ON  TINKALZITE  FROM  PERU. 
61 
coincides  pretty  well  with  my  analysis  of  some  specimens  from 
Peru. 
Tinkalzite  is  found  in  the  layers  of  nitrate  of  soda  of  South- 
ern Peru,  in  the  shape  of  globular  masses,  which  the  natives 
call  tiza,  and  which  vary  in  size  from  that  of  a  nut  to  that  of  a 
potato.  The  outer  crust  of  these  tubercles  is  rather  hard ;  but 
they  are  easily  broken,  and  are  then  seen  to  be  formed,  in  the 
interior,  of  a  mass  of  crystalline  needles,  intersecting  each  other 
in  all  directions,  and  of  a  brilliant  white  satiny  appearance. 
Often  these  globular  masses  contain  reddish  crystals  of  gypsum 
and  other  minerals  ;  and  they  always  contain  a  certain  quantity 
of  common  salt,  which  gives  to  the  mineral  a  brackish  taste. 
Water  extracts  from  tinkalzite  all  its  chloride  of  sodium  and 
borax ;  acids  easily  dissolve  the  whole  mineral,  leaving  only  a 
small  residue  of  very  fine  sand. 
Tbe  density  of  tinkalzite  I  find  to  be  1.93  (according  to  M. 
Kletzinsky,— 1.9212  ;  and  according  to  M.  Ulex,  the  satin-like 
fibres  =  1.8). 
The  analysis  of  the  mineral  in  question  has  given  me  the 
following  result,  by  the  side  of  which  I  have  placed  the  analysis 
of  M.  Kletzinsky  : — 
American  Tinkalzite.  African  Tinkalzite. 
Phipson.  Kletzinsky. 
Water                            34  00    37.40 
Soda                               11.95    10.13 
Lime                             14.45    14.02 
Boracic  Acid                   34.71    36.91 
Chlorine                           1.84    1.33 
Sulphuric  Acid                  1.10    0.50 
Silica                              0.60    « 
Sand                               2.00    " 
Phosphoric  Acid               traces    " 
Alumina                             "    u 
Magnesia                           "    " 
100.00  100.00 
The  diiference  in  the  quantities  of  water,  as  shown  in  these 
two  analyses,  is  owing  to  the  gradual  loss  of  water  by  soda- 
salts  when  exposed  for  some  time  to  the  air. 
By  neglecting  the  accidental  elements,  and  calculating  the 
