796  Miscellaneous  Mineralogical  Notes.  {ASeCe 
Analyses  of  3  sericitic  schists  from  Southern  United  States : 
Per  Cent. 
No.  1.    SiO.    47.10 
Fe203  plus  ALO3    38.00 
CaO    0.10 
K,0    10.94 
Na20   3.41 
H20  .'   1.65 
Total    101.20 
Per  Cent. 
No.  2.    Si02    46.90 
FeX),  plus  ALO3    37.30 
CaO   .  7   0.10 
K20  .     11.43 
Na20   3.81 
H20   0.78 
Total   100.32 
Per  Cent. 
No.  3.    Si02   45.65 
Fe.,0;)  plus  ALO,   40.30 
CaO    1.45 
K20  ,   11.69 
Na20    3  61 
H20   none 
Total    102.70 
Serecitic  Schist  No.  3  was  powdered  and  rendered  anhydrous  by 
gentle  ignition  before  analysis.  This  schist  yielded  82.9  per  cent,  of 
its  total  K20  by  the  following  process : 
Twice  the  calculated  amount  of  sulphuric  acid  theoretically  re- 
quired to  combine  with  the  Fe203,  A1203,  CaO  and  Na20  was  added 
to  the  powdered  mineral  and  sufficient  water  was  added  to  reduce 
the  strength  of  the  acid  to  approx.  30  per  cent,  absolute  H2S04  by 
weight.  The  mixture  was  heated  with  stirring  for  about  8  hours 
on  a  boiling  water  bath,  then  permitted  to  stand  at  room  tempera- 
ture over  night.  This  procedure  rendered  44.9  per  cent,  of  the 
total  K20  soluble. 
A  second  exactly  similar  treatment  applied  to  the  insoluble 
residue  from  the  first  extraction  rendered  still  more  of  the  total  K20 
soluble.  The  total  amount  of  the  K20  thus  rendered  soluble  by  the 
two  extractions  was  82.9  per  cent,  of  that  originally  present. 
