674  Alcohol  in  Volumetric  Analysis,  { 
Number  of  c.c.  of^  *L  KOH  solution  required  to  neutralize 
10  c.c.  of  JL  H2SO4  in  50  c.c.  of  the  following  : 
Indicators. 
JO 
j'o 
-a! 
0 
S3 
(U  O 
5  0 
5  O 
D  O 
Si 
o£ 
oii 
u 
V 
*-<! 
<v 
u  <q 
■-<j 
<u 
<u 
l« 
ai 
Ph 
Ph 
Ph 
10 
tn 
0 
10 
<N 
■* 
ro 
VO 
'5 
"*4 
50-1 
50-2 
50-2 
50-2 
50 
49*9 
49-8 
49-96 
49-8 
49'8 
50 
49*8 
49-8 
49-8 
49-98 
50 
50-2 
50 
50 
50-1 
50-2 
50 
50 
Iodo-eosin  
49-40 
49-6 
49*9 
49*45 
49**7 
48-98 
48-70  • 
49*15 
50'8 
51 
51-6 
50*65 
5° '9 
50 
50*7 
50*45 
49*8 
49'8 
49-8 
49-8 
50 
49  *9 
49*9 
49*9 
49-40 
49-46 
49-41 
49' 15 
49*5 
49*15 
49*2 
48*75 
49'5i 
4975 
49-8 
49  "4 
47*65 
47*5 
45*45 
46*55 
Phenolphthalein  
5i"i 
51-2 
50-8 
£0-8 
51*5 
51-2 
5i*4 
5i*05 
5i 
50-6 
50-8 
50-6 
50-2 
50-6 
50*4 
50 
50*25 
49'3 
50-8 
50 
48 
47*65 
48 
47*75 
On  comparing  the  results  contained  in  the  last  two  tables  with 
those  obtained  by  using  commercial  alcohol,  we  can  plainly  see  that 
the  disturbing  agent  is  an  impurity.  The  data  obtained  with  pure 
alcohol  vary  so  little  from  those  obtained  with  pure  distilled  water, 
that  the  differences  must  be  attributed  to  experimental  errors.  In 
the  case  of  methyl  orange  and  tropseolin  OO  the  stronger  alcoholic 
solutions  do  interfere  with  the  delicacy  of  the  end-reaction  to  such 
an  extent  that  the  results  are  entirely  unreliable. 
Eliminating  the  results  obtained  by  the  indicators,  whose  end- 
reactions  are  unsatisfactory,  viz.:  iodo-eosin,  fluorescein,  methyl  or- 
ange and  tropaeolin  OO,  the  average  impurity  indicated  is  equal  to 
nearly  1-8  c.c.  of  fiftieth  normal  alkaline  solution  for  every  50  c.c.  of 
commercial  alcohol ;  while  the  impurity  found  in  the  residues,  the 
4  litres  of  commercial  alcohol,  amounted  to  about  2  c.c.  of  the 
alkaline  solution  for  the  same  quantity  of  commercial  alcohol. 
As  the  result  of  some  recent  investigations  that  Professor  J.  U. 
Lloyd  and  the  writer  are  carrying  on,  the  former  made  some  com- 
parative volumetric  determinations  in  aqueous  and  alcoholic  solu- 
tions, which,  by  permission,  are  given  below : 
