Am.  Jour.  Pharm. ) 
February,  1909.  J 
Estimation  of  Alcohol. 
67 
Hehner  2  demonstrates  that  the  conclusion  of  these  last  two  ob- 
servers is  erroneous  in  that,  while  glycerin  doubtless  is  volatilized 
somewhat  at  the  temperature  of  the  water-bath  when  in  a  state  of 
high  concentration,  it  is  not  appreciably  volatilized  in  aqueous  vapor 
during  the  evaporation  of  the  water.  Aqueous  solutions  containing 
less  than  50  per  cent,  glycerin  showed  no  loss  after  several  hours 
boiling,  the  volume  being  kept  up  by  frequent  additions  of  water. 
The  loss  in  73.8  per  cent,  solution  was  insignificant.  Hehner  did 
not  experiment  with  hydro-alcoholic  solutions  of  glycerin  but,  since 
the  vapor  tension  of  alcohol  is  greater  than  that  of  water,  it  is  justi- 
fiable to  assume  that  no  glycerin  would  escape  with  the  alcoholic 
vapors. 
Gantter  4  reaches  the  conclusion  that  glycerin  and  water  mixtures 
do  not  lose  glycerin  on  evaporation  until  all  of  the  water  has  been 
evaporated.  This  author  did  not  observe  any  loss  of  glycerin  when 
an  alcohol  or  glycerin  mixture  was  evaporated. 
Struve 5  distilled  a  mixture  of  glycerin  and  water  of  known 
strength  and  collected  the  distillate  in  fractions.  He  then  evapor- 
ated both  the  residue  in  the  distilling  flask  and  portions  of  the 
fractional  distillates.  From  the  results  of  one  distillation  he  found 
a  loss  of  about  0.379  Per  cent-  calculated  as  glycerin.  His  results 
are,  however,  questionable  since  he  gives  no  intelligible  data  con- 
cerning the  kind  of  flask  used,  or  its  dimensions,  particularly  the 
mean  distance  from  surface  of  the  boiling  liquid  to  the  delivery.  It 
is  possible  that  some  glycerin  may  have  been  carried  over  me- 
chanically and  not  in  the  state  of  vapor. 
Yvon  6  states  that  acetanilid  sublimes  at  900  in  the  form  of  white, 
light  crystals. 
Beringer  7  has  noted  that  acetanilid  is  somewhat  volatile  at  the 
temperature  of  the  water-bath. 
Moerck  8  has  demonstrated  that  dry  acetanilid  suffers  a  constant 
3  Analyst,  12,  45,  65-7  (1887);  Abst.  /.  Chem.  Soc,  52,  1143  (1887). 
*Z.  anal.  Chem.,  34,  423~4  (1895);  Abst.  /.  Chem.  Soc,  68,  II,  537 
(1895). 
6Z.  anal.  Chem.,  39,  95-9  (1900);  Abst.  Analyst.,  25,  214  (1900);  Abst. 
/.  Chem.  Soc.,  78,  II,  446  (1900). 
6 /.  pharm.  chim.  [5],  15,  20  (1887)  ;  Abst.  Pharm.  Rev.,  17,  804  (1899). 
7  Am.  J.  Pharm.,  69,  150  (1897). 
8  Pa.  Pharm.  Assn.  Proc,  21,  111  (1898)  ;  Am.  J.  Pharm.,  70,  335  (1898)  ; 
Abst.  Am.  Pharm.  Assn.  Proc,  47,  751  (1899). 
