Am.  Jour.  Pharm.) 
November,  1910.  j 
Note  on  Silver  Iodide. 
507 
rediscovered."  Excellent  illustrations  of  a  flowering  and  a  fruiting 
branch  are  given. 
Small,  1903,  Flor.  So.  East.  U.  S.,  729.    S chmaltzia  Michauxii  (Sarg.)  Small. 
".    .    .    rarely  if  at  all  "poisonous." 
Thwaites,  1904,  Ear.  West.  Trav.,  (3)  101.    Rhus  pumila  mentioned  in  a 
translated   portion   of   Michaux's  journal.     Evidently   collected  near 
Waxsaw  Creek,  in  South  Carolina. 
Warren,  1909,  Pharm.  Jour.  (83)  531.    It  is  noted  that  some  of  the  species 
now  classed  as  poisonous  may  later  be  proved  to  be  harmless. 
Trelease,  1910,  Ann.  Rep.  Mo.  Bot.  Gard.,  (20)  11.    An  excellent  illustration 
is  given  of  Rhus  Michauxii  as  growing  in  the  Missouri  Botanical  Gardens. 
The  illustration  is  reproduced  as  a  frontispiece  to  this  paper. 
Laboratory  of  the  American  Medical  Association. 
A  NOTE  ON  THE  SO-CALLED  EMULSION  OF  SILVER 
IODIDE.* 
By  John  K.  Thum,  Ph.G. 
Pharmacist  at  the  German  Hospital,  Philadelphia. 
I  it? 
When  the  writer  first  began  to  experiment  with  silver  iodide  with 
the  object  in  view  of  obtaining  a  perfect  suspension  of  this  salt  in  a 
liquid,  he  used  the  yolk  of  fresh  eggs  with  ideal  results ;  the  precipi- 
tation of  the  silver  iodide,  obtained  by  the  reaction  between  potassium 
iodide  and  silver  nitrate,  being  allowed  to  take  place  in  the  presence 
of  the  egg-yolk.  By  adhering  to  this  method,  the  greater  part  of 
the  resulting  silver  iodide  was  kept  in  colloidal  solution. 
This  method  of  manufacture  was  discarded  though  because  of 
the  scarcity  and  expensiveness  of  eggs  at  that  time,  and  which  con- 
dition still  obtains  at  present. 
After  some  further  experiment  with  mucilaginous  substances  of 
various  kinds,  the  Mucilage  of  Irish  Moss  of  the  National  Formulary 
was  decided  upon  as  being,  next  to  the  albumen,  the  most  efficient 
and  satisfactory. 
Recently  it  occurred  to  the  writer  that  the  use  of  a  typical  colloid, 
such  as  gelatin,  would  be  productive  of  better  results  and,  accord- 
ingly, some  experimentation  with  this  substance  was  carried  on. 
Aqueous  solutions  of  a  good  quality  of  gelatin  were  made,  rang- 
ing in  strength  from  o.i  to  0.5  per  cent. ;  the  solution  of  the  gelatin 
*  Nascent  Silver  Iodide.  By  M.  I.  Wilbert,  Ph.M.,  American  Journal 
of  Pharmacy,  Feb.,  1906. 
