GLEANINGS  FROM  GERMAN  JOURNALS. 
219 
Muriatic  Acid  free  from  Arsenic. — A.  BettendorfF  observed 
that  arsenious  and  arsenic  acid  is  precipitated  from  a  sufficiently 
concentrated  muriatic  acid  by  the  addition  of  protochloride  of 
tin  ;  the  precipitate  contains  from  96  to  98*6  per  cent,  arsenic. 
After  this  precipitate  is  removed,  the  muriatic  acid  may  be  dis- 
tilled, and  is  then  absolutely  free  from  arsenic. — Ihid.,  492 — 
494. 
Reduction  of  Metallic  Oxides  hy  Hydrogen. — W.  Muller  has 
made  a  long  series  of  experiments  to  ascertain  the  temperature 
at  which  the  reduction  to  the  metallic  state  takes  place  with  dif- 
ferent modifications  of  the  same  oxide.  We  extract  only  the 
following,  as  of  particular  importance  to  the  pharmacist ;  the 
temperatures  are  in  degrees  C. :  Oxide  of  iron,  prepared  by 
heating  of  the  metal  in  the  air,  was  reduced  when  moist  at  293° 
(corrected  temperature) ;  when  quite  dry,  at  305  to  339°  ;  pres- 
ence of  nitrogen  requires  an  elevated  temperature ;  prepared 
from  oxalate  of  iron  and  moist  at  278°  j  obtained  from  the  ni- 
trate by  ammonia,  at  286° ;  previously  heated  to  redness  and 
scarcely  soluble  in  muriatic  acid,  at  the  boiling  point  of  mercury. 
Oxide  of  zinc  is  not  reduced  at  the  highest  temperature  attaina- 
ble in  glass  tubes.  Oxide  of  lead  and  red  lead  are  reduced  at 
310  to  315°  ;  peroxide  of  lead  loses  a  portion  of  its  oxygen  at 
310  to  315°.  Red  oxide  of  mercury  is  reduced  at  230,  the 
yellow  at  127°.  Oxide  of  silver  at  70  to  78°  ;  oxide  of  gold  at 
85°  ;  oxide  of  platinum  at  ordinary  temperature. 
Auric  chloride  causes  an  explosion  when  heated  to  above  200° 
in  hydrogen.  Bichloride  of  platinum  begins  to  be  reduced  at 
85°.  The  chlorides  of  silver  and  lead  were  not  affected. — Ihid., 
507,  508,  from  Poggend.  Ann.  136,  51. 
A  ^peculiar  balsam  of  Peru  has  been  met  with  by  Hager  in  the 
Berlin  commerce,  and  is  either  a  new  variety  or  an  excellent 
falsification.  It  is  more  limpid,  lighter  in  weight,  and  of  a  some- 
what different  odor  from  the  genuine.  The  mixture  of  equal 
volumes  of  concentrated  sulphuric  acid  and  balsam  congeals  at 
first  in  part  only ;  one-third  of  the  volume  remains  liquid,  but 
congeals  afterwards.  Petroleum  ether  dissolves  26,  and  benzine 
afterwards  8,  altogether  34  per  cent,  cinnamein ;  genuine  bal- 
