430 
ALTERATION  OF  SUGAR  DISSOLVED  IN  WATER. 
The  fluid  is  then  ready  for  use  as  a  writing  ink  or  wood-stain.  It 
has  a  beautiful  violet-blue  color,  as  may  be  seen  from  the  thin 
stratum  which  runs  down  the  glass  when  the  bottle  is  shaken,  but 
when  rubbed  upon  wood  it  produces  pure  black.  It  may  be  pre- 
pared, even  on  a  small  scale,  at  the  price  of  threepence  per  quart. 
When  the  extract  of  logwood  cannot  be  obtained,  the  prepara- 
tion is  rather  more  tedious.  In  this  case  4  lbs.  of  logwood  may  be 
extracted  by  boiling  with  water  for  about  an  hour,  and  the  fluid, 
separated  by  decantation  and  pressing  the  woody  residue,  evapo- 
rated to  about  3  quarts  ;  1  drachm  of  chromate  potash  is  then  dis- 
solved in  it.  The  author  has  obtained  remarkably  good  results  in 
staining  wood  with  a  fluid  prepared  in  this  manner ;  but  when  it 
stands  for  a  time,  it  deposits  a  considerable  quantity  of  black  sedi- 
ment, which  shows  that  it  might  have  more  water.  Indeed  Runge 
recommends  a  larger  quantity  both  of  water  and  chromate  of  potash 
for  the  preparation  of  his  chromic  ink.  According  to  his  receipt, 
1000  parts  of  decoction  to  be  prepared  from  125  parts  of  logwood, 
and  to  this  1  part  of  chromate  of  potash  is  to  be  added.  Perhaps 
a  proportion  lying  midway  between  this  and  the  preceding  recipe 
might  be  the  most  advisable  for  a  wood-stain,  namely,  4  lbs.  of 
logwood  to  yield  9  quarts  of  decoction,  to  which  half  an  ounce  of 
chromate  of  potash  may  be  added. 
The  commercial  extract  is  however  to  be  preferred,  as  with  it 
the  preparation  is  made  very  quickly  and  with  little  trouble. — 
Chem.  Gaz.  July  2,  1855,  from  Mittheil  des  Gewerbevereins  fur 
Hannover,  1854,  p.  298. 
ALTERATION  OF  SUGAR  DISSOLVED  IN  WATER. 
E.  Maumene*  has  found  that  cane  sugar  experiences  the 
same  change  into  uncrystallizable  sugar,  when  kept  for  a  long 
time  in  solution,  as  when  heated  with  acids.  A  crystal  of  pure 
sugar  dissolves  in  boiling  potash  without  any  coloration  ;  but  a 
solution  of  the  same  sugar  after  being  kept  for  any  consider- 
able time  becomes  brown  when  boiled  with  potash,  thus  showing 
that  the  sugar  has  undergone  change.    The  progress  of  this 
*Comptes  Rendus,  xxxix.,  914. 
