April  i,  1897.]  THE  TROPICAL  AGRICULTURIST.  681 
The  next  process,  viz.,  fermentation,  is  the  most 
important  one  from  our  present  point  of  view — 
the  chemical  aspect  of  the  subject.  Strictly  speak- 
ing, it  ought  to  be  confined  to  a primary  fermenta- 
tion process  (probably  due  to  an  oxidising  enzyme) ; 
for  if  fermentation  is  further  encouraged  (by  allow- 
ing the  rolled  leaf  to  lie  about  heaped  up  for  any 
length  of  time,  for  instance)  the  tea  manufactured 
from  such  leaf  will  be  spoilt.  In  my  opinion,  this 
species  of  secondary  fermentation  and  decomposition 
always  begins  to  set  in  after  the  primary  fermenta- 
tion, or  oxidation  pure  and  simple,  has  proceeded 
far  towards  completion,  and  it  is  to  forestall 
the  secondary  fermentation,  more  especially  as  vyell 
as  to  fix  the  primary  fermentation,  that  the  first 
stage  of  firing  is  mainly  intended. 
Mr.  Bamber,  who  wrote  on  the  chemistry  of  tea 
asserts  that  there  is  no  fermentation  at  all  during 
the  process  which  popularly  bears  that  name  in  the 
industry,  and  he  bases  his  theory  on  several  ex- 
periments in  which  he  failed  to  discover  any  micro- 
organisms ; but  recent  research  has  shown  that  enzy- 
mes usually  possess  an  oxidation  action  ; and  again, 
if  the  process  is  only  an  oxidation  one,  why  is  it  of 
such  extreme  importance  to  “ fix”  it  by  the  first 
stage  of  firing  at  the  exact  moment  when  the  cli- 
max is  reached  ? For  the  firing  would  not  fix  oxida- 
tion, by  any  means,  but  would  strongly  tend  towards 
hastening  and  increasing  it.  Therefore,  I think  that 
there  is  every  reason  to  conclude  that  tlxe  technical 
term  “ fermentation”  is  quite  correct. 
My  theory  is  that  the  process  commonly  known 
as  fermentation  in  the  tea  industry  is,  during  a 
greater  part  of  the  time,  at  any  rate,  mainly  an 
oxidation  one,  but  that  later  on  (it  takes  a little 
time  for  the  microorganisms  to  develop  and  get  to 
work),  a fermentation  due  to  an  organism  mani- 
fested by  the  peculiar  rancid  odour  produced  by 
overfermentation  of  a butyric  nature  begins  to  be 
set  up,  which  it  is  desirable  in  the  extreme  to  arrest 
at  the  very  outset,  since  its  action  is  deleterious  to 
the  quality  of  the  tea. 
Fermentation  may  be  described  as  the  splitting  up 
of  complex  organic  substances  into  simpler  bodies, 
by  meaus  of  either  (1)  living  organisms,  or  (2)  natural 
ferments  or  enzymes. 
Living  germs  (micro-organisms)  are  responsible  for 
such  fermentative  processes  as  are  carried  on  by  the 
yeast  plant,  or  in  sour  milk,  rancid  butter,  or  when 
nitrogenous  matter  acts  on  sugar  to  produce  gum. 
The  natural  ferments  or  enzymes  are  named  dias- 
tase (in  malt),  emulsin  (in  almonds),  inverting  (in 
yeast),  pepsin,  ptyalin,  and  trypsin  (the  active 
principles  respectively  of  gastric,  salivary,  and  pan- 
creatic juices). 
The  primary  fermentation  that  I have  described  as 
being  the  only  one  to  be  encouraged  in  tea,  is  due  to 
one  of  the  second  class  {i.e.,  a non-living  ferment), 
whereas  the  secondary  fermentation,  which  is  the 
one  to  be  discouraged,  and  arrested  by  firing,  can  with 
a good  deal  of  certainty  be  ascribed  to  a living  germ 
or  organised  ferment. 
For  the  oxidation  process  to  be  accomplished  pro- 
perly the  following  points  should  be  observed  : — 
(1)  The  leaf  should  be  sufficiently  withered  and 
rolled,  and  then  should  be  sieved  to  sort  out  the  fine 
leaf  from  the  coarse,  as  it  is  impossible  to  obtain 
an  even  fermentation  if  the  two  kinds  are  not  dealt 
with  separately. 
(2)  A clean,  smooth  cement  floor  on  which  the  leaf 
should  be  evenly  spread,  not  too  thickly,  and  the 
leaf  should  be  kept  moist. 
13)  A dark,  cool,  airy  room,  with  a moist  deanght 
of  air  if  possible. 
(4)  The  temperature  of  the  leaf  should  be  kept  below 
85  deg.  F.  if  possible. 
