﻿CLAYS 
  OF 
  IS'EW 
  YOKK 
  531 
  

  

  more 
  or 
  less 
  refractory 
  character 
  of 
  the 
  clay. 
  The 
  fusion 
  is 
  trans- 
  

   ferred 
  to 
  a 
  porcelain 
  Qasserole, 
  dissolved 
  in 
  water, 
  and 
  the 
  solution 
  

   acidified 
  with 
  hydrochloric 
  acid; 
  the 
  solution 
  is 
  then 
  evaporated 
  to 
  

   dryness, 
  and 
  the 
  casserole 
  with 
  its 
  contents 
  placed 
  in 
  a 
  drying 
  oven 
  

   at 
  105° 
  to 
  110° 
  C, 
  and 
  allowed 
  to 
  remain 
  till 
  all 
  the 
  hydrochloric 
  

   acid 
  is 
  expelled. 
  The 
  silica 
  present 
  is 
  thus 
  rendered 
  insoluble. 
  

   Hydixx^hloric 
  acid 
  and 
  water 
  are 
  now 
  added 
  ; 
  the 
  casserole 
  is 
  wanned 
  

   for 
  a 
  few 
  minutes 
  on 
  the 
  water 
  bath 
  and 
  the 
  solution 
  filtered, 
  the 
  

   silica 
  being 
  washed 
  with 
  hot 
  water 
  till 
  the 
  washings 
  are 
  free 
  from 
  

   chlorin. 
  The 
  silica 
  is 
  then 
  ignited 
  and 
  weighed, 
  and, 
  as 
  it 
  is 
  likely 
  

   to 
  retain 
  small 
  quantities 
  of 
  alumina, 
  it 
  is 
  treated 
  mth 
  hydrofluoric 
  

   and 
  sidfuric 
  acids 
  and 
  heated, 
  the 
  silica 
  being 
  thus 
  volatilized 
  as 
  

   silicon 
  tetra-fluorid. 
  The 
  residue 
  from 
  this 
  treatmemt 
  is 
  weighed, 
  

   and 
  its 
  Tveight 
  added 
  to 
  that 
  of 
  the 
  alumina 
  subsequently 
  found. 
  

  

  If 
  the 
  original 
  fusion 
  of 
  the 
  clay 
  showed 
  little 
  or 
  no 
  green 
  color, 
  

   the 
  filtrate 
  from 
  the 
  silica 
  is 
  treated 
  with 
  a 
  slight 
  excess 
  of 
  ammonia, 
  

   and 
  the 
  solution 
  boiled 
  for 
  a 
  short 
  time 
  to 
  expel 
  the 
  excess. 
  The 
  

   solution 
  is 
  then 
  filtered, 
  the 
  precipitate 
  dissolved 
  in 
  dilute 
  hydro- 
  

   chloric 
  acid, 
  and 
  reprecipitated 
  in 
  the 
  same 
  way; 
  filtered 
  out, 
  

   washed 
  and 
  then 
  ignited 
  and 
  weighed, 
  giving 
  the 
  amount 
  of 
  

   alumina 
  and 
  iron 
  (as 
  Fe^ 
  O 
  3) 
  present. 
  The 
  combined 
  filtrates 
  from 
  

   the 
  iron 
  and 
  alumina, 
  which 
  should 
  be 
  concentrated 
  to 
  about 
  200 
  cc, 
  

   are 
  heated 
  to 
  boiling 
  and 
  about 
  25cc 
  of 
  sat 
  sol. 
  of 
  ammonium 
  

   oxalate 
  added, 
  and 
  the 
  boiling 
  continued 
  for 
  two 
  or 
  three 
  minutes 
  

   longer, 
  when 
  the 
  heat 
  is 
  removed 
  and 
  sufficient 
  ammonia 
  added 
  to 
  

   render 
  the 
  solution 
  strongly 
  alkaline. 
  The 
  precipitate 
  is 
  allowed 
  to 
  

   settle, 
  and 
  the 
  supernatant 
  liquid 
  decanted 
  off 
  as 
  closely 
  as 
  possible 
  

   through 
  a 
  filter; 
  hydrochloric 
  acid 
  is 
  then 
  added 
  to 
  the 
  precipitate 
  

   to 
  dissolve 
  it, 
  and 
  then 
  sufficient 
  ammonia 
  to 
  reprecipitate 
  it. 
  It 
  is 
  

   then 
  washed 
  on 
  to 
  the 
  filter; 
  washed; 
  ignited 
  with 
  sulfuric 
  acid, 
  

   and 
  weighed 
  as 
  calcium 
  sulfate. 
  The 
  filtrate 
  receives 
  a 
  farther 
  

   addition 
  of 
  ammonia 
  and 
  of 
  hydrodisodic 
  phosphate, 
  is 
  well 
  stirred, 
  

   allowed 
  to 
  stand 
  for 
  some 
  hours 
  in 
  the 
  cold, 
  when 
  the 
  magnesium 
  

   precipitate 
  is 
  filtered 
  out, 
  washed 
  with 
  ammonia, 
  igTuted 
  and 
  

   weighed. 
  

  

  