78 
Whiting  and  Its  Manufacture. 
Am.  Jour.  Pharm. 
Feb.,  1886. 
The  main  source  of  supply  of  commercial  chalk,  is  from  the  cliff- 
hills  along  the  shores  of  the  North  Sea  and  the  banks  of  the  English 
Channel,  where  it  is  found  in  deposits  of  vast  extent,  consisting  of 
foraminiferous  microscopic  shells,  through  which  are  occasionally 
distributed  more  or  less  rounded  nodules  of  flint,  together  with,  very 
rarely,  a  specimen  of  petrified  fish.  Chemically,  it  is  almost  wholly 
calcium  carbonate  (Ca  C03),  with  small  and  varying  traces  of  ferric 
oxide  (Fe203),  alumina  (A1203),  magnesia  (MgO)  and  silica  (Si02). 
The  so-called  "  French  Chalk "  or  Talcum,  P.G.,  does  not  contain  any 
calcium  carbonate,  but  is  a  hydrated  magnesium  silicate  (4MgSi03* 
Si02-4H20). 
Next,  and  of  far  less  importance  than  the  common,  white  variety, 
we  have  "  Black  Chalk/'  a  soft  carbon-like  schist  that  may  be  used 
in  writing  or  drawing;  "Brown  Chalk,"  an  umber-like  body,  and 
"Eed  Chalk"  or  "Kiddle,"  an  impure  earthy  variety  of  haematite. 
The  red  varieties,  in  general,  may  contain  as  much  as  9*28  per  cent, 
silica,  9*6  per  cent,  ferric  oxide,  and  1*43  per  cent,  alumina1  and  the 
Norfolk  red  chalks,  in  particular,  leave,  on  treatment  with  acids  and 
subsequent  drying,  9*3  per  cent.,  argillaceous  residue,  consisting  of 
water,  ferric  oxide  and  alumina,  with  a  small  proportion  of  magnesium 
and  potassium.2 
Chalk  is  brought  from  Hull  or  London,  England,  on  board  ships 
as  ballast,  in  the  form  of  yellowish-white  or  white  (with  occasional 
streaks  of  red  from  traces  of  ferric  oxide),  insoluble,  soft  and  friable 
earth-like  masses,  irregular  in  shape  and  size,  variable  in  weight  and 
having  a  rough,  irregular  fracture,  and  insipid  taste ;  specific  gravity 
varying  about  from  2*4  to  2*6;  absorbent  of  moisture;  containing 
5,  10,  20,  or  more,  per  cent,  of  water.  Cliffstone  is  the  name  given  to 
a  variety  of  chalk,  from  which  it  differs,  mainly,  in  being  much  more 
hard  and  stone-like. 
For  the  year  ending  June  30,  1884,  the  amount  of  unmanufactured 
chalk  admitted  into  the  U.  S.  ports,3  duty  free,  amounted  to  33,677 
tons,  having  a  value  of  $26,856,  while  unmanufactured  cliffstone,  a 
variety  of  chalk  previously  referred  to,  amounted  to  6,003  tons,  hav- 
ing a  value  of  $11,701.  Independently  of  this,  for  the  same  year, 
5,000  to  6,000  tons  were  withdrawn  from  private  storehouses,  where 
1  Chem.  News,  1862,  Vol.  6,  p  313.  Chapman. 
2  Chem.  News,  1875,  Vol.  36,  p.  199.  Church. 
3  Commerce  and  Navigation  (U.  S.)  Reports,  1884,  p.  182. 
