A™ctob£^mm'}       Alkaloidal  Assays  of  the  U.S.P.  455 
adhering  of  drug  particles  to  the  sides  of  the  first  vessel  could  be 
completely  eliminated  by  carrying  out  the  shaking  and  the  perco- 
lation in  one  and  the  same  vessel  specially  constructed  for  that 
purpose.1 
(3)  As  these  drugs  are  rather  poor  in  alkaloid,  at  least  20 
grammes  of  the  leaves  or  the  root  ought  to  be  taken  for  the  assay. 
Cinchona. — Instead  of  "  a  mixture  of  125  c.c.  of  ether  and  25  c.c. 
chloroform  "  the  directions  ought  to  be  "  150  c.c.  of  a  mixture  of  5 
volumes  of  ether  and  I  volume  of  chloroform  previously  prepared 
and  cooled  to  the  ordinary  temperature."  As  on  mixing  ether  and 
chloroform  there  is  a  rise  in  temperature  and  contraction  of  volume,2 
the  100  c.c.  drawn  off  afterwards  at  ordinary  temperature  for  the 
assay  will  from  both  causes  represent  more  than  10  grammes  of 
drug. 
It  seems  to  me  that  it  would  be  better  to  use  for  the  assay  of 
cinchona  the  same  method  which  is  used  for  belladonna  root  and 
thus  avoid  taking  an  aliquot  part  of  ethereal  liquid. 
The  pharmacopoeia  directs  to  make  up  the  final  liquid  to  50  c.c. 
and  use  half  for  the  estimation  of  total  alkaloids,  the  other  half  for 
that  of  quinine.  It  would  be  more  convenient  to  pipette  off  20  c.c. 
(representing  4  grammes  of  drug)  for  each  of  these  estimations.  As 
the  drug  is  quite  rich  in  alkaloids  there  is  no  disadvantage  in  work- 
ing upon  4  instead  of  5  grammes  of  it. 
Coca. — The  percolation  ought  to  be  carried  to  exhaustion  as 
indicated  by  Mayer's  reagent,  and  by  using  the  special  tube  men- 
tioned under  belladonna  the  transferring  of  ethereal  liquid  from 
vessel  to  vessel  could  be  avoided. 
Colchici  Cormus  et  Semen. — The  use  of  the  shaking-tube  would 
be  advisable. 
On  comparing  the  methods  for  the  corm  and  the  seeds  it  will  be 
seen  that  in  the  case  of  the  corm  the  colchicine  before  it  is  weighed 
undergoes  an  extra  purification.  If  this  is  desirable  in  the  case  of 
the  corm  it  ought  also  to  be  used  in  the  case  of  the  seeds. 
Conium. — The  assay  method  is  very  complicated  and  will  hardly 
give  concordant  results  in  the  hands  of  different  chemists. 
Emplastrum  Belladonnae. — It  would  be  preferable  to  introduce 
the  plaster  cut  into  strips  into  a  separating  funnel  for  the  extraction 
1  See  American  Journal  of  Pharmacy,  1905,  p.  463. 
2  J.  Chem.  Soc.  Trans.,  1897,  371. 
