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MANUFACTURE  OF  AMMONIA,  ETC 
describes  a  method  of  distilling  the  volatile  solution  of  ammonia 
for  the  purpose  of  producing  ammonia  of  a  more  highly  concen- 
trated character.  For  this  purpose  he  employs  a  tower,  circular 
by  preference,  which  should  be  about  ten  diameters  in  height ; 
this  is  to  be  furnished  with  gratings,  placed  from  three  to  four 
feet  apart  throughout  the  whole  height  of  the  tower ;  the  spaces 
between  each  being  filled  with  coke,  pieces  of  earthenware,  or 
other  substances,  to  form  greatly  divided  media.  The  volatile 
solution  to  be  distilled,  whether  pure  or  combined  with  other 
matters,  is  to  be  introduced  at  the  top  of  the  tower,  and  allowed 
to  percolate  through  the  coke,  while,  at  the  same  time,  a  jet  of 
steam  or  heated  air  is  introduced  at  the  bottom,  which,  in  its 
ascent,  meets  the  ammonia  distributed  over  a  great  amount  of 
surface,  by  which  means  the  more  volatile  parts  of  the  ammonia 
become  vaporized  and  carried  off  by  the  steam  ;  this  being  .col. 
lected  at  the  top  and  conveyed  to  a  refrigerator  and  condensed, 
while  the  waste  liquor  escapes  at  the  bottom  of  the  tower.  As 
an  auxiliary  to  this  apparatus,  another  tower  is  placed  on  the 
top  of  that  already  described.  This  the  patentee  calls  a  concen- 
trator :  it  is  filled  with  the  same  materials  as  the  other,  and  fur- 
nished with  a  coil  of  pipe,  through  which  the  solution  of  am- 
monia is  to  be  passed  when  introduced  to  the  lower  tower ;  the 
vapors  arising  from  this  partially  vaporize  the  ammonia  in  the 
pipe,  while,  at  the  same  time,  the  more  aqueous  parts  of  the  va- 
pors are  condensed  before  passing  off  to  the  condenser. 
Dr.  Richardson's  process,  patented  January  26,  1850,  for 
manufacturing  sulphate  of  ammonia,  consists  in  subliming  the 
double  salt  of  sulphate  of  magnesia  and  ammonia  obtained  by 
the  following  method  : — The  ammoniacal  liquor  of  the  gas-works 
is  added  to  a  solution  of  sulphate  of  magnesia,  with  application 
of  heat,  until  the  solution  is  rendered  nearly  neutral ;  the  pre- 
cipitate is  then  allowed  to  subside,  and  the  clear  liquor  drawn 
off,  concentrated  by  boiling  to  from  50  to  60°  Twaddle  (spec, 
grav.  1,250  to  1,300],  and  crystallized.  If  preferred,  the  gas- 
water  may  be  neutralized  by  sulphuric  acid  before  it  is  added  to 
the  solution  of  sulphate  of  magnesia.  The  double  salt  of  sul- 
phate of  magnesia  and 'ammonia  may  also  be  obtained,  by  sub- 
jecting the  sulphate  of  magnesia,  either  in  solution  or  in  a  damp 
state,  to  a  current  of  ammoniacal  gas,  obtained  by  the  distilla- 
