AoitJo0ber,Pis96T'}    Recent  Contributions  to  Pharmacy.  S71 
To  demonstrate  the  action  of  water  in  assisting  the  action  of 
chloroform,  the  authors  give  the  results  of  a  number  of  assays  of 
tea  which  contained  2-50  per  cent,  of  alkaloid,  as  follows: 
Per  Cent. 
Process  Employed.  obtained. 
Dry  tea  extracted  by  anhydrous  chloroform   .  .  -   o  18 
"  "         hydrated  "   0-32 
"  "         boiling  "   048 
Moist  tea  extracted  by  chloroform  (process  of  Petit  and  Legrip),  2*50 
Process  of  Grandval  and  Lajoux,  dry  tea  and  ammonia  2*44 
r  After  completely  drying  the  mixture   0*30 
Commaille's  ]  The  mixture  being  sijglltiy  moist  1*20 
process    .  [>£h.e  mixture  being  very  moist  2*50 
Tea  treated  with  boiling  water,  dried,  then  extracted  with  chloro- 
form  020 
Tea  treated  with  boiling  water,  dried,  then  moistened  and  ex- 
tracted with  chloroform  2*50 
Tea,  lime  and  water,  having  the  consistence  of  paste,  dried  and 
then  extracted  with  chloroform   o"8o 
Tea,  lime  and  water,  dried,  then  moistened  with  water  and  ex- 
tracted with  chloroform  2*47 
Tea  dried  and  extracted  with  alcohol  of     980  o*88 
"  8o°  2-38 
6o°  2-36 
Tea  and  magnesia  extracted  by  alcohol  of  980  076 
8o°   2-34 
6o°   2-38 
1  gramme  dried  caffeine  and  4  grammes  of  slaked  lime,  mixed  to 
a  paste  with  water,  dried  and  extracted  with  chloroform    .  .  .  99/7 
1  gramme  dried  caffeine  and  4  grammes  of  calcined  magnesia, 
mixed  to  a  paste  with  water,  dried  and  extracted  with  chloro- 
form  99 -8 
The  authors  conclude  from  their  experiments  that  magnesia  and 
lime  do  not  combine  with  caffeine  in  Commaille's  process,  that  their 
presence  in  the  assay  process  is  useless,  and  that  the  following 
method  of  Petit  and  Legrip  is  the  most  satisfactory:  25  grammes 
of  pulverized  tea  are  mixed  with  three  times  their  weight  of  boiling 
water,  and  allowed  to  remain  in  contact,  with  frequent  agitation,  for 
a  quarter  of  an  hour.  The  mixture  is  evaporated  on  a  water  bath 
until  it  is  just  moist,  it  is  then  placed  in  a  percolator  and  exhausted 
with  chloroform.  The  solvent  is  distilled,  the  residue  is  dissolved  in 
hot  water,  passed  through  moistened  filter  paper  and  evaporated  on 
a  water  bath  to  dryness.  The  product  is  usually  sufficiently  pure  to 
weigh.  The  process  is  equally  valuable  for  the  estimation  of  caf- 
feine in  coffee,  kola,  mate  and  guarana. 
