64 
Nascent  Silver  Iodide, 
f  Am.  Jour.  Pharm. 
I    February,  1900. 
poisonous  action  of  these  plants  is  practically  identical  with  that 
of  the  Rhus  vernicifera,  his  work  is  of  special  interest  in  this  con- 
nection. He  has  conclusively  proven  that  the  poisonous  principle 
of  poison  ivy  is  non-volatile,  thus  shattering  the  false  idea  that  has 
existed  for  so  many  years.  He  claims  to  have  separated  the  poisonous 
principle  in  a  pure  form  by  fractional  precipitation  with  lead  acetate 
as  an  oil.  Dr.  Pfaff  gives  the  composition  of  his  lead  compound  as 
C21H30O4P7  and  proposes  the  name  "  Toxicodendrol  "  as  the  name  of 
the  poisonous  principle.  The  poisonous  principle  of  Japanese  lac 
is  so  intimately  associated  with  the  resin  of  the  lac  that  I  have  not 
considered  the  method  of  fractional  precipitation  to  be  a  complete 
separation.  Preceding  investigation  indicates  that  the  poisonous 
principles  of  these  plants  are  identical,  but  further  investigation  is 
necessary  before  this  can  be  accepted  as  conclusive.  I  hope  during 
the  coming  year  to  separate  the  poison  from  both  these  plants  and 
determine  their  relation.  Also  to  separate  the  poison  from  Japanese 
lac  in  a  pure  condition. 
The  present  researches  in  Japanese  lac  were  undertaken  in  the 
Laboratory  of  the  Pharmaceutical  Institute  of  Bern  under  the  guid- 
ance of  my  most  highly  esteemed  director,  Prof.  Dr.  A.  Tschirch. 
To  him  and  also  to  Prof.  Dr.  Oesterle  I  desire  to  express  my  warmest 
and  sincerest  thanks  for  the  inspiration  and  the  friendly  interest  and 
advice  which  has  ever  been  so  freely  and  so  kindly  given. 
The  lac  for  this  investigation  was  kindly  presented  by  forester 
Shirasawa,  of  Tokyo,  Japan,  and  the  Rhus  Company,  Frankfort, 
Germany.    To  them  I  extend  sincere  thanks. 
Ann  Arbor,  Mich. 
NASCENT  SILVER  IODIDE. 
By  M.  I.  WlIvBERT, 
Apothecary  at  the  German  Hospital,  Philadelphia,  Pa. 
Something  more  than  a  year  ago  one  of  the  physicians  connected 
with  the  out-patient  department  of  the  German  Hospital,  Philadel- 
phia, requested  the  assistant  apothecary,  Mr.  John  K.  Thum,  to 
compound  a  prescription  composed  of  5  grammes  of  a  proprietary 
silver  salt  and  I  gramme  each  of  iodine  and  potassium  iodide,  with 
a  sufficient  quantity  of  water  to  make  100  c.c.    This  mixture  was 
