^jSSmJm.*""*}  On  the  Detection  of  Exhausted  Ginger.  343 
ash  "  the  difference  between  the  weight  of  the  total  ash  and  the  ash 
insoluble  in  water.  The  aqueous  solution  can,  of  course,  be  used  for 
determining  the  alkalinity,  or  the  actual  potash  present. 
Dyer  and  Gilbard  found  the  proportion  of  soluble  ash  from 
genuine  ginger  to  vary  from  19  to  3  per  cent-,  with  an  average  of 
27,  while  Mr.  W.  C.  Young  found  in  seven  authenticated  samples  of 
ginger  a  range  of  1-8  to  2-6  for  the  soluble  ash.  Figures  for  five 
samples  of  genuine  ginger  of  unknown  origin  have  been  communi- 
cated to  us  by  Mr.  T.  H.  Pearmain,  and  show  soluble  ash  ranging 
from  i*8  to  2-7  per  cent.,  calculated  on  the  moisture-free  samples. 
The  following  are  Mr.  Pearmain's  figures  : 
1. 
2 . 
3- 
4- 
5- 
3-1 
3'9 
37 
5-0 
4'5 
22 
27 
2-4 
i-8 
2'0 
3'2 
3'o 
2 '5 
5'o 
4-2 
Alcoholic  extract  after  treatment  with 
27 
3"i 
3'4 
2-9 
3'o 
These  results  bear  out  in  the  main  those  of  Dyer  and  Gilbard. 
Contrary  to  the  general  impression,  for  the  manufacture  of  essence 
of  ginger  an  aqueous  or  very  dilute  alcoholic  liquid  is  employed. 
The  use  of  any  but  very  dilute  spirit,  75 0  U.  P.,  causes  the  solution 
of  a  considerable  quantity  of  resinous  matter,  which  is  precipitated 
when  the  essence  is  subsequently  diluted  with  the  water  of  the  gin- 
ger-beer. Hence,  the  use  of  alcohol  in  anything  more  than  the 
most  moderate  proportion  is  neither  necessary  nor  desirable,  and 
the  more  so  as  the  greater  part  of  the  pungent  and  flavoring  princi- 
ple of  ginger  is  readily  extracted  by  cold  water.  Exhausted  ginger 
having  already  been  subjected  to  treatment  with  water  or  a  slightly 
alcoholic  solvent,  the  soluble  portions  have  been  to  a  great  extent 
removed,  and  hence  such  ginger  yields  a  lower  extract  than  a 
genuine  article.  The  aqueous  extract  contains  a  considerable 
quantity  of  soluble  salts  of  organic  acids,  and  the  ash  is  corre- 
spondingly deficient  in  soluble  salts,  and  especially  in  compounds  of 
potassium.  In  consequence  of  the  presence  in  ginger  of  calcium 
salts  soluble  in  dilute  alcohol,  the  ash  left  on  igniting  the  proof- 
spirit  extract  often  considerably  exceeds  the  proportion  of  soluble 
ash.  This  curious  fact  is  no  doubt  due  to  the  conversion  of  these 
calcium  compounds  into  carbonate  by  ignition,  thus  rendering  them 
insoluble  in  water. 
