66 
Estimation  of  Alcohol. 
j  Am.  Jour.  Pharm. 
\   February,  1909. 
THE  INFLUENCE  OF  GLYCERIN,  ACETANILID  AND 
CERTAIN  OTHER  AGENTS  IN  THE  ESTIMA- 
TION OF  ALCOHOL. 
By  L.  E.  Warren  and  H.  C.  Fuller, 
Drug  Division,  Bureau  of  Chemistry, — Part  of  Report  on  Medicinal  Plants 
and  Drugs  to  the  Association  of  Official  Agricultural 
Chemists,   1908,  by  L.  F.   Kebler,  Referee. 
Some  time  since  the  question  was  raised  whether  or  not  the 
presence  of  glycerin,  acetanilid  and  certain  other  substances  in 
pharmaceutical  preparations  would  interfere  with  the  accuracy  of 
the  estimation  of  alcohol.  It  was  held  by  some  that  sufficient  glyc- 
erin, acetanilid,  etc.  (or  of  their  decomposition  products),  would 
be  carried  over  in  the  alcoholic  vapors  during  the  distillation  to 
raise  the  specific  gravity  of  the  distillate  appreciably,  thus  giving 
results  reading  below  the  truth  for  alcohol. 
An  examination  of  the  literature  showed  that  apparently  no  one 
had  investigated  this  particular  phase  of  the  problem,  though  several 
workers  have  recorded  their  observations  on  the  behavior  of 
glycerin  in  boiling  aqueous  and  alcoholic  solutions,  and  others  have 
noted  that  appreciable  losses  occur  when  acetanilid  is  dried  at  tem- 
peratures above  40°,  or  when  its  chloroformic  solution  is  evaporated 
on  the  water-bath. 
Couttolenc  1  states  that  if  glycerin  be  heated  on  a  water-bath  to 
90 0  C.  for  five  hours  it  will  lose  any  water  that  it  may  contain,  and 
that  then  the  evaporation  of  glycerin  proceeds  at  the  rate  of  about 
0.00317  gramme  per  hour  per  square  centimetre  of  surface  exposed. 
This  proportion  is  increased  by  the  admixture  of  sand  and  rapidly 
diminished  by  the  lowering  of  the  temperature. 
Nessler  and  Barth  2  have  shown  that  by  evaporating  solutions  of 
glycerin  (aqueous  or  alcoholic)  of  different  strengths  on  a  water- 
bath,  a  noticeable  loss  occurs.  They  concluded  that  the  loss  of 
glycerin  depended- upon  two  conditions:  the  strength  of  the  solution 
and  the  volume  of  water  evaporated. 
1  Repert.  Pharm.,  10,  73  (1882);  Abst.  Pharm.  Jour.,  Tr.  [3],  12,  804 
(1882). 
2  Z.  anal.  Chem.,  21,  44  (1882),  and  23,  327,  329  (1884)  ;  Abst.  J.  Chem. 
Soc,  46,  1434  (1884). 
