CARBONATE  OF  POTASH  IN  IODIDE  OF  POTASSIUM.  357 
fermentation,  in  which  the  production  of  heat  induces  a  state  of 
desiccation  which  fits  the  bones  for  calcination. 
In  these  operations  the  bone  undergoes  a  great  alteration  :  the 
long  boiling  in  water  dissolves  a  great  portion  of  the  gelatine, 
which  is  necessary  for  the  production  of  a  good  black ;  and  the 
fermentation  and  long  exposure  to  the  air  causes  the  almost  total 
destruction  of  the  anintal  matter,  so  that  a  bad  black  is  produced 
for  the  sake  of  only  5  or  6  per  cent,  of  fat. 
The  author  states  that  much  more  advantageous  results  may . 
be  obtained  by  the  employment  of  sulphuret  of  carbon.  He  pro- 
poses to  crush  the  bones  almost  to  powder ;  then  to  treat  them 
with  this  agent,  which  almost  instantly  dissolves  all  the  grease 
contained  in  them  ;  and  from  this  it  may  be  separated  by  dis- 
tillation, which  is  greatly  facilitated  by  the  low  temperature  at 
which  this  fluid  boils,  and  the  ease  with  which  it  may  be  con- 
densed. The  quantity  of  grease  thus  obtained  is  10  or  12  per 
cent.,  and  it  is  superior  to  that  procured  by  boiling. 
He  adds,  that  the  same  agent  may  be  applied  to  the  extrac- 
tion of  oils  from  oleaginous  seeds  and  of  the  grease  from  wool. 
In  the  latter  case,  the  grease  extracted  becomes  a  useful  product ; 
it  is  a  butyraceous  substance,  adapted  for  the  manufacture  of 
some  kind  of  soap. — Chem.  Gaz.,  April  1,  1856,  from  Comptes 
Bendus,  February  4,  1856. 
TEST  FOE  CARBONATE  AND  IODATE  OF  POTASH  IN  IODIDE 
OF  POTASSIUM. 
Ry  Mr.  William  Copney. 
That  substances  used  in  medicine  should  be  absolutely  pure, 
however  desirable,  is  not  always  practicable ;  that  they  should, 
however,  be  of  such  a  degree  of  purity  as  not  to  affect  their  uses, 
is  imperative. 
Iodide  of  potassium  is  one  of  those  preparations  which,  in  the 
present  Pharmacopoeia,  are  consigned  to  the  list  of  the  Materia 
Medica,  no  formula  being  given  in  the  part  appropriated  to 
"preparations  and  compounds,"  "  inasmuch  as"— it  is  stated  in 
the  preface — "  we  have  these  medicines  so  adapted  to  our  use, 
that  we  have  no  occasion  to  prepare  them  ourselves ;"  a  state- 
ment, it  may  be  observed,  somewhat  refreshing  after  the  whole- 
