Am.  Jour  Pharm. ) 
August,  1883.  j 
Progress  of  Soda  Industry. 
425 
matical  principles,  the  connection  which  exists  between  the  dimensions  of 
the  chambers,  the  composition  of  the  gases,  the  intensity  of  the  reaction 
and  the  consequent  temperature  in  the  chambers,  as  depending  on  the 
method  of  combining  single  chambers  into  sets.  He  thinks  he  has  been 
successful  in  finding  a  law  applicable  to  more  complicated  reactions,  which 
he  expresses  in  the  following  words :  "  The  rate  of  chemical  change  depends 
on,  and  is  proportional  to,  the  facility  with  which  groups  of  molecules 
favorable  to  the  particular  change  can  form  in  the  system  in  which  the 
change  occurs."  Hurter  does  not  give  the  deduction  itself,  but  merely  a 
differential  equation  based  thereon,  into  which  he  introduces  the  amount 
of  sulphurous  anhydride,  oxygen,  water  and  nitrogen  compounds,  in  order 
to  find  the  dynamic  equation  representing  the  rate  of  the  formation  of  sul- 
phuric acid  in  the  chambers.    He  obtains  the  following  results : 
1.  As  the  chamber  space  is  increased  in  arithmetic  progression,  the  amount 
of  sulphurous  anhydride  not  converted  into  sulphuric  anhydride  decreases 
in  geometric  progression. 
2.  The  chamber  space  for  a  given  fixed  loss  of  sulphur  is  proportional 
directly  to  the  loss  of  the  gas,  or,  what  is  the  same  thing,  to  the  amount  of 
sulphur  burnt. 
3.  The  chamber  space  is  inversely  proportional  to  the  nitrogen  com- 
pounds and  aqueous  vapor  present. 
Hurter's  conclusions  as  to  temperature  show  that  the  excess  of  tempera- 
ture of  the  chambers  over  the  surroundings  for  successive  chambers  decreases 
in  geometric  progression,  and  that  the  temperature  of  the  leading  chamber 
depends  on  the  number  of  chambers  which  are  connected  into  one  system. 
In  discussing  the  manufacture  of  sodium  sulphate.  Lunge  mentions  that 
the  substitution  of  machine  power  for  manual  labor  is  becoming  more  and 
more  of  an  accomplished  fact.  I  n  England  the  processes  of  Jones  and  Mac- 
tear  are  competing  with  each  other.  Since  the  construction  of  the  furnace 
devised  by  Jones  and  Walsh  has  been  altered,  this  furnace  is  said  to  work 
satisfactorily,  although  it  is  less  generally  emploj^ed  than  Mactear's  salt 
cake  furnace.  In  general  construction  this  furnace  is  very  similar  to  Mac- 
tear's carbonator,  there  being,  however,  no  central  opening,  but  a  central 
division  or  pot,  into  which  the  salt  and  acid  are  continually  fed.  This^ 
pot  serves  as  a  mixing  vessel,  from  which  the  thin,  pasty  mass  flows  over 
into  the  first  division  of  the  bed,  where  the  first  stage  of  the  process  is  com- 
pleted. It  then  passes  successively  through  the  other  division  until  it 
reaches  the  outer  circumference  of  the  furnace,  where  it  passes  into  the 
delivery  trough  which  runs  all  round  the  furnace,  and  is  luted  to  prevent 
escape  of  gas.  The  materials  are  mixed  by  means  of  an  agitator  placed 
between  the  two  flues,  through  which  the  acid  vapors  mixed  with  the 
products  of  combustion  pass  away  to  the  condensers.  The  heating  of  the 
furnace  may  be  carried  out  as  most  convenient,  care  being  taken  to  obtain 
thorough  combustion,  so  as  to  prevent  soot  being  passed  on  into  the  con- 
densers. The  great  advantage  of  this  continuous  system  of  decomposing 
salt  is  to  be  found  in  connection  with  the  condensation  of  the  hydrochloric 
acid.  The  salt-cake  as  it  is  withdrawn  is  almost  entirely  free  from  smell  or 
acid  vapor  ;  there  is  no  difficulty  in  making  sulphate  of  97  per  cent,  from 
common  white  salt.     The  advantages  may  be  summarised  as  follows: 
