AMbfcUi;  im*"'}  Manufacture  of  Carbonate  of  Soda,  etc.  555 
immediate  future,  and  entirely  supersede  that  of  Leblanc.  Since  the 
time  of  the  Paris  Exposition  this  new  process  has  grown  from  a  small 
germ  to  a  strong  tree. 
The  process  in  question,  and  which  is  called  by  Prof.  A.  W.  Hof- 
mann  the  ammonia  process,  is  not  new  from  either  a  chemical  or  sci- 
entific point  of  view.  It  belongs  to  the  same  class  of  methods  as 
those  in  which  oxide  of  lead,  bicarbonate  of  magnesia,  quick  lime, 
alumina,  silicate  of  alumina,  oxide  of  chromium  or  fluosilic  acid  are 
employed  to  decompose  chloride  of  sodium  and  convert  it  directly  into 
soda  or  its  carbonate.  None  of  these  attempts  met  with  a  success 
deserving  of  notice,  although  for  a  century  past  efforts  have  been  made 
to  render  them  practically  operative.  The  new  process  is  founded 
upon  a.  reaction  noticed  over  thirty  years  ago — that  of  bicarbonate  of 
ammonia  upon  a  strong  solution  of  common  salt.  The  greater  part 
of  the  sodium  is  precipitated  as  a  bicarbonate,  while  chloride  of  am- 
monium remains  in  solution,  from  which  the  ammonia  for  a  second 
operation  is  expelled  by  quick  lime.  The  carbonic  acid  necessary  to 
convert  the  ammonia  into  bicarbonate  of  ammonia,  and  thus  make  the 
process  a  continuous  one,  is  obtained  by  heating  the  bicarbonate  of 
soda  to  convert  it  into  the  simple  carbonate. 
The  sensation  which  the  ammonia  process  has  created  in  industrial 
circles  will  render  a  brief  history  of  its  development  not  uninteresting. 
So  far  as  I  know,  Harrison,  Dyer,  Grey  and  Hemming  were  the 
first  to  patent  the  ammonia  process  in  Great  Britain  in  1838.* 
"  Great  expectations  "  were  excited  by  it,  but  it  soon  sank  into  obli- 
vion. Thirty  or  forty  years  ago  the  manufacture  of  soda  was  by  no 
means  at  the  head  of  the  great  branches  of  industry;  at  that  time, 
too,  ammonia  was  not  to  be  had  cheaply  and  in  immense  quantities 
and  that  branch  of  machine  building  which  has  furnished  the  necessary 
apparatus  for  chemical  industries  did  not  exist.  Besides  this,  Anthon, 
of  Prague,  in  1840,  claimed  to  have  proved  that  in  the  ammonia  pro- 
cess a  very  considerable  portion  of  the  common  salt  remained  unde- 
composed. 
After  a  sleep  of  sixteen  years  the  ammonia  process  again  entered 
the  field.  On  the  26th  of  May,  1854,  Turck  took  out  a  patent  in 
France,  and  on  the  21st  of  June,  the  same  year,  Schlcesing,  chemist 
of  the  Imperial  tobacco  factory  at  Paris,  took  out  a  patent  for  France 
and  Great  Britain.  The  mechanical  portion  and  machinery  for  Schlce- 
*■*'  M-echanics'  Magazine,"  xxxi,  page  48. 
