ON  I'ERRX  SUBCARBONAS. 
195 
powder.  The  portion  dried  at  the  lowest  temperature  being  the 
most  soluble. 
Tinctures  were  made  of  each  solution  by  the  addition  of  285 
grs.  of  alcohol,  as  before,  and  the  same  mode  of  procedure  re- 
sorted to  for  obtaining  the  insoluble  residues,  resulting  as 
follows  : 
Residue  of  specimen  dried  at  60°  F.    1-85  grs. 
«        «         160Q  to  175°  F.    6-25  grs. 
«  "        "    water  bath,  8-9  grs. 
Experiment  2d.  A  dilute  solution  of  sulphate  of  iron,  using 
2  oz.  to  1  pint  of  water,  was  mixed  with  a  solution  of  carbonate 
of  soda  of  the  same  proportion,  both  solutions  being  cold. 
The  same  precautions  with  regard  to  washing  the  precipitate 
were  observed,  successive  portions  of  warm  water  being  used, 
until  no  soluble  saline  matters  could  be  detected  in  the  wash- 
ings. 
The  protocarbonate  was  subjected  to  the  three  different  de- 
grees of  temperature,  60p  P.,  sand  bath  1G0°  to  175°  F.,  and 
water  bath,  and  when  dried  and  reduced  to  powder  was,  as  in 
the  former  experiments,  treated,  45  grs.  of  each,  with  132  grs. 
of  muriatic  acid.  In  comparing  the  respective  solubilities  of  these 
portions,  it  was  found,  as  before,  that  a  high  temperature  ren- 
dered the  subcarbonate  more  insoluble. 
When  alcohol  was  added  to  each  solution  in  the  proportion 
before  used,  and  the  insoluble  residue  obtained  as  in  the  previ- 
ous instances,  the  weight  in  grains  was  found  to  be — 
Residue  of  specimen  dried  at  60°  F.         1  gr. 
160°  to  175°  F.    6-65  grs. 
*<  *«  «         water  bath,        8-5  grs. 
Experiment  4th.  Diluted  solutions  of  sulphate  of  iron  and  car- 
bonate of  soda,  in  the  proportion  of  2  oz.  to  1  pint  were  mixed 
hot,  at  the  temperature  of  about  200°  F.,  and  the  resulting 
precipitate  washed  and  dried  at  the  three  different  temperatures 
before  named. 
When  treated  with  the  same  proportion  of  acid  used  in  the 
former  experiments,  this  mode  of  preparation,  which  accords 
with  the  direction  of  the  U.  S.  Pharmacopoeia,  was  found  to 
furnish  a  very  soluble  precipitate  ;  yet  as  in  the  other  instances 
a  high  temperature  used  in  drying  it,  rendered  the  subcarbon- 
ate less  soluble. 
