﻿[9] 
  ON 
  DEEP-SEA 
  DEPOSITS. 
  7G7 
  

  

  portion, 
  and 
  the 
  process 
  is, 
  we 
  think, 
  sufficiently 
  accurate, 
  for, 
  owing 
  

   to 
  the 
  sorting 
  of 
  the 
  elements 
  which 
  goes 
  on 
  during 
  collection 
  and 
  car- 
  

   riage, 
  no 
  two 
  samples 
  from 
  the 
  same 
  station 
  give 
  exactly 
  the 
  same 
  per- 
  

   centage. 
  The 
  number 
  which 
  follows 
  the 
  words 
  " 
  carbonate 
  of 
  calcium 
  " 
  

   indicates 
  the 
  percentage 
  of 
  0aCO 
  3 
  ; 
  we 
  then 
  give 
  the 
  general 
  designa- 
  

   tions 
  of 
  the 
  principal 
  calcareous 
  organisms 
  in 
  the 
  deposit. 
  

  

  The 
  part 
  insoluble 
  in 
  the 
  hydrochloric 
  acid, 
  after 
  the 
  determination 
  

   of 
  the 
  carbonic 
  acid, 
  is 
  designated 
  in 
  our 
  descriptions 
  "residue." 
  The 
  

   number 
  placed 
  after 
  this 
  word 
  indicates 
  its 
  percentage 
  in 
  the 
  deposit; 
  

   then 
  follow 
  the 
  color 
  and 
  principal 
  physical 
  properties. 
  This 
  residue 
  

   is 
  washed 
  and 
  submitted 
  to 
  decantatious, 
  which 
  separate 
  the 
  several 
  

   constituents 
  according 
  to 
  their 
  density; 
  these 
  form 
  three 
  groups, 
  (1) 
  

   minerals, 
  (2) 
  siliceous 
  orgauisms, 
  (3) 
  fine 
  washings. 
  

  

  1. 
  Minerals. 
  — 
  The 
  number 
  within 
  brackets 
  indicates 
  the 
  percentage 
  

   of 
  particular 
  minerals 
  and 
  fragments 
  of 
  rocks. 
  This 
  number 
  is 
  the 
  re- 
  

   sult 
  of 
  an 
  approximate 
  evaluation, 
  of 
  which 
  we 
  will 
  give 
  the 
  basis 
  in 
  

   our 
  report. 
  As 
  it 
  is 
  important 
  to 
  determine 
  the 
  dimensions 
  of 
  the 
  

   grains 
  of 
  minerals 
  which 
  constitute 
  the 
  deposit, 
  we 
  give, 
  after 
  the 
  con- 
  

   traction 
  m. 
  di., 
  their 
  mean 
  diameter 
  in 
  millimeters. 
  We 
  give 
  next 
  the 
  

   form 
  of 
  the 
  grains, 
  if 
  they 
  are 
  rounded 
  or 
  angular, 
  &c. 
  ; 
  then 
  the 
  

   enumeration 
  of 
  the 
  species 
  of 
  minerals 
  and 
  rocks. 
  In 
  this 
  enumera- 
  

   tion 
  we 
  have 
  placed 
  the 
  minerals 
  in 
  the 
  order 
  of 
  the 
  importance 
  of 
  the 
  

   role 
  which 
  they 
  play 
  in 
  the 
  deposit. 
  The 
  specific 
  determinations 
  have 
  

   been 
  made 
  with 
  the 
  mineralogical 
  microscope 
  in 
  parallel 
  or 
  convergent 
  

   polarized 
  light. 
  

  

  2. 
  Siliceous 
  organisms. 
  — 
  The 
  number 
  between 
  brackets 
  indicates 
  

   the 
  percentage 
  of 
  siliceous 
  organic 
  remains 
  ; 
  we 
  obtain 
  it 
  in 
  the 
  same 
  

   manner 
  as 
  that 
  placed 
  after 
  the 
  word 
  "minerals." 
  The 
  siliceous 
  organ- 
  

   isms 
  and 
  their 
  fragments 
  are 
  examined 
  with 
  the 
  microscope 
  and 
  deter- 
  

   mined. 
  We 
  have 
  also 
  placed 
  under 
  this 
  heading 
  the 
  Glauconitic 
  casts 
  

   of 
  the 
  Foraminifera 
  and 
  other 
  calcareous 
  organisms. 
  

  

  3. 
  Fine 
  washings. 
  — 
  We 
  designate 
  by 
  this 
  name 
  the 
  particles 
  which, 
  

   resting 
  in 
  suspension, 
  pass 
  with 
  the 
  tirst 
  decantation. 
  They 
  are 
  about 
  

   0.04 
  mm 
  or 
  less 
  in 
  diameter. 
  We 
  have 
  been 
  unable 
  to 
  arrange 
  this 
  mi- 
  

   croscopic 
  matter 
  under 
  the 
  category 
  of 
  minerals, 
  for,, 
  owing 
  to 
  its 
  minute 
  

   and 
  fragmentary 
  nature, 
  it 
  is 
  impossible 
  to 
  determine 
  the 
  species. 
  We 
  

   have 
  always 
  found 
  that 
  the 
  fine 
  washings 
  increase 
  in 
  quantity 
  as 
  the 
  

   deposit 
  passes 
  to 
  a 
  clay, 
  and 
  it 
  is 
  from 
  this 
  point 
  of 
  view 
  that 
  the 
  sub- 
  

   division 
  has 
  its 
  raison 
  d'etre. 
  We 
  often 
  designate 
  the 
  lightest 
  particles 
  

   by 
  the 
  name 
  argillaceous 
  matter, 
  but 
  usually 
  there 
  are 
  associated 
  with 
  

   this 
  very 
  small 
  particles 
  of 
  indeterminable 
  minerals 
  and 
  fragments 
  of 
  

   siliceous 
  organisms. 
  The 
  number 
  within 
  brackets 
  which 
  follows 
  the 
  

   words 
  "fine 
  washings" 
  is 
  obtained 
  in 
  the 
  same 
  manner 
  as 
  those 
  placed 
  

   after 
  "minerals" 
  and 
  "siliceous 
  organisms." 
  

  

  These 
  few 
  words 
  will 
  suffice 
  to 
  render 
  the 
  descriptions 
  intelligible. 
  

   Greater 
  details 
  will 
  be 
  given, 
  as 
  already 
  stated 
  in 
  the 
  Challenger 
  report. 
  

  

  