jAmsept'i8Mfrm'}  Gleanings  from  the  German  Journals.  461 
of  the  other  chemicals)  it  was  noticed  that  the  former  indicated  the 
absence  and  the  latter  the  presence  of  arsenic  in  the  iron ;  the  addi- 
tion first  of  traces  of  arsenious  oxide  to  iron,  subjected  to  the  above 
test,  and  later,  quantities  as  high  aso-i  gram  arsenious  oxide  failed  to 
produce  the  reaction.  Examination  of  the  residue  insoluble  in  the 
acid  showed  the  presence  of  the  arsenic  in  the  metallic  state ;  the 
arsenic  present  in  the  iron  as  well  as  the  added  arsenious  oxide  had 
been  reduced  to  the  metallic  condition  by  the  iron  or  ferrous 
chloride  and  the  nascent  hydrogen,  hence  formed  no  volatile 
hydrogen  compound.  These  same  results,  it  was  afterwards 
found  on  looking  up  the  literature,  were  published  by  Wbhler  in 
1839,  and  must  have  been  unknown  to  the  revision  committee. 
It  was  found  that  antimony  acted  in  the  same  way  as  arsenic  in 
this  test;  the  metal  was  always  found  in  the  insoluble  residue. 
If  metallic  zinc  be  added  in  the  test  (5  gm.  zinc,  2  gm.  iron,  30  cc. 
hydrochloric  acid  and  5  cc.  water)  the  evolved  gas  will  readily  stain 
porcelain  if  arsenic  be  present. — Otto  Sautermeister,  Chemiker  Ztg.y 
1 891,  1 02 1. 
Olive  oil. — At  the  meeting  of  the  Saxony  Trade-Chemists,  Dr. 
Bach  gave  a  discourse  on  olive  oil,  stating  that  the  iodine-absorp- 
tion of  the  oil  as  published  by  Hubl  (82-8-83  per  cent.)  was  cor- 
rect for  culinary  oils,  but  the  technically  important,  strongly  acid 
last-pressings  varied  from  81-6-84-5  per  cent;  there  also  occur  in 
commerce  oils,  which  by  all  other  tests  are  characterized  as  pure, 
having  iodine-absorptions  as  low  as  79  per  cent,  (due  to  the  pres- 
ence of  cholesterin  in  larger  quantity)  and  as  high  as  89  per  cent, 
(caused  by  the  addition  of  "  denaturirungsmittel,"  i.  e.,  substances 
preventing  the  use  of  the  article  for  internal  purposes,  but  not 
interfering  with  its  use  in  the  arts,  as  oils  of  rosemary  and  turpen- 
tine). The  following  preliminary  treatment  is  recommended  for  this 
last  cl'ass  of  oils  before  taking  the  iodine-absorption:  The  oil  to  be 
examined  is  placed  in  a  water  bath  and  stirred  with  about  half  its 
weight  of  powdered  crystallized  sodium  carbonate;  the  free  fatty 
acids  react  with  the  sodium  carbonate  with  evolution  of  C09  and 
the  volatile  oils  are  dissipated  ;  after  the  completion  of  the  reaction 
the  oil  is  poured  off  from  the  soap,  washed  with  hot  water  and,  in 
case  it  becomes  turbid,  dried  in  a  drying  closet  until  it  becomes 
clear  ;  it  is  now  ready  for  a  reliable  iodine-absorption.  In  this 
treatment  it  was  noticed  that  pure  Malaga  oils  retained  their  green 
