630 
Chemical  Notes  on  Tea. 
Am.  Jour.  Pharm. 
Dec,  1887. 
prices  mentioned,  that  the  marketable  value  of  tea  is  not  to  any 
great  extent  dependent  on  or  proportionate  to  the  amount  of  theine  it 
may  contain,  however  important  that  constituent  may  be  in  other  re- 
spects. Neither  can  the  "  strength  "  of  tea,  as  that  term  is  generally 
understood,  be  taken  as  proportionate  to  the  amount  of  theine.  This 
is  evident  from  the  results  of  the  analysis  of  the  two  samples,  26  and 
27,  which  were  selected  by  experienced  judges  of  tea  to  represent  ex- 
treme cases  of  difference  as  to  strength.  The  amount  of  theine  in  27 
is  greater  than  in  26,  but  to  such  a  small  extent  that  the  difference  in 
strength  of  the  tea  represented  by  those  samples  could  not  be  ascribed 
to  the  theine  they  contain. 
It  appears  to  be  much  more  probable  that  the  "  strength  "  of  tea  is 
chiefly  determined  by  the  amount  or  condition  of  the  astringent  con- 
stituent, the  precise  nature  of  which  is  at  present  only  partially  known. 
Moreover,  when  the  mode  of  preparing  tea  is  considered  it  is  also 
probable  that  this  quality  of  "  strength  "  may  be  largely  influenced  in 
degree  by  the  manipulation  of  the  leaves  in  the  process  of  manufac- 
ture, which  comprises  stages  of  fermentation  and  heating  in  the  moist 
state  in  contact  with  atmospheric  oxygen,  both  of  which  are  condi- 
tions likely  to  induce  alteration  of  material  analogous  to  ordinary 
tannin.  But  before  any  definite  opinion  on  this  point  can  be  offered 
in  place  of  the  general  probability  suggested,  it  will  be  necessary  to- 
acquire  a  better  knowledge  of  the  chemical  nature  of  that  constituent 
of  tea  leaves  which  in  some  respects  resembles  ordinary  tannin. 
The  commercial  value  of  tea  is  at  present  estimated  by  a  combined 
consideration  of  several  factors,  among  which  appearance  counts  to  a 
considerable  degree.  In  this  respect  the  size  of  the  leaves,  indicating 
their  age,  and  likewise  the  presence  of  what  is  termed  "tip,"  consist- 
ing of  the  unexpanded  leaf  buds,  serve  as  indications  by  which  tea  is 
classed  partly  as  Souchong  or  Pekoe,  and  partly  also  as  varieties  of 
those  kinds  of  tea.  In  addition  there  is  also  the  process  of  tasting 
procured  by  tea  brokers.  This  consists  in  preparing  infusions  of  the 
different  samples,  much  in  the  same  manner  that  tea  is  commonly 
used,  and  then  forming  a  judgment  as  to  the  value  of  the  samples  ac- 
cording to  the  aroma,  flavor  and  other  characteristics  of  the  corres- 
ponding infusions.  This  is  an  art  that  is  practised  with  a  surprising 
degree  of  precision,  so  that  the  results  arrived  at  by  different  opera- 
tors agree  in  a  very  remarkable  manner.  In  carrying  out  the  broker's 
test,  tea  is  infused  for  five  minutes  in  boiling  water  in  the  proportion 
