Am.  Jour.  Pharm. 
June,  1S00. 
An  Examination  of  Acacia. 
269 
Guichard,  in  examining  the  rotatory  powers  of  the  various  aca- 
cias, found  that  they  formed  three  series  according  to  their  specific 
rotatory  powers,  as  follows  :  those  of  Galam  and  Australia,  -(-  16  ; 
those  of  Arabic  and  Aden,  +  32;  while  gum  Ghatti  had  a  rotatory 
power  of  -f-  64.  He  explained  the  difference  by  viewing  the  gums 
as  mixtures  of  several  dextro-rotatory  and  laevo- rotatory  sub- 
stances.   {Client,  and  Drug.,  93,  144.) 
Taking  this  as  a  suggestion,  the  writer  examined  several  sample?, 
and  according  to  the  results  obtained  it  would  seem  that  this  point 
were  worthy  of  further  investigation. 
Appended  will  be  found  a  table  showing  the  behavior  of  the 
several  solutions  towards  polarized  light. 
Sample. 
Treatment. 
No.  1  
Dextrogyrate. 
aD.  18 
After  treatment  with  HC1,  dextrogyrate. 
ar>-  34' 
"  KOH, 
aD.  2 
"2  .... 
Previous  to  treatment,  laevogyrate. 
»D.  18 
After  treatment  with  HC1,  optically  inactive. 
"3  
Previous  to  treatment,  laevogyrate. 
*D.  iS 
"3  •  
After  treatment  with  HC1,  optically  inactive. 
Powdered  .... 
Previous  to  treatment,  laevogyrate. 
aD.  8 
After  treatment  with  HC1,  dextrogyrate. 
aD.  38 
Two  samples  of  commercial  dextrin  were  also  examined  opti- 
cally. Sample  No.  1  was  very  white  and  contained  a  large  per. 
centage  of  insoluble  material,  which  proved  to  be  starch. 
On  treating  10  grammes  of  this  sample  with  sufficient  water  to 
make  100  c.c.  and  filtering,  the  filtrate  was  found  to  have  a  specific 
rotatory  power  of  -f-  102.  Sample  No.  2  was  decidedly  yellow 
and  dissolved  readily  in  water.  In  treating  it  in  the  same  manner 
as  the  foregoing  sample  it  was  found  to  have  a  specific  rotatory 
power  of  +138. 
To  sum  up  the  results  of  these  experiments,  it  would  seem  that 
qualitative  tests  alone  are  of  very  little  value  for  detecting  dextrin 
in  powdered  acacia.  If  dextrin  is  used  for  the  purpose  of  adulter- 
ating powdered  acacia,  which  I  think  is  highly  improbable,  the 
supposition  is  that  a  very  white  sample  would  be  used. 
