﻿Ammonium 
  Magnesium 
  Arseniate 
  of 
  Analysis. 
  61 
  

  

  In 
  no 
  one 
  of 
  the 
  many 
  precipitates 
  tested 
  by 
  silver 
  nitrate 
  

   for 
  included 
  chlorides 
  was 
  more 
  than 
  an 
  inappreciable 
  trace 
  

   found. 
  

  

  Evidently, 
  when 
  ammoniacal 
  magnesia 
  mixture, 
  amounting 
  

   to 
  about 
  thirty 
  cubic 
  centimeters 
  in 
  excess 
  of 
  the 
  theoretical 
  

   amount 
  necessary 
  to 
  precipitate 
  all 
  the 
  arsenic 
  as 
  the 
  ammo- 
  

   nium 
  magnesium 
  arseniate, 
  is 
  added 
  to 
  the 
  faintly 
  acid 
  solu- 
  

   tion 
  of 
  arsenic 
  acid 
  (carrying 
  no 
  ammonium 
  salts) 
  in 
  a 
  volume 
  

   not 
  exceeding 
  two 
  hundred 
  cubic 
  centimeters, 
  the 
  precipitate 
  

   appears 
  to 
  fall 
  in 
  ideal 
  condition. 
  If 
  the 
  precipitated 
  salt 
  is 
  

   transferred 
  to 
  the 
  filtering 
  crucible 
  by 
  the 
  aid 
  of 
  portions 
  of 
  

   the 
  filtrate 
  used 
  as 
  the 
  washing 
  liquid 
  and 
  finally 
  washed 
  on 
  

   the 
  asbestos 
  with 
  about 
  twenty 
  -five 
  cubic 
  centimeters 
  of 
  faintly 
  

   ammoniacal 
  water 
  — 
  an 
  amount 
  which 
  is 
  quite 
  sufficient 
  after 
  

   the 
  transfer 
  has 
  been 
  made 
  — 
  no 
  arsenic 
  gets 
  into 
  solution. 
  The 
  

   weight 
  of 
  the 
  carefully 
  dried 
  and 
  ignited 
  pyroarseniate 
  indi- 
  

   cates 
  with 
  accuracy 
  the 
  amount 
  of 
  arsenic 
  present. 
  

  

  I 
  wish 
  here 
  to 
  thank 
  Professor 
  F. 
  A. 
  Gooch 
  for 
  the 
  help 
  

   and 
  advice 
  he 
  has 
  constantly 
  given 
  throughout 
  this 
  work. 
  

  

  