Am'octuyi£6arm'}      Guarana.    Methods  for  its  Assay.  485 
magnesia.  80  cc.  of  nitrate  (corresponding  to  4  cubic  centimeters  of 
the  fluid  extract)  are  then  evaporated  to  dryness,  dried  one  half  hour 
at  100°  C,  cooled  and  weighed.  The  weight  in  grammes,  multiplied  by 
25,  gives  the  percentage  of  the  alkaloid  extracted  from  the  drug, 
and  this  percentage,  divided  by  the  specific  gravity  of  the  fluid 
extract,  gives  the  percentage  in  the  latter.  The  above  gives  results 
agreeing  with  those  obtained  in  the  same  fluid  extract  by  using 
Greene's  methods  slightly  modified.  Applying  the  above  process  to  a 
number  of  commercial  fluid  extracts,  results  were  obtained  as  shown 
in  the  following  table : 
No.  of  Sample. 
Sp.  Gravity. 
Per  cent,  of  Alka- 
loid extracted  from 
the  drug. 
Per  cent,  of  Alka- 
loid in  the  fluid 
extract. 
Grains  of  Caf- 
feine in  each  fluid 
ounce. 
1  
1.0227. 
2.70. 
2.69. 
12.35. 
2  
1.0182. 
2.75. 
2.70. 
12.55. 
0.9587. 
2.72. 
2.84. 
12.44. 
0.9947. 
2.93. 
2.94. 
13.36. 
0.9536. 
2.99. 
3.13. 
13.67. 
6  
1.0409. 
3.57. 
3.42. 
12.29. 
7  
0.9848. 
3.40. 
3.45. 
15.51. 
8  
0.9797. 
3.52. 
3.60. 
16.08. 
9  
0.9508. 
3.70. 
3.89. 
16.88. 
102  
1.0515. 
4.85. 
4.61. 
22.13. 
Average  
0.9856. 
3.31. 
3.33. 
15.03. 
"The  National  Dispensatory"  (3rd  edit.  p.  366)  credits  E.  Hosack, 
(1883),  (the  writer  has  not  been  able  to  consult  the  original  paper) 
with  the  statement  that  commercial  fluid  extracts  of  guarana  yielded 
only  1.10  per  cent,  to  1.68  percent  of  caffeine,  while  it  will  be  seen 
that  the  average  of  the  above  fluid  extracts  is  3.33  per  cent,  or  prac- 
tically, double  the  highest  estimate  given  by  Mr.  Hosack.  The  experi- 
ments of  J.  H.  Feemster,  already  referred  to,  show  that  guarana 
1  Specific  gravity  was  taken  at  the  temperature  of  the  work  room  (26°  C.) 
compared  with  water  at  the  same  temperature. 
2  This  was  a  fluid  extract  which  had  evidently  been  standing  for  a  consider- 
able length  of  time  in  a  nearly  empty  bottle,  which  probably  accounts  for  its 
unusual  strength. 
