138 
Determination  of  Alcohol. 
(Am.  Jour.  Pharm. 
\     March,  1909. 
Calculation :  Subtract  specific  gravity  No.  I  from  specific  gravity  No.  2 
and  subtract  difference  from  i.ooo.  Consult  tables  for  alcoholic  strength  of 
liquid  of  resulting  specific  gravity. 
3.  Repeat  Experiment  No.  2  with  following  modification  : 
Instead  of  diluting  to  50  c.c.  with  water,  transfer  residue  from  capsule 
to  cylinder  with  small  amount  of  water  and  when  at  same  temperature  dilute 
to  25  c.c.  with  water  at  same  temperature.  Then  add  from  a  25  c.c.  pipette, 
exactly  25  c.c,  exactly  95  per  cent,  alcohol  at  same  temperature.  Mix,  adjust 
to  exactly  50  c.c.  with  water  and  take  specific  gravity  at  same  temperature 
(Gr.  No.  2)  (Westphal). 
Calculation :  Algebraically  subtract  specific  gravity  No.  1  from  specific 
gravity  No.  2  and  subtract  the  algebraic  difference  from  the  specific  gravity 
of  47.50  per  cent,  alcohol  at  same  temperature  (0.9392  at  15.60  C).  Consult 
tables. 
4.  Compare  results  of  method  3  with  those  of  methods  1  and  2. 
The  results  obtained  with  the  taraxacum  solutions  are  now- 
appended.  They  do  not  at  all  reflect  the  degree  of  care  taken  in 
obtaining  them,  and  might  be  criticized  as  indicating  a  lack  of  care 
in  making  the  determinations.  At  the  risk,  nevertheless,  of  their 
being  thus  criticized,  they  are  given  because  they  serve  to  bring  out 
certain  points  of  value. 
Solution 
Theoretical 
percentage 
(approximate) 
Experiment 
No.  1 
(distillation) 
Experiment  No.  2 
"  wine  "  method 
(dilution  with 
water) 
Experiment  No.  3 
modified  method 
(Dilu.  to  dil. 
ale.  strength) 
A  
23-75  - 
21.23 
2I.IO 
24.IO 
24.IO 
21.40 
2I.8o 
Aver.  21.19 
-2.56 
Aver.  24.10 
+  0.35 
Aver.  2r.6o 
-2.15 
B  
47-5o  | 
I 
46.00 
46.20 
46.73 
48.42 
47-42 

Aver.  46.10 
— 1.40 
Aver.  46.73 
-0.77 
Aver.  47.92 
+  0.42 
C  
[ 
71.25  j 
I 
71.00 
70.86 
72.23 
72.30 
71.97 
71-38 
Aver.  70.93 
-0.32 
Aver.  72.27 
+ 1.02 
Aver.  71.67 
+  0.42 
In  the  above  table,  the  figures  marked  -f  or  —  indicate  the  per- 
centage above  or  below  theoretical,  of  the  average  of  duplicate 
determinations. 
Attention  is  called  to  the  fact  that  with  the  progressively  more 
dilute  solutions  B  and  A  in  the  case  of  Experiment  Xo.  I,  there  goes 
