308 
CORK  AND  ITS  USES. 
eight  or  ten  years  after  the  first,  is  still  of  an  inferior  quality. 
The  third  crop,  collected  in  about  eight  years  after  the  second, 
is  usually  the  first  marketable  cork — that  is,  the  first  crop  that 
is  fit  for  cutting  into  bottle-corks.  When  the  trees  have  attained 
to  this  age,  so  that  three  crops  have  been  taken  off,  they  usually 
yield  a  supply  of  good  cork  about  every  seven  or  eight  years  ; 
and  its  quality  improves,  as  well  as  the  quantity  enlarging,  at 
each  successive  gathering.  The  season  chosen  for  the  cork 
harvest  is  usually  the  month  of  July  or  August. 
It  will  be  seen  by  the  foregoing  that  the  quality,  and  conse- 
quently the  commercial  value  of  cork  is  materially  affected  by 
soil,  length  of  time  allowed  in  growing,  and  also  of  care  in  col- 
lecting. There  is  as  much  difference  existing  in  the  quality  of 
cork  as  in  most  other  articles  of  daily  use.  The  finest  kind 
should  be  compact  and  firm,  but  at  the  same  time  not  hard,  of 
an  even  texture  or  grain,  and  of  a  slightly  pinkish  tint.  This 
kind  of  cork  is  generally  selected  by  wine  merchants  for  bottle- 
corks  ;  while  the  coarser  kind,  which  is  always  more  porous,  full 
of  small  holes,  and  perhaps  punctured  by  insects,  serves  for  bungs 
for  casks  and  for  the  various  other  applications  to  which  cork  is 
put  in  a  cheap  form.  When  cork  is  required  to  be  thick,  it  is 
usually  found  coarse,  as  it  must  be  allowed  a  longer  period  of 
growth  to  promote  its  thickness.  The  charring  or  singeing  pro- 
cess to  which  this  kind  of  bark  is  frequently  subjected,  for  the 
purpose  of  filling  up  the  pores  and  making  it  impervious  to  fluids, 
has  also  a  detrimental  effect,  as  it  secretes  an  empyreumatic  oil, 
which  is  given  off  and  frequently  taken  up  by  the  liquids  it  con- 
fines ;  but  there  is  no  doubt  that  care  is  taken  in  the  selection  of 
these  corks,  and  methods  adopted  for  the  prevention  of  this 
chemical  contamination,  as  much  as  possible.  This  operation  of 
charring,  to  which  all  cork  was  formerly  subjected  for  the  pur- 
poses we  have  just  mentioned,  has  been  partially  succeeded  of 
late  by  that  of  boiling  the  cork  and  and  afterwards  scraping  the 
surface.  This  is  said  to  improve  rather  than  to  deteriorate  the 
cork,  in  being  more  effectual  in  filling  up  the  pores. 
The  uses  of  cork  are  so  numerous,  and  its  applications  so  con- 
tinually increasing,  that  the  supply  of  late,  as  we  have  said 
before,  has  not  been  sufficient  to  meet  the  demand.    It  is  not 
