9° 
Detection  and  Determination  of  Alcohol  { Am  FJe0bu^arm 
previously  placed  3  cc.  of  the  soda  solution.  The  liquid  in  the  tube  is  then 
heated,  kept  at  the  boiling  point  for  a  few  seconds  and  placed  aside  for 
a  couple  of  hours.  If  *i  per  cent,  of  alcohol  was  contained  in  the 
original  solution  the  contents  of  the  test  tube  will  be  of  a  deep  yellow 
color,  and  will  have  deposited  flocks  of  aldehyd  resin  ;  with  '05  per 
cent,  no  resin  is  formed,  but  the  fluid  is  deep  yellow  and  perceptible 
opalescent ;  with  *oi  per  cent,  the  color  is  just  perceptible,  but  the 
characteristic  odor  is  still  very  distinct.  To  make  a  more  accurate 
determination  dilute  1  part  of  pure  aldehyd  with  200  of  water,  to  this 
add  30  parts  of  the  caustic  soda  solution  and  treat  in  the  same  way  as 
the  above  distillate.  After  the  lapse  of  two  hours  (the  reaction  not 
being  complete  for  nearly  this  length  of  time)  dilute  with  200  parts  of 
warm  methylated  spirit  and  add  water  to  500  parts.  This  solution  is 
quite  clear  and  of  a  reddish-yellow  color  and  will  keep  for  some  time,, 
especially  if  not  exposed  to  the  light.  Mix  5  cc.  of  this  solution  with 
45  cc.  of  water  in  a  glass  such  as  is  employed  for  nesslerizing, 
and  take  this  as  a  standard  solution.  It  does  not  keep  more  than 
two  or  three  hours,  hence  fresh  standards  must  be  from  time  to 
time  prepared,  or  a  solution  of  bichromate  of  potash  made  of  equal 
depth  of  color  (the  tint  being  almost  identical)  and  kept  as  a 
standard  of  reference.  To  make  the  quantitative  determination, 
dilute  the  distillate  with  sufficient  warm  spirit  to  make  a  clear  solu- 
tion and  add  water  to  50  cc.  Upon  ascertaining  the  quantity  of  thi 
solution,  which  must  be  diluted  with  water  to  50  cc.  to  bring  the 
depth  of  color  to  that  of  the  standard  solution,  the  percentage  of 
alcohol  in  the  original  solution  is  immediately  known.  The  following 
are  fair  specimens  of  the  results  obtained  : 
Strength  of  Alcoholic  Solution. 
02  per  cent 
1  " 
Strength  calculated  from  result 
of  experiments. 
OI2 
089 
I 
088 
092 
166 
208 
039 
170 
.308 
(3  cc.  K2Cr207Sol.) 
Having  ascertained  the  reliability  of  the  method,  where  the  alcohol 
