68 
Estimation  of  Alcohol. 
f  Am.  Jour.  Pharm. 
\   February,  1909. 
and  increasing  loss  when  heated  above  40 °,  the  loss  being  much 
greater  at  higher  temperatures.  For  example,  between  48 0  and  55 0 
0.5000  gramme  heated  for  one  hour  lost  0.00066  gramme,  while  be- 
tween 85 0  and  900  the  loss  was  0.03625  gramme. 
In  estimating  acetanilid  Puckner  9  has  observed  that  there  is  no 
loss  when  a  chloroform  or  ether  solution  is  evaporated  at  room 
temperature  and  the  residue  evaporated  over  sulphuric  acid.  If  the 
evaporation  be  made  from  a  narrow  necked  flask  at  50°-6o°  the  loss 
is  but  slight,  while  at  95 0  the  loss  is  appreciable. 
In  the  case  of  the  United  States  against  Robert  N.  Harper,10  the 
chemist  for  the  defense,  John  G.  Hird,  testified  that  in  making  a 
determination  of  alcohol  by  the  A.O.A.C.  method  with  a  mixture  of 
water,  alcohol,  glycerin  and  acetanilid,  he  found  that  the  distillate 
"  was  not  pure  and  that  it  contained  glycerin  and  also  a  small  amount 
of  acetanilid  which  had  distilled  over  with  the  alcohol." 
In  order  to  determine  to  what  extent  (if  any),  glycerin,  acetanilid, 
and  some  other  substances  influence  the  determination  of  alcohol, 
a  number  of  experiments  were  carried  out  which  are  detailed  in  this 
paper.  In  these  experiments  all  dilutions  and  measurements  were 
made  at  200.  This  was  accomplished  by  rilling  graduated  flasks 
nearly  to  the  mark  and  placing  them  in  a  water-bath  kept  at  con- 
stant temperature.  At  the  end  of  from  thirty  to  sixty  minutes  the 
content  was  made  up  to  the  mark.  The  specific  gravity  determina- 
tions were  made  with  a  pycnometer  at  ^  for  alcohol  and 
for  glycerin.  All  alcoholic  strengths  are  given  in  percentage  by 
volume. 
Several  methods  of  procedure  were  employed.  In  one  a  known 
volume  of  diluted  alcohol  of  known  strength  was  diluted  with  a 
known  volume  of  diluted  glycerin,  the  resultant  mixture  assayed, 
and  the  result  compared  with  that  calculated  from  the  dilution.  In 
another,  a  given  volume  of  diluted  alcohol  of  known  strength  was 
distilled  to  the  same,  volume,  after  adding  about  10  per  cent,  of 
glycerin,  or  about  3  per  cent,  of  acetanilid,  or  1  per  cent,  of  antipyrin, 
and  the  result  compared  with  the  duplicate  to  which  no  addition  had 
been  made.  In  another  300  c.c.  of  diluted  alcohol  of  known  strength 
were  diluted  to  500  c.c,  after  the  addition  of  glycerin,  acetanilid, 
etc.    The  alcohol  was  then  determined  and  the  result  compared  with 
•  Pharm.  Rev.,  23,  302  (1905). 
10  Oil,  Paint  and  Drug  Reporter,  73,  10,  column  4  (1908). 
