72 
CRYOLITE  AND  ITS  PRODUCTS. 
within  two  years  past,  imported  into  Philadelphia  thirteen  car- 
goes, or  nine  thousand  tons,  which  have  been  sent  to  their  works 
for  manufacture.*  The  greater  portion  of  this  has  been  used  for 
their  patent  Saponifier.  They  are  now  devoting  their  attention 
to  the  preparation  of  caustic  soda,  carbonates,  and  other  salts  of 
soda,  sulphate  of  alumina,  &c. 
Soda  is  obtained  from  cryolite  by  simply  mixing  with  lime, 
and  subjecting  to  heat.  The  fluorine  combines  with  the  calcium, 
forming  fluoride  of  calcium ;  while  the  remaining  metals  absorb 
oxygen  from  the  air,  and  become  alumina  and  soda.  Carbonic 
acid  is  then  passed  through  the  solution,  forming,  with  the  sodi- 
um, a  carbonate  of  soda,  which  remains  suspended,  while  the 
alumina,  being  insoluble,  is  deposited  at  the  bottom  of  the  vessel. 
The  carbonate  of  soda  is  deprived  of  its  acid  by  means  of  lime  in 
the  usual  manner,  and  thus  rendered  caustic,  and  fitted  for  the 
use  of  the  soap-maker. 
One  hundred  pounds  of  cryolite  yield — 
44   lbs.  dry  caustic  soda, 
or    75      "    "   carb.  " 
or  203      "  crystal  carb.  " 
or  119|  «  bicarb.  " 
and  24  "  alumina. 
The  sulphate  of  alumina  contains  2*82  of  sulphuric  acid  to  1 
equivalent  of  alumina,  therefore  this  is  more  than  a  neutral  salt 
(3'  being  neutral),  which  is  very  desirable  for  manufacturers  of 
paper,  calico  printers,  &c.f  It  is  also  entirely  free  from  iron, 
another  very  important  characteristic. 
There  is  another  very  important  use  to  which  cryolite  can  be 
applied.  By  a  fusion  of  one  part  of  cryolite  with  from  two  to 
four  of  pure  silex,  a  beautiful  glass  is  formed,  susceptible  of 
mould  and  polish,  and  capable  of  being  manufactured  into  an 
endless  variety  of  useful  and  ornamental  articles,  and  probably 
many  utensils  for  chemical  and  pharmaceutical  use  will  be  made 
of  it.  A  company  has  been  operating  in  Philadelphia  for  some 
time  past,  on  an  experimental  scale,  entitled  the  "  Hot  Cast 
Porcelain  Company."    The  results  have  been  so  satisfactory 
*  They  will  import  this  year  (1867)  eight  thousand  tons, 
t  The  English  often  contains  as  high  as  3-27  of  acid. 
/ 
