  considered 
  as 
  isomorphously 
  re- 
  

   placing 
  each 
  other, 
  then 
  the 
  formula 
  simplifies 
  to 
  (Fe",Ba)Si20r,. 
  

   There 
  is, 
  however, 
  no 
  evidence 
  for 
  such 
  isomorphous 
  replacement 
  

   and 
  as 
  the 
  ratios 
  of 
  ferrous 
  iron 
  and 
  barium 
  in 
  the 
  analysis 
  are 
  sharply 
  

   1:1, 
  the 
  formula 
  Fe'^BaSi^Oio 
  is 
  to 
  be 
  preferred. 
  

  

  The 
  presence 
  of 
  the 
  small 
  quantity 
  of 
  manganese 
  was 
  definitely 
  

   determined 
  and 
  it 
  is 
  assumed 
  to 
  be 
  present 
  in 
  the 
  strongly 
  chromatic 
  

   manganic 
  state; 
  the 
  combination 
  of 
  such 
  manganic 
  manganese 
  with 
  

   possibly 
  a 
  small 
  quantity 
  of 
  ferric 
  iron 
  yielding 
  the 
  deep 
  red 
  color 
  of 
  

   the 
  mineral. 
  Titanium 
  is 
  not 
  present. 
  

  

  There 
  does 
  not 
  seem 
  to 
  be 
  any 
  group 
  of 
  minerals 
  to 
  which 
  gillespite 
  

   is 
  closely 
  related, 
  considering 
  its 
  properties 
  and 
  chemical 
  composition. 
  

  

  ICHTHYOLOGY. 
  — 
  Notice 
  of 
  a 
  spiral 
  valve 
  in 
  the 
  Teleostean 
  fish 
  

   Argentina 
  silus, 
  with 
  a 
  discussion 
  of 
  some 
  skeletal 
  and 
  other 
  char- 
  

   acters.^ 
  William 
  C. 
  Kendall 
  and 
  Donald 
  R. 
  Crawford, 
  

   U. 
  S. 
  Bureau 
  of 
  Fisheries. 
  

  

  introduction 
  

  

  Distribution.- 
  — 
  -Argentina 
  silus 
  is 
  found 
  rather 
  infrequently 
  along 
  

   the 
  Atlantic 
  coast 
  of 
  the 
  United 
  States, 
  although 
  it 
  is 
  not 
  rare 
  off 
  the 
  

   coast 
  of 
  Norway. 
  The 
  flesh 
  is 
  edible, 
  but 
  Argentina 
  silus 
  is 
  not 
  

   taken 
  in 
  sufficient 
  quantities 
  to 
  be 
  of 
  economic 
  importance. 
  

  

  * 
  Received 
  November 
  19, 
  1921. 
  

  

  