62  PHARMACEUTICAL  APPLICATIONS  OF  GLYCERINE. 
his  "  Chemical  Technology,"  gives  1776 ;  Demarquay,  in  his 
recently-published  treatise  "  De  la  Glycerine,"  Gerhardt,  and 
others,  1779 ;  M.  Chevalier,  in  reporting  on  a  paper  by  M. 
Bruere  Perrin  in  the  "Journal  de  Chimie  Me'dicale,"  1782-83  ; 
while  Dr.  Abbotts  Smith  and  others  make  it  as  late  as  1789  ; 
but  the  fact  that  Scheele  published  his  discovery  in  the  «  Trans- 
actions of  the  Royal  Academy  of  Sweden  "  in  1783,  seems  to 
prove  the  latter  date  erroneous.  It  is  to  M.  Chevreul,  however, 
that  we  are  indebted  for  giving  to  this  substance  "  a  local  habi- 
tation and  a  name,"  which  he  accomplished  about  thirty  years 
after  its  discovery,  by  demonstrating  the  true  part  it  played  in 
the  constitution  of  fatty  bodies  (viz.,  that  of  a  base,  combined 
with  stearic,  margaric,  and  oleic  acids).    He  gave  it  the  name 
of  glycerine,  it  having  been  previously  known  as  tbe  "  sweet 
principle  of  oils."     In  1844  it  was  first  used  in  England  as  a 
therapeutic  agent,  but  attracted  little  attention  till  the  publica- 
tion of  the  admirable  papers  of  M.  Cap,  in  the  "  Journal  de 
Pharmacie  et  de  Chimie  "  for  February,  1854,  and  MM.  Cap 
and  Garot  in  the  same  Journal,  August,  1854.    These  gentle- 
men pointed  out  the  peculiar  advantages  offered  by  glycerine  as 
a  solvent,  and,  by  a  very  complete  course  of  experiments,  sug- 
gested for  it  almost  innumerable  pharmaceutical  applications. 
They  devised  means  of  obtaining  it  in  a  much  greater  state  of 
purity  from  the  waste  liquors  of  the  soap-boiler  than  it  had  hith- 
erto been  supplied,  but  it  was  found  impossible  to  rid  it  entirely 
of  the  impurities  (especially  volatile  fatty  acids)  derived  from 
the  substances  used  in  the  manufacture  of  the  soap.  The  purest 
glycerine  was  at  this  time  obtained  during  the  process  of  making 
lead  plaster.    A  very  important  discovery  was  made  by  Mr. 
Richard  Albert  Tilghman,  of  Philadelphia,  about  this  date,  viz., 
the  possibility  of  separating  glycerine  from  fats  by  the  aid  of 
heat  and  water  only.    A  patent  was  granted  to  this  gentleman 
January  9th,  1854.    In  his  specification  Mr.  Tilghman  says, 
"  I  subject  these  fatty  or  oily  bodies  to  the  action  of  water  at  a 
high  temperature  under  pressure,  so  as  to  cause  the  elements  of 
these  bodies  to  combine  with  water,  and  to  obtain,  at  the  same 
time,  free  fat  acids,  and  solution  of  glycerine."  The  temperature 
used  by  Mr.  Tilghman  was  that  of  melted  lead  (612°  F.).  Great 
improvements  in  the  details  of  this  process  were  shortly  after- 
