ON  THE  USE  OF  SOLUBLE  GLASS. 
567 
of  the  glass,  and  the  wall,  after  the  finishing  of  the  painting, 
is  saturated  with  the  glass  solution  by  means  of  a  fine  syringe. 
Soluble  glass  may  be  used  for  the  painting  and  preservation 
of  metals,  stone,  wood,  paper,  and  a  number  of  fabrics.  Wooden 
floors  are  thus  not  only  made  very  hard  and  durable,  but  their 
absorption  of  oil,  ink,  &c,  is  effectually  prevented,  and  they  are 
preserved  against  all  attacks  of  the  wood-worm,  &c.  Wood,  paper, 
&c,  are  rendered  uninflammable,  particularly  if  the  glass  solution 
has  been  mixed  with  chalk,  in  which  case  the  glass  coat  is  exter- 
nally hardly  altered,  while  underneath  a  kind  of  destructive  dis- 
tillation is  going  on  ;  but  if  the  coating  has  been  of  pure  solu- 
ble glass,  this  is  apt  to  become  fused  by  the  heat  and  run  off, 
thus  exposing  the  wood  or  paper  partly  to  the  fire.  Articles 
made  of  iron,  clay,  and  many  other  metals  and  earths,  may  be 
painted  and  glossed  ;  they  are  first  painted  with  the  glass,  and 
after  this  painting  has  been  allowed  to  dry,  a  second  coating, 
consisting  of  the  paint  with  a  weak  solution,  is  applied,  and 
afterwards  coatings  of  a  concentrated  warm  solution  are  laid  on, 
until  the  articles  have  attained  the  desired  gloss. 
For  druggists,  it  is  important  to  know,  that  soluble  glass, 
with  zinc  white  or  with  blane  fix,  (precipitated  sulphate  of  baryta) 
is  very  available  for  labelling  glass  bottles,  and  that  such  labels 
are  indestructible  either  by  spirits,  oils,  or  acids.  Varnished  la- 
bels cannot  be  covered  with  this  glass,  as  it  renders  them  liable 
to  crack.  But  paper  boxes  soaked  in  a  warm  solution  of  soluble 
glass,  and  after  a  complete  drying,  painted  with  a  suitable  color 
ground  in  the  solution,  are  admirably  adapted  for  the  preserva- 
tion of  herbs,  roots,  and  most  substances  requiring  to  be  kept  ex- 
cluded from  the  changes  of  the  air. 
A  "glass  paper"  has  also  been  proposed  as  a  substitute  for 
waxed  paper,  for  the  purpose  of  covering  ointments,  cerates  and 
wrapping  up  plasters,  &c.  ;  it  is  more  elegant  and  much  cheaper 
than  waxed  paper.  Professor  Artus  uses  moderately  heavy  writ- 
ing paper,  and  puts  the  solution  of  soluble  glass  of  1,12  or  1.15 
spec.  grav.  on  with  a  brush,  renewing  the  application  after  the 
first  one  has  become  perfectly  dry.  A  stronger  solution  produces 
a  more  glass-like  covering,  but  such  paper  cannot  be  rolled  with- 
out cracking. 
