ON  THE  MANUFACTURE   OF   GLYCERIN.  355 
action.  It  and  its  salts  were  all  burnt  in  the  same  manner  as  the 
rhodeoretine  : — 
Carbon    -    -    -  52-44    52-61    52'48    52-89   72  52*94 
Hydrogen  -    -  -   7*93     8*04      7-87     7-82    64  7-84 
Oxygen  -    -    -    3963    39-35    39-65    39'29    40  39*22 
Rhodeoretinic  acid  is  insoluble  in  ether,  soluble  in  all  propor- 
tions in  alcohol  and  water.    The  aqueous  solutions  of  the  acid  or 
the  neutral  ammonia  salt  are  not  precipitated  by  any  neutral 
metallic  salt;  basic  acetate  of  lead  gives  a  very  voluminous,  floc- 
culent,  white  precipitate.     The  acid  expels  carbonic]  acid  from 
alkaline  and  earthy  carbonates,  as  well  as  from  carbonate  of  lead, 
especially  by  boiling.    It  behaves  towards  acetic,  nitric,  and  con- 
centrated sulphuric  acid  precisely  as  rhodeoretine  does. — London 
Chem.  Gaz.,  Jan.  15,  1853. 
ON  THE  MANUFACTURE  OF  GLYCERIN. 
0     By  Campbell  Morfit,  M.  D; 
Glycerin  is  generally  made,  on  the  large  scale,  either  by 
directly  saponifying  oil  with  oxide  of  lead;  or  from  "the  waste," 
or  spent  leys  of  the  soap  makers.  The  first  mode  of  obtaining 
it  is  complex  and  expensive,  while  in  the  latter,  the  difficulty  of 
wholly  separating  the  saline  matters  of  the  "waste,"  renders  it 
impossible  to  obtain  a  perfectly  pure  product.  In  view  of  these 
obstacles,  arid  the  increasing  demand  for  the  article,  both  in 
medicine  and  perfumery,  I  submit  a  new  process,  which  has  been 
found,  by  actual  practice,  to  combine  the  great  and  desirable 
advantages  of  economy  of  time,  labor  and  money. 
Take  one  hundred  pounds  of  oil;  tallow,  lard  or  "stearin," 
(pressed  lard,)  place  it  in  a  clean  iron  bound  barrel,  and  melt  it 
by  the  direct  application  of  a  current  of  steam.  While  still 
fluid  and  hot,  add  15  pounds  of  lime,  previously  slaked  and  made 
into  a  milk  with  2i  gallons  of  water,  then  cover  the  vessel  and 
continue  the  steaming  for  several  hours,  or  until  the  completion 
of  the  saponification.  This  is  known  when  a  sample  of  the 
resulting  and  cooled  soap  gives  a  smooth  and  lustrous  surface  on 
being  scraped  with  the  finger  nail,  and  breaks  with  a  cracking 
noise.    By  this  treatment,  the  fat  is  decomposed,  its  acids  unite 
