494  Mayer's  Reagent  for  Alkaloids.        l^"^' o^t!:im^^°' 
These  equivalents  are  not  very  different  from  those  given  by  Dr. 
Lyons,  and  it  is  not  a  matter  of  very  great  consequence  which  are 
used. 
GELSEMINE. 
My  own  experience  though  limited  confirms  previous  unfavorable 
reports  on  estimations  of  this  alkaloid  by  means  of  Mayer's  reagent. 
The  end  reaction  is  far  from  being  distinct  or  satisfactory.  I  have 
only  made  one  series  of  titrations  on  known  material  and  though  re- 
sults agreed  among  themselves  fairly  well  they  differ  from  previous 
published  statements.  This  is  not  to  be  surprised  at,  for  in  addition 
to  general  unsatisfactory  results  it  may  also  be  said  that  the  commer- 
cial alkaloid  is  most  likely  a  very  variable  product.  However  I  have 
allowed  my  results  to  stand  as  they  were  obtained.  It  has  been  pointed 
out  that  phosphomolybdic  acid  will  most  likely  supercede  in  the  esti- 
mations of  this  alkaloid.^  A  table  however  is  given  for  corrections, 
etc.,  based  on  the  observation  that  in  slightly  acid  solutions  1  cc.  of 
the  reagent  precipitates — 
1  in  200  0-0109 
1  in  400  0-0090 
1  in  600  ,  0-0078 
The  precipitates  when  collected,  immediately  washed,  dried  and  weighed, 
average  about  0*205  grammes  of  alkaloid  equal  to  approximately  49 
per  cent,  alkaloid. 
Fluid  measures  15  cc,^ 
Cc.  Kequired. 
Dilution. 
Equivalent. 
3-20 
1  in  600 
•0078* 
3-57 
1  in  500 
•0084 
4-17 
1  in  400 
•0090* 
4-55 
1  in  350 
•0094 
5-10 
1  in  300 
•0098 
5-77 
1  in  250 
-0104 
6-88 
J  in  200 
-0109* 
HYDEASTINE. 
The  end  reaction  with  this  alkaloid  is  not  very  distinct  but  by  us- 
ing care  in  noting  its  end,  as  already  indicated,  duplicate  titrations  may 
iPaperread  by  the  writer  before  the  American  Phar.  Assoc.,  Sept.,  1888. 
2  Probably  best  suited  as  a  representative  of  25  cc.  of  fluid  extract  or  an 
equivalent  of  drug. 
