28 
GLEANINGS  FROM  FOREIGN  JOURNALS. 
formula  C14H3Ag012-j-2HO.  It  forms  by  a  molecular  change 
in  the  crystals  of  the  basic  salt,  "which  is  obtained  by  precipi- 
tating the  salt  of  an  alkali  with  nitrate  of  silver,  and  recrystal- 
lizing  from  a  solution  in  dilute  nitric  acid.  The  tri-basic  salts 
of  this  acid,  which  form  on  treating  those  containing  two  equi- 
valents of  the  base  with  an  alkali,  possess  a  yellow  color. 
The  acid  crystallizes  "with  3  eq.  of  water  for  every  two  of 
acid.  It  effloresces  in  the  air,  and  loses  the  whole  of  its  water 
of  crystallization  over  oil  of  vitriol  or  at  212°  F.  Heated  to 
292°  F.,  it  again  loses  water ;  at  428°  F.,  it  turns  greyish  and 
gradually  still  darker,  and  fuses  with  much  frothing  (from  the 
escape  of  over  40  per  cent,  of  carbonic  acid)  to  a  black  mass, 
and  a  crystalline  sublimate  fusible  at  136°  F.  The  black  resi- 
due contains  an  acid  nearly  corresponding  to  the  formula  C30 
H14028,  which  is  soluble  in  water,  but  insoluble  in  alcohol. 
Strong  sulphuric  acid  destroys  chelidonic  acid  on  application 
of  heat ;  the  other  mineral  acids  do  not  appear  to  act  on  it. 
Treated  with  excess  of  bromine  in  the  presence  of  water  at  a 
moderate  heat,  decomposition,  without  evolution  of  gas,  takes 
place.  Hydrobromic  acid  is  formed,  a  heavy  oil  remains  in 
the  retort,  and  another  oil,  heavier  than  water,  passes  over 
with  the  vapors  of  water.  The  residuary  oil  crystallizes  in 
colorless  radiating  crystals  from  an  ethereal  solution ;  these 
have  the  composition  of  pentabrom  acetone,  C6HBr502,  from 
which  it  differs  only  by  its  fusing  point  being  much  higher,  and 
its  greater  resistance  to  the  action  of  heat.  The  residuary 
liquid  likewise  contains  oxalic  acid.  The  heavy  liquid  which 
passes  over  appears  to  be  hromoform. 
An  apparatus  for  the  fractional  distillation  of  bituminous 
coals,  shale  and  mineral  oils,  etc.,  has  been  contrived  by  Reg- 
nault  for  the  use  of  the  French  Customs  and  manufacturers,  and 
is  described  in  Annales  de  Chimie  et  de  Physique,  Tome  68, 
p.  409,  and  Fresenius'  Zeitschrift  fur  Analytische  Qhemie, 
1864,  p.  357.  Here  it  is  used  by  the  rectifiers  of  petroleum, 
and  is  for  sale  by  Luhme  k  Go.  in  New  York. 
The  apparatus  consists  of  a  small  upright  cylindrical  copper 
still,  with  a  tubulus  on  top  for  the  introduction  of  the  oil,  and 
for  the  insertion  of  a  cork  with  a  thermometer  for  determining 
the  boiling  point.    The  beak  is  a  narrow  tube  soldered  to  the 
