426 
Progress  of  Soda  Industry. 
(  A.m.  Jour.  Pharm. 
I    August,  1883. 
Beduced  cost  of  labor  and  fuel,  and  economy  of  sulphuric  acid.  Complete 
condensation  without  wash-towers,  no  weak  acid  being  produced.  Hydro- 
chloric acid  formed  of  greater  strength  than  by  an  open  furnace,  and  equal 
to  the  best  form  of  closed  furnace.  Complete  removal  of  nuisance  caused 
by  escapes  of  acid  vapors  during  the  working  or  discharging.  Small 
amount  of  wear  and  tear,  and  low  cost  for  repairs.  Better  quality  of  salt- 
cake,  rendering  it  specially  suitable  for  glass-making  purposes.  Ability  to 
use  rock  salt  alone.  Less  outlay  for  plant  to  decompose  a  given  amount  of 
salt  and  condense  all  the  acid  Referring  to  the  decomposition  of  salt  in 
hand-furnaces.  Deacon's  furnace  has  been  introduced  into  most  works  using 
muffle  furnaces. 
According  to  Weldon,  the  preparation  of  anhydrous  sodium  sulphate 
from  crystallized  Glauber  salt  by  Pechiney's  process,  is  effected  on  a  large 
scale  in  the  following  manner :  At  the  salt  works  of  Giraud,  the  mothel*- 
liquor  left  after  the  salt  has  crystallized  from  the  salt  water  when  subjected 
to  cooling,  deposits  large  quantities  of  sodium  sulphate,  associated  with  10 
atoms  of  water.    Pechiney  adds  to  Glauber  salt  a  certain  proportion  of 
sels  mixtes,"  i.  e.,a  mixture  of  sodium  chloride  and  magnesium  sulphate, 
which  is  deposited  during  the  concentration  of  the  mother-liquor  to  35°  B. 
by  sun  heat.  The  mixture  is  then  introduced  into  iron  cylinders,  and 
heated  to  70—80.  When  a  temperature  of  35°  has  been  attained,  the  con- 
tents of  the  cylinders  are  found  to  have  become  a  mixture  of  anhydrous 
sodium  sulphate  with  a  saturated  solution  of  "  selmixte,"  the  latter  having 
dissolved  in  what  was  the  water  of  liydration  of  the  sodium  sulphate.  The 
whole  is  then  machined  at  a  temperature  not  under  35°  (hence  Pechiney's 
object  in  heating  to  70—80),  when  the  full  quantity  of  anhydrous  sulphate 
corresponding  to  the  hydrated  sulphate  treated  is  obtained.  The  whole 
process  is  performed  in  a  very  short  time,  and  its  only  cost  is  for  a  small 
amount  of  labor  and  steam.  The  solution  filtered  from  it  is  employed  for 
the  production  of  more  hydrated  sulphate. 
Parnell  has  made  a  series  of  trials  on  the  action  of  potassium  nitrate  in 
the  manufacture  of  caustic  soda,  the  results  of  which  confirm  the  conclu- 
sion previously  arrived  at,  namely,  that  the  ammonia  evolved  from  the 
boiling  liquors  in  the  Leblanc  process  is  due  to  cyanide,  and  does  not  arise 
from  the  decomposition  of  the  nitrate. 
Referring  to  the  improvements  in  the  manufacture  of  chlorine,  Lunge 
mentions  Strype's  process  of  j^urifying  hydrochloric  acid  from  sulphuric 
acid  by  means  of  calcium  chloride.  This  method,  which  is  worked  success- 
fully at  Wicklow,  consists  in  adding  to  the  hydrochloric  acid  in  the  cold 
about  20  per  cent,  of  its  volume  of  the  solution  of  calcium  chloride,  obtained 
as  a  bye-product  in  the  Weldon  process.  Thus  almost  the  whole  of  the 
sulphuric  acid  originally  present  in  the  hydrochloric  acid  is  precipitated, 
and  may  be  separated  by  filtration. 
In  the  manufacture  of  potassium  chlorate,  as  at  present  ordinarily  con- 
ducted, there  is  a  loss  of  from  15-25  per  cent,  of  the  total  chlorate  produced. 
According  to  Pechiney's  improved  method,  this  loss  is  reduced  to  below 
5  per  cent.  The  improvement  in  question  was  devised  for  the  purpose  of 
reducing  the  cost  of  preparing  sodium  chlorate,  now  extensively  used  in  the 
printing  of  aniline-black.    Pechiney,  in  investigating  the  solubility  of  a 
