TANNIN  IN  BRITISH  GALLS. 
487 
fly.    They  were  found  to  contain  an  average  of  15*97  per  cent, 
of  tannin. 
II.  Galls  gathered  when  mature  (in  the  month  of  August),  not 
perforated.  These  were  found  to  contain  17*65  per  cent,  of 
tannin. 
III.  Galls  gathered  when  about  half  developed  and  dried,  pro- 
ducing a  more  dense  and  shrivelled  gall.  These  contained  13*4 
per  cent,  of  tannin.  It  appears  from  this  that  the  mature  galls, 
gathered  before  the  escape  of  the  fly,  contain,  as  might  have  been 
expected,  the  largest  quantity  of  tannin. 
With  these  data  we  may  turn  to  the  second  question,  "  Can 
they,  at  either  of  these  periods,  be  employed  economically  as  a 
substitute  for  the  nut-galls  of  commerce  ?" 
The  quantity  of  tannin  contained  in  Aleppo  galls,  as  stated  by 
various  authors,  ranges  from  30  to  65  per  cent.,  which  is  obvious- 
ly much  more  than  that  contained  in  these  British  galls ;  yet, 
with  so  considerable  a  percentage  of  tannin,  there  are  probably 
some  uses  to  which  they  may  be  advantageously  applied.  I  have 
not  yet  been  able  to  make  any  experiments  with  a  view  to  ascer- 
tain if  gallic  or  tannic  acids  may  be  commercially  prepared  from 
them.  I  will,  however,  if  deemed  desirable,  take  up  that  point 
and  report  thereon  at  the  next  meeting  of  the  Conference. 
One  purpose  for  which  these  galls  may  undoubtedly  be  used  is 
that  of  dyeing ;  and  as  large  quantities  of  Aleppo  galls  are  con- 
stantly in  demand  for  this  purpose,  British  galls  would  here  find  . 
one  of  their  most  important  applications.  Another  use.  would  be 
in  making  ink.  I  have  made  some  ink  from  a  formula  known  as 
Wollaston's,  using  the  same  weight  of  British  as  Aleppo  galls. 
The  product  is  a  fair  average  ink,  with  which  this  paper  is  writ- 
ten. I  used  the  old  perforated  galls ;  had  I  used  a  larger  quan- 
tity of  these,  or  used  some  of  the  mature  galls,  it  would  probably 
have  made  a  better  ink.  No  other  tannin-yielding  material  was 
added.  They  might  also  be  used  for  some  kinds  of  tanning 
Oak-bark,  according  to  Davy,  yields  from  5  to  7  per  cent,  of 
tannin,  with  which  these  galls  stand  in  favorable  comparison,  and 
they  might,  in  some  cases,  be  advantageously  substituted. 
The  quantity  of  these  galls  in  some  districts  is  very  considera- 
ble, and  their  collection  in  quantity  would  be  easy. 
