ON  BORON. 
389 
from  the  retort  during  its  formation,  and  on  the  vapors  being 
prevented  from  condensing  in  the  upper  part  of  the  retort ;  for 
in  this  case  it  is  impossible  to  avoid  the  fusion  of  the  crystals 
and  the  flowing  down  of  the  fused  pyrogallic  acid  into  the  belly 
of  the  retort  in  which  it  is  decomposed.  The  current  of  carbonic 
acid  serves  to  avoid  this  source  of  loss,  but  it  also  effects  another 
object.  In  the  current  of  gas  the  water  formed  retains  its  vapor- 
ous form  at  those  places  in  the  neck  of  the  retort  on  which 
crystals  of  pyrogallic  acid  are  deposited  ;  in  the  receiver,  where 
vapors  of  pyrogallic  acid  and  water  condense  simultaneously,  a 
syrupous  aqueous  solution  is  obtained  instead  of  the  crystals ; 
from  this,  pyrogallic  acid  may  be  produced  by  evaporation, 
although  never  colorless. 
It  would  be  most  advantageous  to  heat  the  gallic  acid  in  a 
bath  of  constant  temperature  ;  this  can  never  be  attained  by  a 
sand-bath  placed  over  a  furnace,  and  the  current  of  gas  must 
therefore  be  regulated  according  to  the  temperature.  Thus  if 
drops  of  fused  pyrogallic  acid  are  deposited  in  the  upper  part  of 
the  retort,  the  heat  must  be  increased  and  the  current  of  gas 
slackened. 
When  the  decomposition  is  going  on,  the  wide  neck  of  the 
retort  becomes  filled  very  rapidly  with  long,  broad,  fiat,  shining, 
white  needles,  which  are  removed  with  a  feather.  If  the  neck 
of  the  retort  reaches  the  temperature  of  fusion  of  pyrogallic  acid, 
it  runs  together,  and  solidifies  lower  down  into  a  solid  crust, 
which  is  removed  with  a  silver  spatula  ;  during  fusion  the  acid 
acquires  a  reddish  color,  which  persists  after  solidification  and 
cannot  be  got  rid  of  by  charcoal.  By  this  method,  31-32  per 
cent,  of  solid  crystallized  pyrogallic  acid  are  obtained  ;  the  8-9 
per  cent,  which  are  lost  according  to  the  above  calculation,  give 
the  carbonic  acid  evolved  the  appearance  of  a  white  smoke,  and 
probably  by  a  judicious  arrangement  of  the  apparatus  some  por- 
tion of  it  might  be  recovered. — Chem.  Qaz.,  April  1,  1857, 
from  Liebig's  Annalen,  January  1857. 
ON  BORON. 
By  MM,  Woiiler  and  Sainte-Claire  Deyille. 
Most  of  the  simple  bodies,  at  least  those  which  have  been 
more  completely  examined,  present  themselves  under  interesting 
