ASSAY  OF  ALKALOIDS.  T 
appeared  in  this  Journal.  I  there  distinctly  compare  their 
composition  with  that  of  Hinterberger's  double  chlorides  of  the 
same  alkaloids,  which  probably  present  the  only  analogy  in  that 
class  of  compounds.  As  to  atropia,  I  have  never  written  such 
a  formula  as  Mr.  Groves  pretends  to  copy  from  me.  It  is  evi- 
dently deduced  from  the  formula  for  morphia  of  September,  1863, 
while  my  assay  of  atropia  was  written  in  December,  1862,  and 
appeared  in  your  January  number  of  1863. 
The  truth  is,  that  in  the  paper  last  quoted  I  did  not  publish 
any  formula  whatever  ;  but  what  Mr.  Groves  alludes  to  is  a 
line  in  the  first  part  treating  on  alkaloids  generally,  where  I 
use  the  following  words  :  «  The  compounds  formed  are  the  hy- 
driodates  of  the  bases  with  iodide  of  mercury."  I  was  not  in- 
debted to  Mr.  Groves  for  this  information  ;  it  was  my  own  view 
of  their  constitution,  which  was  strengthened  by  that  of  Boe- 
decker's  compound  of  nicotia.  But  it  would  be  strange  if  Mr. 
Groves  could  not  tell  what  caused  me  to  give  expression  to  this 
phrase.  Must  I  recall  that  in  his  first  paper  (published  on  page 
97  of  Vol.  xi.  of  the  Journal  of  the  Chemical  Society^,  his  for- 
mula was  not  what  it  is  now,  but  alkaloid  +  sesqui-iodide  of  mer- 
cury, viz.,  Alk.-j-  Hg2rs?  Well  was  it  then  for  me  to  state  that 
they  are  the  hydriodates  of  the  bases  with  iodide  of  mercury,  and 
I  did  so  at  the  time,  not  in  the  least  acquainted  with  the  able 
manner  in  which  Mr.  J.  Dyson  Perrins  had  previously  handled 
Mr.  Groves'  assumptions  in  the  later  pages  of  the  Pharmaceu- 
tical Journal,  (Vol.  xiii.  pp.  241  and  340.) 
I  come  next  to  a  personal  matter,  which  I  believe  will  now 
be  understood  in  its  true  light. 
My  critic  attacks  my  mode  of  assaying  the  residual  liquid 
with  silver,  and  (in  italics)  throws  out  the  suggestion  that,  in 
my  assay  of  atropia,  I  have  been  guilty  of  recording  a  falsehood. 
I  grant  that  if  any  chemist,  whether  personally  acquainted  with 
me  or  not,  can  be  made  to  believe  of  me,  to  what  the  argument 
leads,  that  after  stating  at  the  head  of  the  paragraph  the  exact 
quantity  of  reagent  required,  I  could  have  used  four  times  that 
quantity,  and  having  found  that  I  had  done  so  in  one  experi- 
ment, could  have  been  guilty  of  doing  the  same  over  and  over 
again,, — then  I  stand  convicted.  Bent  upon  discovering  errors, 
he  reads  residuary  silver  for  combined  halogens,  and, — here  is 
