628 
Chemical  Notes  on  Tea. 
Am.  Jour.  Pharm. 
Dec,  1887. 
coffee1  was  capable  of  furnishing  satisfactory  results,  and  that  with  care- 
ful manipulation  the  amount  of  theine  in  tea  could  thus  be  determined 
with  considerable  accuracy. 
For  this  purpose  5  gms.  of  powdered  tea  is  moistened  with  hot 
water,  well  mixed  with  1  gram  of  hydrate  of  lime,  and  the  whole 
dried  on  a  water-bath.  The  dry  residue  is  then  transferred  to  a  small 
percolating  apparatus  and  extracted  with  strong  alcohol.  The  clear 
liquor  is  to  be  evaporated  to  remove  alcohol,  and  the  remaining  water 
solution,  measuring  about  50  cc,  mixed  with  a  few  drops  of  dilute 
sulphuric  acid,  which  separates  a  trace  of  lime  and  partially  decolo- 
rizes the  liquid.  After  filtering  the  slightly  acid  solution,  it  is 
transferred  to  a  separator  and  well  shaken  with  chloroform,  which 
gradually  abstracts  the  theine.  This  part  of  the  operation  requires 
particular  care,  for  though  theine  is  freely  soluble  in  chloroform  it  is 
necessary  to  shake  the  acidified  water  solution  with  several  successive 
quantities  of  chloroform  in  order  to  remove  the  whole  of  the  theine. 
Unless  the  quantity  of  theine  is  very  large,  about  200  cc.  of  chloro- 
form will  be  sufficient  for  5  gms.  of  tea,  and  that  should  be  used  in  five 
or  six  separate  portions,  testing  the  last  portions  by  distilling  off  the 
chloroform  in  a  weighed  flask  until  it  is  found  that  there  is  no  more 
theine  taken  up.  The  whole  of  the  chloroform  solution  is  then  to  be 
placed  in  a  stoppered  separator  and  shaken  with  a  very  dilute  solu- 
tion of  caustic  soda.  This  will  remove  a  small  quantity  of  coloring 
matter  and  render  the  theine  solution  quite  colorless,  so  that  on  distill- 
ing off  the  chloroform  from  a  weighed  flask  the  theine  remains  in  a 
condition  fit  for  weighing.  When  the  operation  is  carefully  carried 
out  the  theine  will  be  perfectly  white.  In  this  way  we  have  been 
able  to  obtain  results  of  great  uniformity. 
Our  first  experiments  were  made  with  Indian  and  Cingalese  tea, 
the  general  result  showing  that  both  kinds  contained  a  much  higher 
percentage  of  theine  than  has  hitherto  been  generally  supposed,  and 
that  the  variation  in  the  amount  of  this  substance  was  not  considera- 
ble. In  this  respect,  however,  there  seems  to  be  a  marked  difference 
between  tea  and  coffee ;  the  amount  of  theine  in  tea  is  by  no  means 
a  constant  quantity,  and  so  far  as  the  tea  of  India  and  Ceylon  is  con- 
cerned it  varies  from  3*22  to  4*66  per  cent.  This  is  taking  the  tea 
in  the  ordinary  air  dry  condition  in  which  it  is  met  with  in  commerce. 
The  following  table  gives  the  results  of  our  determinations  in  twenty- 
1  Pharm.  Joum.,  [3],  xvii,  921;  Amer.  Jour.  Phar.,  1887,  p.  94. 
