194 
CRYOLITE. 
hills  that  rise  at  a  short  distance  from  the  edge  of  the  waters  of 
the  river. 
Like  most  mineral  deposits  it  lies  at  an  angle  (of  about  40°), 
underrunning  the  granite  mountains,  the  other  face  descending 
with  the  waters  of  the  bay.  The  shores  of  the  Fiord  are  very 
bold,  so  that  no  soundings  can  be  had  scarcely  a  vessel's  length 
from  shore. 
Chemical  Composition. 
Cryolite,  as  I  before  stated,  is  a  fluoride  of  sodium  and  alumi- 
num ;  it  will  therefore  have  as  its  formula  (3Na  Fl  +  Al2  Fl3) 
sodium  3  equivalents,  2  eq.  of  alumina,  and  6  eq.  of  fluorine  : 
3Na  =  69 
2A1=  27-26 
6F1=  114 
210-26  equivalents. 
As  it  is  found,  it  is  in  the  form  of  crystalline  mass,  having  a 
sp.  gr.  2*95,  hardness  2-05,  or  a  little  more  than  alabaster. 
Large  portions  of  it  are  often  found  perfectly  colorless  and  pure, 
and  unmixed  with  foreign  matter,  while  other  portions  of  it  con- 
tain crystals  of  spathic  iron  ore  (spathic  iron  is  a  carbonate  of 
iron,  an  ore  of  iron  having  a  foliated  structure,  and  a  yellowish 
or  brownish  color),  galena  or  sulphide  of  lead,  copper  pyrites 
with  silver,  iron  pyrites,  etc. ;  all  of  which,  though,  are  easily 
removed  by  mechanical  means,  and  do  not  take  any  part  in  the 
chemical  decomposition  or  processes  to  which  cryolite  is  sub- 
jected in  the  arts. 
The  value — I  may  say  the  main  value  of  cryolite,  as  a  source 
of  soda  and  alumina,  is  dependent  upon  the  extraordinary  purity 
that  attends  its  proportions  when  uesdonthe  large  scale  in  these 
industrial  enterprises.  The  carbonate  and  hydrate  of  soda, 
when  obtained  by  the  ordinary  processes,  from  the  decomposition 
of  common  salt,  are  always  contaminated  with  more  or  less  of 
the  foreign  salts,  remaining  undecomposed  from  the  processes 
through  which  they  pass,  or  introduced  unavoidably  as  impuri- 
ties in  the  ingredients  consumed.  With  cryolite,  however,  it  is 
different ;  the  decomposition  is  so  simple,  the  manipulations  so 
