Am.  Jour.  Pharm. ) 
Oct.,  1878.  J 
Soluble  Essence  of  Ginger. 
495 
I  then  began  to  investigate  for  myself,  and  ultimately  succeeded  in 
making  an  essence  which  answered  my  requirements  ;  but  before 
giving  the  form  for  its  preparation,  allow  me  to  say  a  few  words  about 
the  varieties  of  ginger  and  of  the  essence,  or  rather  B.  P.  strong  tinc- 
tures, found  in  the  market.  On  making  the  soluble  essence  from  the 
B.P.  strong  tincture  obtained  from  different  houses,  I  was  much  struck 
by  the  varying  qualities  (judged  by  the  odor)  of  the  essences  made 
therefrom.  Most  of  the  strong  tinctures  were  of  a  deep  red-brown 
color,  and  contained  a  large  percentage  of  resinous  matter  in  solution, 
and  invariably  the  darker  the  tincture  the  more  inferior  the  essence. 
These  I  have  no  doubt  were  made  with  Jamaica  ginger  of  inferior 
quality,  for  I  find  that  the  cheaper  kinds  are  much  richer  in  resins, 
whilst  they  are  equally  poor  with  regard  to  the  volatile  aromatic 
principle.  In  the  strong  tincture  the  spirit  conceals  the  aroma  ;  hence 
it  is  difficult  to  compare  the  two  specimens  by  their  odor  without 
diluting  them.  Let  them  be  diluted,  however,  and  then  compare  the 
essence  prepared  from  fine  Jamaica  ginger  and  that  made  from  an 
inferior  variety.  The  difference  is  so  surprising  that  I  have  heard  an 
experienced  chemist  doubt  whether  the  fragrant  odor  of  the  former 
was  solely  due  to  the  ginger  used. 
To  return  to  my  subject.  After  finding  a  method  of  making  the 
soluble  tincture,  and  trying  the  effects  of  varying  the  proportions  of 
the  ingredients,  the  following  form  was  fixed  upon  as  yielding  upon  the 
whole  the  best  results  : 
Take  of  finest  Jamaica  ginger  in  powder  1  pound  ;  pour  upon  this 
8  ounces  of  rectified  spirit,  and  after  allowing  to  stand  for  several  hours 
add  more  spirit ;  percolate  to  16  ounces.  To  this  add  2  ounces  of 
heavy  carbonate  of  magnesia,  agitate  and  add  24  ounces  of  water. 
Shake  well  and  filter.  If  the  filtrate  is  turbid  the  whole  must  be 
shaken  with  a  little  more  magnesia  and  again  filtered.  The  filtrate 
possesses  all  the  aroma  of  the  ginger,  and  a  fair  share  of  its  pungency, 
and  is  of  a  pleasing  yellow-brown  color.  After  keeping  a  few  days  it 
becomes  turbid  and  deposits  slightly,  but  if  again  filtered  appears  to 
continue  clear. 
The  action  of  the  magnesia  probably  is  partly  mechanical,  partly 
chemical,  for  the  peculiar  tint  of  the  essence  is  undoubtedly  due  to  the 
action  of  the  hydrate  of  magnesia  upon  the  ginger  resin,  and  the 
precipitate  which  forms  soon  after  the  essence  is  first  made  is  a  com- 
