GLEANINGS  FROM   THE  GERMAN  JOURNALS 
449 
bly  consists  of  a  mixture  of  various  compounds.- — (Vol.  cxiih 
338—349.) 
On  Acrolein. — -H.  Hiibner  and  A.  Geuther  prepare  it  from  1 
part  glycerin,  with  2  parts  bisulphate  of  potassa,  by  distilling 
to  dryness ;  the  yield  is  25  to  28  per  cent,  anhydrous  acrolein, 
boiling  at  52.°4  C.  (126.3  F.)  By  treating  with  pentachloride 
of  phosphorus,  the  bichloride  of  acrolein  =C6H4C12  is  obtained, 
being  a  colorless  oily  liquid,  boiling  at  84-c4  C,  (184°  F.,)  of 
1-170  specific  gravity,  at  24-°5  C,  and  of  the  odor  and  taste 
of  chloroform.  Acrolein  yields  with  ammonia  a  solid  compound 
C12H101nO3,  in  appearance  like  coagulated  albumen,  which  most 
likely  is  an  ammonium  base.  Anhydrous  acetic  acid  combines 
with  acrolein  to  an  oily  liquid  of  1-076  specific  gravity  at  22°  C, 
possessing  a  strong  fishy  odor  and  a  very  sharp  taste. —(Vol. 
cxiv.  35—51.) 
On  the  conversion  of  Malic  and  Tartaric  Acids  into  Sue- 
cinic  Acid. — Succinic  acid  2HO,  C8H406  differs  from  malic 
acid=2HO,  C8H408  and  tartaric  acid  =2110,  C8H4O10  by  con- 
taining 20  and  40  less.  R.  Schmitt  (Ann.  d.  Ch.  and  Ph.  cxiv. 
106 — HI,)  converts  both  these  latter  acids  into  the  former  by 
saturating  concentrated  hydriodic  acid  with  pure  malic  or  tartaric 
acid,  and  heating  the  solution  in  a  sealed  glass  tube,  the  former  to 
130°  C,  the  latter  not  over  120°  C.  In  about  eight  hours  the 
reaction  is  completed.  The  liquid  or  the  crystals  are  now 
boiled  in  a  retort  with  water  until  iodine  ceases  to  pass  over  ; 
the  residue  from  evaporation  is  treated  with  a  little  ether,  to 
remove  the  last  traces  of  iodine,  and  then  recrystallized  from 
water,  or,  in  order  to  remove  some  tartaric  acid,  from  boiling 
ether.    The  crystals  consist  of  pure  succinic  acid. 
On  the  use  of  Gun-cotton. — At  ordinary  temperature,  gun- 
cotton  is  not  affected  by  nearly  all  the  strong  chemical  agents. 
Prof.  Boettger  recommends  it  on  this  account,  for  the  filtration 
of  strong  acids,  of  liquids  readily  decomposed  by  organic  sub- 
stances, &c,  for  which  purposes  it  is  superior  to  asbestos, 
granites,  glass,  &c.  He  has  employed  it  for  the  filtration  of 
nitric,  fuming  sulphuric,   nitro-muriatic  and  chromic  acids, 
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