224 
Manufacture  of  Cellulose. 
Am.  Jour.  Pharm. 
April,  1884. 
MANUFACTURE  OF  CELLULOSE. 
The  use  of  sulphurous  anhydride  in  the  manufacture  of  cellulose  is 
becoming  of  more  importance  every  day.  In  1876  Mitscherlich  recom- 
mended treating  finely  divided  wood  under  pressure  with  a  solution  of  cal- 
cium bisulphite  obtained  by  placing  calcium  carbonate  in  a  tower  and 
introducing  water  into  the  top  and  sulphurous  anhydride  into  the  bottom. 
Paper  made  from  the  resulting  cellulose  was  found  to  be  exceedingly 
tough,  and  has  been  sold  as  a  second  quality  parchment  paper,  although  it 
does  not  possess  the  qualities  which  characterize  this  paper.  The  details  of 
Mitscherlich's  process  have  since  been  kept  secret.  Francke  works  with 
solutions  of  calcium,  magnesium,  or  sodium  sulphite  of  4°  to  5°  15.,  at  a 
pressure  of  4  to  5  atmospheres,  the  operation  being  completed  in  12  to  15 
hours.  He  uses  rotary  horizontal  cylindrical  boilers  lined  with  lead,  the 
lining  being  independent  of  the  outer  casing,  thus  forming  a  separate 
boiler.  The  essential  theoretical  difference  between  the  lime  and  the  mag- 
nesia process  is  that  the  resulting  calcium  sulphate,  being  almost  insoluble, 
remains  in  the  lignose,  whilst  the  magnesium  sulphate  is  removed  during 
the  wa>hing  operation.  At  present  it  is  uncertain  whether  other  differ- 
ences exist  between  the  two  processes. 
The  cost  of  pulp  by  Eckmann's  method,  depending  on  the  use  of  magne- 
sium sulphite,  is  26  marks  per  100  kilos.,  the  selling  price  being  about  40 
marks.  During  last  summer  this  method  was  tested  by  a  number  of  French, 
paper  manufacturers  with  the  following  results:  The  quantity  of  wood 
employed  was  4,395  kilos.,  in  the  form  of  fir  planks.  The  loss  by  removal 
of  knots  in  chopping,  grinding,  etc.,  amounted  to  825  kilos.  The  remain- 
ing 3,570  kilos,  yielded  1,437  kilos,  dry  cellulose,  corresponding  with  32  68 
per  cent,  of  the  original  wood.  The  latter  contained  21  per  cent,  of  moist- 
ure, so  that  the  yield  on  the  dry  substance  is  equal  to  40  per  cent.  This 
is  considerably  less  than  the  yield  obtained  by  the  Francke-Mitscherlieh. 
process;  the  quality  of  the  pulp,  however,  is  far  superior.  According  to 
recent  trials  made  by  Eckmann,  it  is  shown  that  it  is  possible  to  obtain  at 
will  either  isolated  cells  or  fibrous  bundles  by  using  either  hydrogen  mag- 
nesium sulphite  or  magnesium  sulphite.  In  the  former  case,  the  coloring 
and  glutinous  substances  are  completely  dissolved,  whilst  in  the  latter  case 
a  portion  of  the  gluten  remains  in  the  fibres. 
Archbold  macerates  the  woody  tissue  with  dilute  milk  of  lime,  saturates 
with  sulphurous  anhydride  at  a  pressure  of  4  to  5  atmospheres,  and  washes 
the  mass  w7ith  water. 
Tilghman's  method  consists  in  boiling  in  closed  vessels  wood,  esparto  or 
flax,  with  sulphurous  anhydride  or  calcium  bisulphite,  or  both. 
Pictet  recommends  the  use  of  liquid  sulphurous  anhydride.  Finely 
divided  wood  is  first  immersed  in  water,  and  for  every  litre  120  grams  of 
liquid  sulphurous  anhydride  is  added.  At  a  temperature  of  85°  a  pressure 
of  7  atmospheres  is  produced,  so  that  the  incrustating  substances  of  the 
wood  are  strongly  attacked.  The  pulp  has  the  grey  color  of  the  original 
wood,  but  may  be  easily  bleached. 
In  discussing  the  sulphite  treatment,  Bourdilliat  contradicts  the  state- 
