500  Concentrated  Solution  of  Silver  Iodide.  {A^VemberPi9™' 
it  may  be  noted  that,  besides  the  fatty  oil,  they  contain  the  crystal- 
line, cyanogenetic  glucoside,  gynocardin,  C13H1909N,  which  has  like- 
wise been  made  the  subject  of  a  complete  chemical  investigation.13 
It  may  be  remarked,  in  conclusion,  that  it  has  not  been  possible 
in  this  place  to  present  more  than  a  very  brief  survey  of  the 
above-mentioned  series  of  long,  costly,  and  exceedingly  difficult  re- 
searches relating  to  chaulmoogra  oil  and  allied  products.  The  con- 
sideration now  given  to  the  subject  would,  moreover,  have  seemed 
quite  unnecessary,  had  it  not  been  deemed  important  to  avoid,  if 
possible,  the  confusion  which  the  recently-published  paper  of  Mr. 
Chattopadhyay  is  likely  to  create  ;  for  the  various  statements  of  dif- 
ferent observers  are  not  infrequently  transcribed  in  the  literature 
without  due  discrimination  as  to  their  validity  or  any  indication  of 
their  relative  value.  The  hope  may  therefore  be  entertained  that, 
by  a  more  careful  perusal  of  the  literature  relating  to  chaulmoogra 
oil,  and  a  just  recognition  of  the  results  of  the  researches  therein 
recorded,  Mr.  Chattopadhyay  may  not  consider  it  incumbent  upon 
him  to  pursue  his  contemplated  further  study  of  the  "  constituents 
of  gynocardic  acid." 
Hudson,  N.  Y. 
SO-CALLED  CONCENTRATED  SOLUTION  OF  SILVER 
IODIDE. 
By  John  K.  Thum,  Ph.G. 
There  is  on  the  market,  at  the  present  time,  a  so-called  soluble 
preparation  of  silver  iodide.  That  is  to  say,  the  silver  iodide  is  in 
concentration  in  the  form  of  a  solution,  and  the  addition  of  this  solu- 
tion to  a  designated  volume  of  water  makes  a  5  per  cent,  suspension 
of  silver  iodide.  Whether  this  method  of  dispensing  silver  iodide 
possesses  any  advantages  over  the  usual  method  is  questionable.  In 
the  writer's  opinion,  it  would  be  far  safer  for  a  patient  to  receive  a 
freshly-prepared  precipitate  of  this  chemical,  well  washed,  and  held 
in  suspension  with  the  acid  of  a  solution  of  gelatine,  Irish  moss,  or 
some  other  appropriate  gummy  substance. 
This  solution  of  silver  iodide  is  made  by  taking  advantage  of  the 
fact  that  silver  iodide  is  soluble  in  an  excess  of  potassium  iodide. 
Joum.  Chem.  Soc,  1905,  87,  pp.  349~357 ;  1910,  97,  pp.  1285-1289. 
