A\ovTOi',i8H72RM'}     Gleanings  from  European  Journals.  487 
4th.  That  some  benzoin  in  the  market  contains  about  one-fourth  of 
impurities,  and  therefore  its  pharmaceutical  preparations  are  corres- 
pondingly deficient  in  strength,  unless  an  allowance  for  the  impuri- 
ties be  made. 
GLEANINGS  FROM  THE  EUROPEAN  JOURNALS. 
By  the  Editor.  . 
A  New  Form  of  Water  Air-Pump. — Herr  C.  Christiansen  sug- 
gests a  very  simple  method  of  arranging  a  Bunsen  pump  for  use  in 
filtration,  etc.,  in  the  laboratory.  The  accompanying  figure  illustrates 
the  suggested  modification.  R  R  is  a  thick  walled 
caoutchouc  tube,  and  is  firmly  attached  about  the 
water-pipe  A.  With  a  red  hot  needle  an  opening  is 
pierced  through  R  R  at  e,  and  into  this  the  bent  glass 
tube  r  r  is  passed.  If  the  water  is  now  allowed  to  flow 
through  A,  but  little  suction  is  exerted  at  r  ;  a  mercury 
column  attached,  as  is  usual  in  other  forms  of  the  water  air-pump, 
shows  an  elevation  of  not  more  than  Vr.  If,  however,  the  tube  R  R 
is  pressed  together,  as  at  b,  the  quicksilver  rises  at  once  to  26//-27// ; 
a  proof  that  by  this  device  an  almost  complete  vacuum  can  be  ob- 
tained. To  obtain  the  best  effect,  much  depends  upon  narrowing  the 
tube  at  the  proper  place,  for  the  great  increase  in  effect  manifests  itself 
only  when  this  is  done  at  a  few  points.  It  is,  however,  only  neces- 
sary to  experiment  until  the  desired  conditions  are  produced,  and 
then  to  permanently  narrow  at  the  proper  point. — Pogg.  Annalen, 
cxlvi,  155,  through  Journ.  of  the  Franklin  Institute,  Sept.,  1872. 
Oxide  of  Mercury  and  Iodide  of  Potassium. — Dr.  Carl  Jehn  ob- 
served that  an  ointment  prepared  from  lard,  water,  iodide  of  potas- 
sium and  red  oxide  of  mercury  remained  colorless.  Experiments 
made,  with  the  view  of  discovering  the  cause,  proved  that  mercuric 
oxide  is  completely  soluble  in  iodide  of  potassium,  forming  iodohy- 
drargyrate  of  potassium  and  caustic  potassa.  The  reaction  takes 
place  as  follows:  HgO+4KI+H20=2KHO+2KI,HgI2.—  Archiv 
d.  Pharm.,  1872,  Aug.,  97. 
Analysis  of  Sedum  acre,  Lin, — The  mossy  stone  crop  or  wall  pep- 
per was  analyzed  by  E.  Mylius,  who  obtained  from  it  an  alkaloid, 
4*42  per  cent,  white  wax  and  chlorophyll,         soft  acid  resin,  soluble 
