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PURIFICATION  OF  GLYCERINE. 
of  cosmetics.  It  was  established  from  the  experience  of  these 
medical  men  that  glycerine  when  applied  to  the  skin  softens  it, 
and  promotes  cicatrisation  of  cracks  and  fissures. 
The  memoir  of  M.  Bruare-Perrin  relates  to  the  means  of 
purifying  glycerine.  It  is  known  that  as  usually  obtained  it  has 
a  disagreeable  odor,  and  that  it  has  been  proposed  to  purify  it 
by  passing  through  it  a  current  of  carbonic  acid  gas  to  precipi- 
tate the  lime  which  it  contains.  According  to  M.  Bruere-Perrin 
this  mode  of  operating  only  removes  the  excess  of  lime  present 
and  not  that  combined  with  fatty  acids. 
M.  Bruere-Perrin  adopts  the  following  method  for  effecting 
the  object  required  : — 1st.  He  determines  by  means  of  oxalic 
acid,  the  quantity  of  lime  existing  in  the  liquid  to  be  purified. 
2d.  The  proportion  of  lime  being  thus  determined,  he  adds  to 
the  liquid  a  quantity  of  sulphuric  acid  sufficient  to  convert  the 
lime  into  insoluble  sulphate  of  lime.  3d.  He  then  concentrates 
the  liquor  in  a  tinned  copper  pan,  stirring  it  briskly  during  the  con- 
centration by  means  of  an  agitator  kept  in  motion  by  machinery. 
During  the  concentration  there  is  a  disengagement  of  vapors, 
having  a  disagreeable  odor,  and  a  partial  decoloration  of  the 
liquid  takes  place  at  the  same  time.  4th.  When  the  liquid  has 
acquired  a  density  of  1.075,  it  is  allowed  to  cool,  and  then  passed 
through  a  filter,  to  separate  the  sulphate  of  lime  ;  the  excess  of 
acid  which  has  been  used  in  the  previous  part  of  the  process  is  now 
saturated  with  carbonate  of  potash,  and  the  liquid  again  evapo- 
rated with  constant  agitation  until  it  has  a  specific  gravity  1.19, 
when  it  will  deposit  a  certain  quantity  of  sulphate  of  potash  in  a 
gelatinous  mass ;  it  is  then  allowed  to  cool,  strained,  and  the 
deposit  washed  with  a  small  quantity  of  water  to  which  a  little 
spirit  has  been  added.  5th.  It  is  again  evaporated,  still  keeping 
it  agitated,  and  after  bringing  it  to  a  specific  gravity  of  1.24 
while  hot,  it  is  left  to  cool,  when  a  further  precipitation  of  sul- 
phate of  potash  takes  place,  from  which  it  is  filtered. 
The  product  resulting  from  these  operations  is  of  an  amber 
color,  free  from  any  marked  odor,  having  a  sweetish  taste,  and 
being  unctuous  to  the  touch.  In  this  state  it  is  treated  while 
cold  'with  animal  charcoal,  and  filtered.  It  is  now  free  from 
color  or  any  sensible  odor. 
Glycerine,  like  water,  mixes  with  aqueous  liquids,  with  alcohol, 
