414 
INDIA-RUBBER  VARNISH. 
tions,  were  cut  at  the  end  of  December,  January,  February 
and  March.  A  disk  of  the  same  thickness  was  cut  from  each  at 
the  same  height  above  the  ground,  and  was  made  the  bottom  of 
a  vessel  filled  with  water  ;  the  sizes  of  the  vessel  and  height  of 
the  water  being  the  same  in  all.  The  first  (cut  in  December) 
allowed  no  water  to  pass  ;  the  others  passed  more  or  less  ;  that 
cut  in  January,  at  the  end  of  48  hours  ;  that  of  February,  be- 
fore the  end  of  the  second  day  ;  that  of  March,  in  two  hours. 
Two  similar  oaks  were  selected  and  felled,  the  one  at  the  end 
of  December,  the  other  at  the  end  of  January,  and  staves  made 
of  the  wood.  Barrels  were  made  of  them,  which  were  soaked  in 
the  same  way,  and  then  filled  at  the  same  time  and  with  the 
same  wine.  In  a  year  the  barrel  made  of  the  wood  cut  in  De- 
cember had  lost  0-14  quart,  while  the  other  had  lost  7-2  quarts. 
— Journ.  Frank.  Inst.,  May  1862,  from  Cosmos. 
INDIA-RUBBER  VARNISH. 
That  india-rubber  dissolved  in  various  liquids  yields  a  good 
varnish  is  well  known  ;  but  in  general  they  are  too  viscid  for 
delicate  purposes,  and  are  only  good  for  making  stuffs  water- 
proof. India-rubber  liquefied  by  heat,  dissolved  in  oil  of  coal- 
tar,  or  drying  linseed-oil,  does  not  give  a  varnish  of  sufficient 
fluency,  or  free  from  smell.  Moreover,  a  considerable  quantity 
of  india-rubber  remains  undissolved  in  a  gelatinous  state,  sus- 
pended in  the  liquid,  so  that  the  solution  is  never  clear.  Dr. 
Bolley  has  recently  published  some  remarks  on  this  subject 
which  may  be  useful.  If  india-rubber  be  cut  into  small  pieces 
and  digested  in  sulphuret  of  carbon,  a  jelly  will  be  formed ;  this 
must  be  treated  with  benzine,  and  thus  a  much  greater  propor- 
tion of  caoutchouc  will  be  dissolved  than  would  be  done  by  any 
other  method.  The  liquid  must  be  strained  through  a  woolen 
cloth,  and  the  sulphuret  of  carbon  be  drawn  off  by  evaporation 
in  a  water  bath  ;  after  which  the  remaining  liquid  may  be  di- 
luted at  will  with  benzine,  by  which  means  a  transparent  but 
still  yellowish  liquid  will  be  obtained.  A  more  colorless  solu- 
tion may  be  prepared  by  digesting  india-rubber  cut  into  small 
pieces  for  many  days  in  benzine,  and  frequently  shaking  the  bot- 
