548  Detection  of  the  Adulteration  of  Tea. 
character.  The  use  of  a  standard  solution  of  gelatin  for  the  deter- 
mination of  the  strength  of  tannin  matters  was  nothing  new;  but  he 
believed  he  had  been  the  first  to  employ  the  process  in  the  examina- 
tion of  tea.  Mr.  Allen  then  described  the  details  of  the  method  he 
employed  in  the  estimation  of  tannin,  stating  that  he  had  found  by 
the  process  in  genuine  black  tea  of  rather  more  than  average  quality 
12*5  per  cent,  of  tannin,  which  presented  a  close  agreement  with 
those  in  the  old  analyses  of  Mulder,  which  he  regarded  as  the  most 
accurate  and  complete  analyses  of  tea  extant.  The  estimation  of  tan- 
nin was  of  the  first  importance  ;  for  if  it  reached  the  normal  amount 
all  question  of  adulteration  by  exhausted  leaves  was  at  an  end,  and 
foreign  leaves  were  very  unlikely  to  be  present.  The  only  fallacy  in 
such  a  conclusion  would  be  caused  by  an  admixture  of  catechu,  or  sloe 
leaves.  The  next  point  of  importance  was  the  percentage  of  "  woody 
fibre,"  as  it  was  called  by  some  analysts,  and  here,  again,  he  was  dis- 
posed to  think  that  Mulder's  analysis  was  the  only  accurate  one.  The 
percentage  of  gum,  insoluble  matter,  and  tannin  in  any  sample  of  tea, 
considered  carefully,  would  enable  the  analyst  to  form  a  very  accurate 
opinion  as  to  the  presence  or  absence  of  exhausted  leaves,  &c.  An- 
alyzed by  the  above  described  methods  a  sample  of  very  superior 
black  Congou  tea  gave  the  following  results,  which  he  had  placed  in 
juxtaposition  with  the  numbers  obtained  after  some  of  the  same  sam- 
ple had  been  infused  in  the  usual  manner  in  the  teapot  (the  exhaustion 
was  not  carried  to  excess,  no  second  quantity  of  tea  being  used),  and 
the  leaves  re-dried: — 
Original  Tea.      Exhausted  Tea. 
Moisture        .       .       .         92       .  Ill 
Insoluble  matter      .        .       58*7       .  87*5 
Gum  .       .       .       10-5       .  3-8 
Tannin  (by  gelatin)  .  15-2  .  3-3 
From  this  it  would  be  seen  that  infusion  in  the  teapot  resulted  in  the 
increase  of  the  insoluble  matter  by  nearly  30  per  cent.,  while  the  gum 
and  tannin  were  much  reduced  in  amount.  Generally  the  exhausted 
leaves  were  re-dried  and' made  up  with  gum,  which  gave  them  a  peculiar 
glossy  appearance,  and  was  detected  by  excess  on  analysis.  From  a 
table  which  he  had  prepared  of  thirteen  different  analyses,  he  gave 
several  instances  of  adulteration.  In  one  case  he  was  attracted  by  a 
table  in  a  window,  "  Try  our  fine  rough,  flavored,  thick,  sappy,  Mon- 
ing  Congou  at  2s  a  lb."    The  specimen,  when  examined,  was  found 
