IODINE  FROM  THE  ASHES  OF  SEA- WEEDS. 
535 
The  separation  of  the  soluble  contents  of  the  Kelp. 
The  kelp  is  to  be  broken  up  by  hammers  into  pieces  of  the 
size  of  egg  coal ;  these  are  introduced  into  the  steeps,  which  are 
square  cast  iron  tanks  about  six  feet  long,  four  wide  and  four 
deep,  with  a  faucet  in  the  side  at  the  bottom,  to  run  off  the  ley ; 
a  rude  filter  of  straw  and  cinders  is  placed  over  the  aperture  on 
the  inside  to  prevent  the  fine  dust  from  coming  through  with  the 
ley.  The  steeps  having  been  filled  with  the  broken  kelp,  (fold 
water  is  run  on  a  few  of  them,  the  number  depending  on  the  size 
of  the  establishment,  the  rest  are  not  watered  ;  after  standing 
eight  or  ten  hours  the  water  is  strongly  enough  charged,  the 
faucets  are  opened  and  the  clear  ley  run  into  a  cistern  below ; 
from  this  cistern  it  is  pumped  into  the  large  cast  iron  evaporat- 
ing vessels.  Of  its  concentration  there  we  will  have  occasion  to 
speak  hereafter.  In  the  mean  time  the  vessels  which  have  been 
emptied  are  again  filled,  but  this  time  hot  water  is  used  to  ex- 
pedite the  solution  ;  this  after  standing  a  night  is  to  be  run  off 
and  pumped  into  those  steeps  which  had  been  left  unwatered,  there 
1  to  take  up  from  the  fresh  kelp  a  sufficiency  of  salts  to  make  the 
ley  strong  enough  to  be  pumped  into  the  evaporating  pans,  thus 
saving  fuel.  In  this  way  in  a  well  regulated  work  the  liquor  of 
the  steeps  No.  1  are  run  on  to  No.  2,  and  these  as  they  become 
spent  are  run  on  to  No.  3,  thus  keeping  up  the  supply  of  strong 
ley  for  the  boilers  ;  this  is  a  most  important  point  in  the  economy 
of  an  iodine  work.  No.  1  being  exhausted,  is  again  to  be  filled 
and  covered  with  weak  lev  from  the  others,  and  so  on  in  rota- 
tion. 
Of  the  Boiling. 
And  first  of  the  Hydrometers.  The  Hydrometers  used  are 
those  known  as  Twaddle's,  and  are  three  in  number.  No.  1  is 
graduated  on  the  scale  of  water,  as  0°  at  the  top  in  degrees,  and 
numbered  at  every  second  degree,  as  2,  4,  6,  8  and  so  on  to  24°. 
The  use  of  No.  1  is  to  show  the  strength  of  the  ley  in  the  steeps 
when  getting  weak,  and  when  the  glass  sinks  to  2°  the  steep 
may  be  emptied.  These  are  useful  and  simple  instruments,  and 
very  easily  understood  by  the  workman.  The  ley  from  the 
steeps  should,  if  possible,  never  be  put  into  the  boilers  at  less 
than  30°  or  40°,  if  attainable,  as  this  will  obviate  the  necessity 
