Am.  Jour.  Pharm. 
Dec,  1887. 
Chemical  Notes  on  Tea. 
627 
mine  the  amount  of  theine  in  tea  is  not  capable  of  furnishing  correct 
results,  since  the  greater  part  of  the  theine  is  decomposed,  and  this 
circumstance  will  account  for  the  low  results  obtained  by  him.  Peli- 
got's  method1  of  treating  an  aqueous  infusion  with  basic  lead  acetate, 
and  evaporating  the  filtrate  after  separating  excess  of  lead,  was 
equally  unsuitable  for  the  determination  of  theine,  since  its  extraction 
by  water  is  incomplete,  and  while  the  quantity  thus  obtained  cannot 
be  rendered  pure  by  crystallization  without  loss,  there  is  also  a  risk 
of  obtaining  too  high  a  result  if  the  product  is  not  sufficiently  puri- 
fied before  weighing.  Consequently  the  data  of  both  these  experi- 
menters cannot  be  relied  upon  for  accuracy,  and  the  results  of  some  pre- 
liminary experiments  furnished  us  with  evidence  that  a  further  in- 
vestigation of  the  subject  was  desirable.  Even  Zoller' s2  more  recent 
examination  of  a  sample  of  tea  from  the  Himalayas,  in  which  he 
found  4" 94  per  cent,  of  theine,  does  not  sufficiently  remove  uncer- 
tainty as  to  the  amount  of  theine  in  average  tea,  for  his  memoir  sug- 
gests that  the  tea  examined  by  him  was  of  exceptional  quality.  More- 
over, his  method  of  extracting  the  theine  by  thoroughly  disintegrating 
the  leaves  with  strong  sulphuric  acid  does  not  appear  well  adapted  for 
the  purpose.  Liebig  was  of  opinion  that  theobromine  was  also  ob- 
tained from  the  Himalaya  tea  examined  by  Zoller,  though  this  point 
was  not  settled  conclusively,  since  the  quantity  of  material  was 
too  small  for  the  purpose.  In  two  other  samples  Zoller  was  unable 
to  find  any  trace  of  theobromine.  In  our  analyses  of  tea  we  have  al- 
ways endeavored  to  trace  the  presence  of  theobromine,  but  so  far  we 
have  in  every  instance  obtained  only  negative  results.  It  must,  how- 
ever, be  mentioned  that  as  the  quantity  of  tea  operated  upon  for  the 
determination  of  theine  is  but  small,  a  minute  proportion  of  theobro- 
mine might  in  that  case  escape  detection,  and  we,  therefore,  propose  to 
operate  upon  large  quantities  to  decide  this  point. 
In  the  course  of  an  inquiry  undertaken  for  the  purpose  of  ascertain- 
ing the  circumstances  that  determine  the  differences  of  "strength"  in 
tea,  one  of  the  points  to  which  we  directed  our  attention  was  the 
extraction  of  the  theine  in  such  a  way  that  precise  analytical 
results  could  be  obtained,  admitting  of  a  comparison  of  different 
kinds  of  tea  in  regard  to  the  percentage  of  theine.  After  several 
trials  we  found  that  the  method  we  had  previously  adopted  for 
1  Ann.  Chim.  Phys.,  [3],  xi.,  138. 
2  Ann.  Chem.  Pharm.,  clviii,  180;  Amee.  Joue.  Phae.,  1871,  p.  353. 
