﻿Geology 
  and 
  Mineralogy. 
  321 
  

  

  of 
  the 
  rubber 
  bulb. 
  The 
  point 
  is 
  then 
  quickly 
  cleaned 
  of 
  dross 
  

   with 
  filter 
  paper 
  and 
  is 
  passed 
  through 
  the 
  wider 
  tube 
  to 
  the 
  

   bottom 
  and 
  emptied 
  by 
  pressing 
  the 
  bulb. 
  The 
  point 
  of 
  the 
  

   tube 
  must 
  be 
  so 
  fine 
  that 
  the 
  amalgam 
  will 
  come 
  out 
  only 
  on 
  

   squeezing 
  the 
  bulb. 
  This 
  process 
  is 
  repeated 
  until 
  the 
  limb 
  

   contains 
  the 
  desired 
  quantity 
  of 
  the 
  amalgam. 
  The 
  vessel 
  is 
  

   then 
  removed 
  from 
  the 
  water 
  bath. 
  After 
  cooling, 
  the 
  amalgam 
  

   must 
  adhere 
  to 
  the 
  glass 
  and 
  must 
  show 
  a 
  clean 
  surface 
  with 
  a 
  

   metallic 
  lustre. 
  

  

  For 
  insertion 
  of 
  the 
  mercury, 
  a 
  dropping 
  tube 
  with 
  a 
  long 
  

   stem 
  will 
  be 
  found 
  convenient. 
  The 
  paste 
  may 
  be 
  poured 
  in 
  

   through 
  a 
  wide 
  tube 
  reaching 
  nearly 
  down 
  to 
  the 
  mercury 
  and 
  

   having 
  a 
  funnel-shaped 
  top. 
  If 
  the 
  paste 
  does 
  not 
  move 
  down 
  

   freely 
  it 
  may 
  be 
  pushed 
  down 
  with 
  a 
  small 
  glass 
  rod. 
  The 
  paste 
  

   and 
  the 
  amalgam 
  are 
  then 
  both 
  covered 
  with 
  the 
  zinc 
  sulphate 
  

   crystals 
  before 
  the 
  concentrated 
  zinc 
  sulphate 
  solution 
  is 
  poured 
  

   in. 
  This 
  should 
  be 
  added 
  through 
  a 
  small 
  funnel, 
  so 
  as 
  to 
  leave 
  

   the 
  neck 
  of 
  the 
  vessel 
  clean 
  and 
  dry. 
  

  

  For 
  convenience 
  and 
  security 
  in 
  handling, 
  the 
  cell 
  may 
  be 
  

   mounted 
  in 
  a 
  suitable 
  case 
  so 
  as 
  to 
  be 
  at 
  all 
  times 
  open 
  to 
  

   inspection. 
  

  

  In 
  using 
  the 
  cell, 
  sudden 
  variations 
  of 
  temperature 
  should, 
  as 
  

   far 
  as 
  possible, 
  be 
  avoided, 
  since 
  the 
  changes 
  in 
  electromotive 
  

   force 
  lag 
  behind 
  those 
  of 
  temperature. 
  

  

  II. 
  Geology 
  and 
  Mineralogy. 
  

  

  1. 
  Change 
  of 
  level 
  in 
  the 
  West 
  Indian 
  Region. 
  — 
  Mr. 
  C. 
  T. 
  

   Stimpson 
  has 
  a 
  paper 
  on 
  the 
  Distribution 
  of 
  the 
  land 
  and 
  fresh- 
  

   water 
  Mollusks 
  of 
  the 
  West 
  Indian 
  Region, 
  and 
  the 
  evidence 
  they 
  

   afford 
  with 
  regard 
  to 
  past 
  changes 
  ol 
  land 
  and 
  sea. 
  He 
  con- 
  

   cludes 
  that 
  all 
  the 
  evidence 
  of 
  the 
  terrestrial 
  and 
  fluviatile 
  mol- 
  

   luscan 
  fauna 
  of 
  this 
  region 
  indicates 
  that 
  in 
  the 
  early 
  Tertiary 
  

   period, 
  perhaps, 
  there 
  was 
  a 
  general 
  land 
  elevation 
  of 
  the 
  Greater 
  

   Antilles, 
  and 
  possibly 
  of 
  some 
  of 
  the 
  adjacent 
  area; 
  that 
  Wal- 
  

   lace's 
  theory 
  of 
  a 
  land 
  connection 
  of 
  the 
  greater 
  islands 
  is 
  correct 
  ; 
  

   that 
  during 
  some 
  part 
  of 
  this 
  time 
  a 
  landway 
  extended 
  across 
  to 
  

   the 
  continent 
  ; 
  that 
  the 
  species 
  and 
  groups 
  of 
  this 
  then 
  connected 
  

   territory 
  migrated 
  to 
  some 
  extent 
  from 
  one 
  part 
  of 
  it 
  to 
  another, 
  

   and 
  that 
  a 
  probable 
  connection 
  existed 
  over 
  the 
  Bahama 
  plateau 
  

   to 
  what 
  was 
  at 
  that 
  time 
  no 
  doubt 
  the 
  island 
  of 
  Florida. 
  

  

  Jamaica, 
  by 
  the 
  evidence 
  of 
  its 
  land 
  snails, 
  stands 
  the 
  most 
  

   isolated 
  of 
  any 
  of 
  the 
  islands; 
  Cuba 
  is 
  the 
  next 
  most 
  so, 
  while 
  

   those 
  of 
  Haiti 
  and 
  Puerto 
  Rico 
  are 
  much 
  more 
  nearly 
  related 
  to 
  

   each 
  olher 
  than 
  to 
  those 
  of 
  either 
  of 
  4.he 
  first 
  two. 
  About 
  20 
  genera 
  

   and 
  minor 
  groups 
  are 
  confined 
  to 
  or 
  have 
  their 
  metropolis 
  in 
  

   Jamaica; 
  a 
  like 
  number 
  belong 
  to 
  Cuba, 
  7 
  to 
  Haiti, 
  and 
  1 
  to 
  

   Puerto 
  Rico. 
  

  

  It 
  bears 
  directly 
  on 
  this 
  subject, 
  that 
  the 
  strait 
  between 
  Haiti 
  

   and 
  Jamaica 
  is 
  deeper 
  than 
  that 
  between 
  any 
  of 
  the 
  other 
  islands, 
  

  

  