As  regards  the  temperature  at  which  tea  should  be 
kept  during  the  oxidation  stage,  I have  given  what 
I consider  is  a minium  temperature  obtainable  un- 
der ordinary  circumstances  in  a tea-house  in  the  plains; 
but  I hold  that  a maximum  of  coolness  during  the 
operation,  so  as  to  protract  it  as  long  as  possible 
(without,  of  course,  reaching  the  point  when  the 
secondary  fermentation  is  in  active  force),  ought  to 
be  the  aim  in  view,  for  reasons  that  will  have  been 
noted  when  reading  the  remarks  on  the  formation  and 
decomposition  of  various  substances  during  the  pro- 
cesses of  manufacture.  In  fact,  it  would  be  well  worth 
while  to  ferment  teas  under  such  reduced  tempera- 
ture as  can  only  be  obtained  in  a tea  factory  by 
the  artificial  aid  of  a refrigerator.  I made  this  sug- 
gestion in  my  MS.  of  “ Tea  ” over  a year  ago,  but 
I was  misguided  enough  to  circulate  it.  Since  com- 
mencing to  write  this  paper  I was  apprised  of  the 
fact  that  a machine  had  been  brought  out  some- 
what on  these  lines;  but  as  it  did  not  altogether- 
carry  out  my  ideas  I determined,  without  delay, 
on  bringing  out  a machine  myself  embodying  all  the 
points  that  I found  from  a very  extensive  practical 
experierree  of  and  a large  number  of  experiments 
with  the  fermentation  of  tea,  were  requisite. 
One  of  the  most  importent  chemical  changes  at 
this  stage  is  an  increased  formation  of  essential 
oil,  which  it  has  been  an  aim  in  my  machine  to  en- 
ourage. 
The  astringency  of  the  tea  is  reduced  by  a 
further  conversion  of  part  of  the  tannin,  to 
which  this  quality  is  mainly  due,  by  a combination 
of  part  of  the  tanuo-acids  with  some  of  the  albut 
miuoid  matter,  into  a leathery  substance  which  im- 
parts the  characteristic  tough  feeling  to  the  leaf  at 
this  stage.  These  two  last  reactions  usually  com- 
mence miring  the  rolling  process. 
A small  quantity  of  the  tannin  is  changed  into 
gallic  acid  and  glucose,  and  it  would  be  a great 
advantage  if  more  of  it  underwent  this  change, 
since  gallic  acid  is  not  nearly  so  injurious  to  the 
human  economy,  when  taken  with  albuminoid  food, 
as  tannin. 
The  pleasant  aroma  and  nutty  flavour  of 
the  leaf,  so  markedly  developed  during  this 
process,  are  due  to  the  formation  of  severa- 
volatile  oils.  It  the  process  be  too  long  con- 
tinued, however,  acids  very  similar  to  those  presenl 
in  rancid  butter  are  formed,  viz.,  butyric  acid,  &c. 
Prolonged  firing  will,  of  course,  rid  the  tea  of  this 
disagreeable  feature,  but  only  at  the  expense  of  the 
greater  part  of  the  essential  oil  as  well.  This  aci- 
dity, due  to  butyric  fermentation,  causes  the  coagu- 
lation of  some  of  the  albuminoid  matter,  which  is 
chiefly  present  in  the  form  of  vegetable  casein  (legu- 
min),  which  is  an  alkaline  albumen  resembling  the 
casein  of  milk.  This  coagulation  is  unfortunate,  as 
it  converts  a valuable  food  material  (which  tea  is 
very  largely  provided  with)  into  an  insoluble  form, 
with  the  result  that  a large  supply  of  nutriment  is 
rendered  useless.  However,  were  it  not  already 
coagulated  by  the  tannin,  it  would  soon  become  so 
by  the  heat  to  which  it  would  be  subjected  in  the 
firing. 
Daring  the  first  stage  of  firing  an  increased  amount 
of  essential  oil  is  freed  by  the  bursting  of  the  cells 
and  a further  quantity  is  also  formed  by  cheraicaf 
action. 
Another  action  of  this  operation  is  to  arrest  the 
secondary  fermentation — by  which  I mean  that  fer- 
mentation which,  as  I have  already  explained,  begins 
to  set  in  wheu  the  oxidsition  has  about  reached  its 
critical  point.  It  also  removes  about  40  to  50  per 
cent  of  the  moisture  from  the  half-m&iiufactiued  tea. 
Special  attention  should  be  paid  to  avoid  most  of 
the  important  volatile  constituents  being  carried  away 
and  lost  owing  to  the  employment  of  too  high  tem- 
peratures and  draughts  of  too  great  a force. 
The  concluding  operation  that  tea  undergoes  in 
the  factories  where  it  is  manufactured  is,  of  course 
packing;  and  with  regard  to  this,  I may  mention 
that  It  not  infrequently  happens  that  wheu  a wooaen 
chest  is  opened,  on  its  arrival  in  the  docki  the  tea 
is  found  to  possess  a very  nasty,  cheesy  smell 
which  takes  some  time  to  completely  pass  off.  For 
some  time  the  only  explanation  for  this  rather  dis- 
agreeable feature  that  was  forthcoming  was  that  the 
tea,  under  certain  extraordinary  circumstances,  acted 
on  the  lead  lining  enveloping  it.  But  although  ex- 
periments were  tried  to  produce  this  state  of  things 
artificially,  no  such  action  could  be  got  to  occur- 
and  then  a new  theory  was  started,  placing  the  whole 
