80 
Whiting  and  Its  Manufacture. 
Am.  Jour.  Pharm. 
Feb.,  1*86. 
into  large,  square,  open  iron  tanks  in  front,  under  which  is  conducted, 
by  draught,  a  current  of  strongly  heated  air  from  kilns,  placed  in 
front,  so  regulated  in  temperature  as  never  to  exceed  300°  F. 
At  the  proper  time,  which  ranges  from  five  to  six  days  for  the  first, 
to  from  six  to  eight  months  for  the  last,  each  bin  is  closed,  the  excess  of 
water  drawn  oif  from  above,  and  pumped  to  a  large  tank  upon  the  roof 
of  the  building,  for  re-use  in  grinding  crude  chalk,  and  the  sluice-gates 
below  are  opened  to  allow  the  Avhite,  viscid  mass  to  flow  into  the  flat, 
open  tanks  in  front.  As  soon  after  heating  as  the  mass  becomes  suffi- 
ciently plastic,  it  is  cut  into  blocks  of  about  one  cubic  foot,  weighing 
20,  30  or  40  pounds.  The  instrument  used  to  do  this  division  is  tech- 
nically called  a  "Scorer,"  and  is  simply  a  long,  stout  pole,  at  the  end 
of  which  is  attached  an  L  shaped  piece  of  iron.  The  mass  is  then 
again  slowly  heated,  from  beneath,  to  still  further  expel  moisture. 
From  there  these  blocks  are  conveyed  on  tramways  and  taken  to 
the  drying-room  above,  where  they  are  exposed  on  large  trays  to  the 
continued  draughts  of  atmospheric  air,  to  promote  thorough  dryness; 
which  point  of  the  process  is  reached  in  one  or  more  weeks,  according 
to  the  condition  of  the  weather.  Then  these  blocks  are  powdered, 
bolted,  graded  and  packed  in  barrels  of  about  300  pounds  each,  for 
shipment,  as  kiln-dried  whiting. 
To  a  limited  extent,  in  comparison  with  the  previously  described 
process,  there  is  another  mode  of  manufacturing  practiced,  whose  only 
difference  consists  in  the  method  of  drying  employed,  which,  in  this 
instance,  is  done  by  simple  exposure  of  the  viscid,  elutriated  chalk  to 
the  air,  without  previously  heating  to  expel  contained  moisture  and 
then  proceeding  as  before  mentioned.  This  product  so  obtained,  is 
called  air-dried  whiting,  in  contradistinction  to  the  kiln-dried  body 
and  must  of  necessity  contain  a  certain  percentage  of  unexpelled 
moisture;  the  presence  of  which  rendering  it,  by  giving  what  is  called 
"body,"  more  fit  for  certain  uses  in  the  arts  than  the  kiln-dried 
substance. 
In  the  grades  of  whiting  mainly  supplied  to  markets,  samples  are 
presented  in  the  order  of  their  grade  of  fineness;  the  lowest  grade 
being  mentioned  first,  the  finer  second,  the  still  finer  third,  and  so  on. 
A  is  "Chalk"  in  crude  form.  A  No.  1,  is  "Commercial,"  the  lowest 
grade  made  from  chalk.  A  No.  2,  is  "  Gilded,"  the  next  higher  grade 
made  from  chalk.  A  ~No.  3,  is  "American  Paris  White,"  the  finest 
grade  of  all  made  from  chalk.    On  the  other  hand  we  have  B  as 
