488  Mayer's  Reagent  for  Alkaloids.  {^'^'oT:i^^'^' 
to  a  number  of  alkaloids,  that  I  wish  to  again  bring  forward  in  a  pa- 
per immediately  upon  the  subject  of  Mayer's  reagent.  The  experi- 
ments which  form  the  basis  of  this  paper  have  been  performed  at  odd 
intervals  during  a  year  or  more  past,  and  were  primarily  under- 
taken with  a  view  of  familiarizing  myself  to  some  extent  with  the 
peculiarities  exhibited  by  the  different  alkaloids  on  treatment  with 
Mayer's  reagent.  The  experiments,  though  not  bringing  forward 
much  that  is  new,  may  stand  in  some  measure  at  least  as  confirmations 
of  earlier  work,  and  thus  give  increased  value  to  that  which  has  pre- 
ceded. The  method  of  interpreting  the  results  of  titrations  is  very 
simple,  and  consists,  first,  in  determining  the  titration  equivalents  for 
alkaloid  in  different  degrees  of  dilution.  Then,  when  working  on  un- 
known material,  by  holding  the  dilution  of  the  initial  fluid  always 
constant,  the  number  of  cubic  centimeters  of  reagent  required  to 
precipitate  the  alkaloid  becomes  an  index  to  the  degree  of  dilu- 
tion of  the  alkaloid,  and  thus  enables  the  analyst  to  select  the 
true  experimental  equivalent  for  calculating  the  weight  and,  finally, 
the  percentage  of  alkaloid.  The  full  details  of  calculating  the 
tables  are  most  easily  understood  by  following  out  the  actual 
on  an  alkaloid,  and  this  workis  given  for  the  sake  of  illustration 
in  the  case  of  aconitine. 
MANNER  OF  USING  TABLES. 
The  manner  of  using  the  tables  is  the  same  for  all  the  alkaloids,  and 
in  illustration  let  us  take  aconitine.  Bring  the  volume  of  fluid  con- 
taining the  alkaloid  to  the  volume  indicated  at  the  head  of  the  table, 
in  our  instance  20  cc,  titrate  with  the  reagent,  and  as  hereinafter  de- 
scribed, and  note  the  amount  required  to  completely  precipitate  the 
alkaloid.  Suppose  that  from  10  grammes  of  aconite  root  the  alkaloid 
required  4*8  cc.  reagent,  referring  to  the  first  column  of  our  table  we 
find  that  this  indicates  a  dilution  of  1  part  in  300,  and  that  the  ex- 
perimental equivalent  for  the  alkaloid  in  that  degree  of  dilution  is 
.014  then  (-014  X  4-8)  X  10=0-67  per  cent,  alkaloid.  Instead  of  4-8 
cc.  suppose  that  6'3  cc.  had  been  required.  Again  referring  to  the 
table,  we  note  that  this  indicates  a  dilution  between  1  part  in 
200  and  1  part  in  250,  and  the  equivalent  to  use  in  the  calcu- 
lation might  betaken  for  either  degree  of  dilution,  or  if  for  any 
reason  we  desired  to  split  hairs  '01415  might  be  taken  as  the 
