ON  NATURAL  ORGANIC  ALKALOIDS. 
441 
loids  and  the  determination  of  their  equivalents.  "  Observing 
with  what  facility  the  solution  of  double  iodide  of  mercury  and 
potassium  detected  the  least  trace  of  alkaloids,  the  author  was 
induced  to  examine  whether  the  resulting  combination  could  be 
exactly  defined,  and  whether  he  could  obtain  a  precipitate  invari- 
able in  weight  and  characteristic  of  each  of  them."  Such,  in 
effect,  is  the  result  he  obtained  whilst  experimenting  on  a  cer- 
tain number  of  vegetable  bases.  The  high  equivalent  of  the 
reagent  employed,  the  great  density  of  the  alkaloid  precipitates, 
their  insolubility  in  aqueous  liquids,  even  when  acidulated,  en- 
abled him  easily  to  determine,  not  only  the  composition  of  these 
precipitates,  but  the  equivalents  of  the  alkaloids  themselves. 
This  new  method  leads  M.  Valser  to  conclude  that  we  must 
revert  to  the  old  equivalents  for  quinine  and  cinchonine,  which 
are  but  half  those  since  adopted.  He  also  found  by  the  same 
means  that  quinidine  is  isomeric,  not  polymeric,  with  quinine. 
The  author  desired  to  apply  his  reagent  for  the  estimation  of 
vegetable  alkaloid  matters,  but  the  presence  of  albuminous  and 
extractive  principles  vitiated  the  results.  Further,  preceiving 
that  the  processes  used  in  these  researches,  besides  being  insuf- 
ficient, occupied  too  long  a  time,  he  successfully  modified  them 
by  combining  the  successive  action  of  the  proper  solvents  in 
presence  of  lime,  which  isolates  the  alkaloids,  and  of  tannin, 
which  assists  in  decolorising  the  liquids.  This  process,  too  long 
to  be  here  described,  greatly  shortens  the  operation,  and  iso- 
lates purer  products. 
Such  is  the  summary  of  M.  Valser's  paper.  He  has  not 
feared  to  attack  excessively  delicate  toxicological  and  chemical 
questions.  Without  diminishing  the  precision  of  Stas's  process, 
he  has,  by  extending  it,  rendered  it  applicable  to  the  research 
of  morphine.  He  has  generalised  a  valuable  reaction  to  isolate 
alkaloids  by  employing  double  iodide  of  mercury  and  potassium, 
which  precipitate  them  so  effectively.  This  reagent  has  demon- 
strated the  presence  of  some  vegetable  bases  in  certain  medici- 
nal oils.  He  has  besides  discovered  some  new  reactions  for 
distinguishing  the  principal  organic  alkalies  one  from  another. 
Then  proceeding  methodically,  he  utilised  the  valuable  iodhy- 
drargyrate  of  potash  for  the  rigorous  determination  of  the  equiv- 
alent of  alkaloids,  rectifying  some,  changing  others,  all  deduced 
