﻿M. 
  Austin 
  — 
  Double 
  Ammonhim 
  Phosphates. 
  211 
  

  

  Garrigues' 
  method 
  of 
  procedure 
  was 
  to 
  add 
  acid 
  diammonium 
  

   phosphate 
  to 
  a 
  warm 
  solution 
  of 
  zinc 
  exactly 
  neutralized 
  with 
  

   either 
  hydrochloric 
  acid 
  or 
  ammonia 
  so 
  that 
  the 
  weights 
  of 
  zinc 
  

   ammonium 
  phosphate 
  and 
  that 
  of 
  the 
  diammonium 
  phosphate 
  

   added 
  should 
  be 
  as 
  one 
  to 
  five 
  respectively, 
  to 
  heat 
  until 
  the 
  

   flocky 
  precipitate 
  becomes 
  crystalline 
  and 
  subsides, 
  filtering 
  

   off 
  on 
  asbestos, 
  drying 
  at 
  100° 
  C. 
  and 
  weighing 
  preferably, 
  

   although 
  the 
  residue 
  may 
  be 
  ignited 
  without 
  loss, 
  since 
  the 
  fil- 
  

   tration 
  is 
  made 
  on 
  asbestos 
  in 
  a 
  perforated 
  crucible. 
  Langmuir"^ 
  

   modifies 
  the 
  method 
  by 
  destroying 
  with 
  dilute 
  acetic 
  acid 
  any 
  

   free 
  ammonia 
  that 
  may 
  be 
  left 
  in 
  the 
  solution 
  after 
  boiling. 
  

  

  In 
  the 
  work 
  that 
  follows, 
  in 
  which 
  an 
  attempt 
  was 
  made 
  to 
  

   show 
  what 
  precipitate 
  is 
  formed 
  from 
  a 
  solution 
  of 
  zinc 
  by 
  the 
  

   action 
  of 
  a 
  soluble 
  phosphate, 
  also 
  what 
  effect 
  ammonium 
  

   chloride 
  has 
  upon 
  the 
  precipitate, 
  a 
  solution 
  of 
  zinc 
  chloride 
  

   prepared 
  as 
  detailed 
  below 
  was 
  employed. 
  The 
  pure 
  zinc 
  

   chloride 
  of 
  commerce 
  was 
  treated 
  with 
  zinc 
  carbonate, 
  filtered 
  

   and 
  precipitated 
  with 
  ammonium 
  sulphide. 
  This 
  precipitate 
  

   was 
  boiled 
  in 
  a 
  slight 
  excess 
  of 
  hydrochloric 
  acid 
  until 
  all 
  the 
  

   hydrogen 
  sulphide 
  was 
  removed, 
  and 
  then 
  was 
  precipitated 
  

   with 
  sodium 
  carbonate. 
  After 
  washing 
  carefully 
  until 
  all 
  the 
  

   chloride 
  was 
  removed, 
  the 
  greater 
  part 
  of 
  the 
  carbonate 
  was 
  

   dissolved 
  in 
  sulphuric 
  acid 
  in 
  slight 
  excess, 
  boiled 
  with 
  the 
  

   remaining 
  portion 
  of 
  the 
  carbonate 
  and 
  filtered. 
  This 
  solu- 
  

   tion 
  diluted 
  to 
  definite 
  volume 
  was 
  standardized 
  as 
  sulphate 
  by 
  

   evaporating 
  the 
  solution 
  to 
  dryness 
  in 
  a 
  platinum 
  crucible 
  and 
  

   heating 
  the 
  residue.f 
  The 
  heating 
  is 
  carried 
  on 
  safely 
  by 
  so 
  

   placing 
  the 
  platinum 
  crucible 
  in 
  a 
  radiator 
  (consisting 
  of 
  a 
  cru- 
  

   cible 
  and 
  a 
  triangle) 
  that 
  the 
  bottom 
  of 
  the 
  platinum 
  crucible 
  

   was 
  held 
  about 
  one 
  centimeter 
  above 
  the 
  bottom 
  of 
  the 
  outside 
  

   crucible. 
  Constant 
  weights 
  were 
  obtained 
  in 
  successive 
  treat- 
  

   ment 
  with 
  a 
  few 
  drops 
  of 
  sulphuric 
  acid 
  and 
  heating 
  over 
  the 
  

   radiator. 
  The 
  results 
  obtained 
  in 
  this 
  manner 
  were 
  a 
  trifle 
  

   higher, 
  though 
  in 
  fair 
  agreement 
  (when 
  the 
  nature 
  of 
  the 
  car- 
  

   bonate 
  process 
  is 
  taken 
  into 
  consideration) 
  with 
  determinations 
  

   of 
  the 
  zinc 
  in 
  the 
  solutions 
  as 
  oxide 
  after 
  precipitating 
  with 
  

   sodium 
  carbonate 
  with 
  the 
  usual 
  precautions, 
  filtering 
  off 
  on 
  

   asbestos 
  under 
  pressure 
  in 
  a 
  perforated 
  platinum 
  crucible, 
  

   washing 
  with 
  distilled 
  water, 
  drying 
  and 
  igniting. 
  Results 
  are 
  

   given 
  in 
  Table 
  II 
  showing 
  the 
  amount 
  of 
  zinc 
  sulphate 
  found 
  

   in 
  five 
  different 
  portions 
  each 
  of 
  forty 
  cubic 
  centimeters 
  of 
  the 
  

   solution 
  of 
  zinc 
  sulphate, 
  and, 
  for 
  comparison, 
  the 
  results 
  of 
  

   determinations 
  as 
  zinc 
  oxide 
  by 
  the 
  carbonate 
  processes 
  are 
  

   included. 
  

  

  *Jour. 
  Am. 
  Chem. 
  Soc 
  , 
  xxi, 
  115. 
  

  

  f 
  Rose-Finkener 
  Analytische 
  Chemie, 
  6*^ 
  Auflage, 
  vol. 
  ii, 
  111. 
  

  

  