76 
RENDERING  STUFFS  WATER-PROOF. 
SIMPLE  PEOOESS  FOR  RENDERING  STUFFS  WATER- 
PROOF. 
M.  Thieux,  of  Marseilles,  proposes  the  following  simple  pro- 
cess for  rendering  stuffs  water-proof. 
In  two  vessels,  each  of  a  content  of  12  gallons  of  river  water 
are  dissolved,  in  the  one  3j  lbs.  of  alum,  in  the  other  the  same 
weight  of  sugar  of  lead.    When  the  solutions  are  complete,  pour 
the  liquids  together,  by  which  will  be  formed  an  insoluble  sul- 
phate of  lead,  and  soluble  acetates  of  alumina  and  potassa,  mixed 
with  a  slight  excess  of  alum.    As  soon  as  the  liquid  has  become 
clear,  it  is  drawn  off  and  the  stuffs  plunged  into  it ;  they  must 
be  strongly  compressed  while  under  the  liquid  to  expel  the  air 
from  their  pores,  and  then  suffered  to  soak  for  at  least  four 
hours,  so  as  to  insure  the  perfect  penetration  of  the  liquid  every- 
where.   When  withdrawn,  they  are  lightly  shaken,  then  dried, 
brushed,  and  pressed  with  a  hot  iron.    It  appears  that  various 
specimens  of  cloth  experimented  on  by  the  Committee,  absorbed 
from  11  to  17  per  cent,  of  their  weight  of  saline  matters,  and  re- 
tained their  original  appearance,  and  their  pliability  at  all  tem- 
peratures.   But  after  immersion  in  fresh  water  for  24  hours,  they 
lost  all  their  additional  weight.    As  to  the  efficacy  in  this  pro- 
cess, there  appears  to  be  a  very  serious  difference  of  opinion ; 
the  conclusions  of  the  Committee  appointed  to  examine  it,  as  re- 
ported by  M.  Jacquelain,  are  that  it  is  not  new,  nor  as  good  as 
was  announced  ;  but  it  had  been  tried  and  approved  for  five 
years  by  the  Lyons  and  Mediterranean  Railroad  Company  ;  that 
the  Committee  could  not  tell  whether  it  was  durable  or  not :  its 
cost  was  about  20  cents  for  water-proofing  a  coat  or  pair  of 
pantaloons.    On  the  other  hand,  M.  Balard,  known  to  all  as  one 
of  the  most  distinguished  and  careful  chemists  of  France,  reports 
that  the  thinnest  woollen  cloths  impregnated  with  it,  are  totally 
impermeable  to  water  after  weeks  of  contact'  with  it ;  that  the 
water  evaporates  from  them  and  does  not  pass  through ;  that 
cloths  which  had  been  soaked  for  48  hours  in  fresh  water,  were 
as  impermeable  afterwards  as  before ;  that  cloths  rendered  water- 
proof in  this  way,  and  exposed  on  wicker-frames  to  the  rains  of 
October,  never  allowed  a  drop  of  water  to  pass  ;  that  a  cloak  of 
cloth  thus  prepared,  stretched  over  a  willow  frame,  and  exposed 
