ACTION  OF  WATER  UPON  GLASS. 
65 
ON  THE  ACTION  OF  WATER  UPON  GLASS. 
By  J.  Pelouze. 
The  author  refers  to  the  observations  of  Scheele,  Lavoisier, 
Chevreul,  and  other  chemists,  upon  the  action  of  water  upon 
glass,  but  remarks  that  no  one  has  yet  attempted  to  determine 
the  extent  of  the  alteration  thus  produced.  The  action  of  water 
upon  glass  reduced  to  powder  is  the  principal  object  of  his  me- 
moir. 
The  action  of  boiling  water  is  excessively  slow  upon  glass 
vessels  in  which  it  is  boiled,  and  when  cold  it  has  still  less  ac- 
tion, but  it  decomposes  powdered  glass  with  extraordinary  ease. 
Thus  a  bottle  of  half  a  litre  scarcely  loses  1  decigrm.  when  water 
is  boiled  in  it  for  five  whole  days  ;  but  if  the  neck  be  cut  off  and 
powdered  and  boiled  in  the  same  vessel  for  the  same  time,  it 
loses  nearly  a  third  of  its  weight.  The  same  vessel  which  has 
contained  water  for  years  without  losing  appreciably  in  weight, 
will  lose  2  or  8  per  cent,  in  a  few  minutes  by  simple  contact 
with  cold  water  when  pulverized.  The  following  are  the  results 
of  some  of  the  author's  experiments  : — 
1.  A  specimen  of  white  glass,  of  the  best  commercial  quality, 
consisting  of — 
Silica  .  72-1 
Soda       .  ....  124 
Lime   .....  15-5 
Alumina  and  oxide  of  iron  .      .  traces, 
was  very  finely  powdered  on  a  plate  of  agate  ;  5-510  grms.  were 
boiled  in  a  porcelain  capsule  with  frequently  renewed  distilled 
water.  The  clear  liquids  were  evaporated  and  the  residue  cal- 
cined ;  it  weighed  0-175. 
The  portion  insoluble  in  water  was  treated  with  water  acidu- 
lated with  muriatic  acid,  when  a  pretty  brisk  effervescence  was 
observed.  The  muriatic  acid  solution  was  saturated  with  am- 
monia, which  produced  a  slight  precipitate  (alumina),  an  excess 
of  oxalic  acid  was  added,  the  oxalate  of  lime  was  collected, 
washed,  dried,  and  decomposed  by  sulphuric  acid;  it  gave  0-190 
of  sulphate  of  lime,  representing  0-078  of  lime,  or  1-5  per  cent, 
of  the  weight  of  glass  employed.    The  glass  containing  15  per 
5 
