AljanTuary,Pi9i8m' )    Hydrofluoric  Acid  in  Glass  Industry. 
2.  At  the  primary  operation  all  wound  surfaces  should  be  covered 
and  all  crevices  filled  with  the  20  per  cent,  solution.  Subsequent 
dressings  are  made  with  the  7V2  per  cent,  solution. 
3.  Before  the  oil  is  applied  the  surfaces  of  the  wound  should  be 
as  dry  as  possible ;  free  from  blood  and  water. 
4.  Drainage  should  be  avoided  in  all  wounds  closed  by  suture. 
5.  It  has  been  suggested  that  with  local  infections,  such  as  boils, 
carbuncles  and  abscesses,  an  incision  made  somewhat  earlier  than 
usual  with  the  free  application  of  the  20  per  cent,  solution  of 
dichloramin  T.  will  frequently  sharply  limit  the  progress  of  the  in- 
fection. 
6.  This  preparation  is  essentially  non-irritating  unless  confined 
by  unduly  heavy  or  impervious  dressings.  If  so  confined,  it  may 
blister. 
In  conclusion  I  wish  to  acknowledge  the  cooperation  of  Drs.  P. A. 
Lewis  and  W.  E.  Lee,  and  also  the  chemical  assistance  of  Miss 
Elizabeth  Hill. 
December  4,  1917. 
THE  USE  OF  HYDROFLUORIC  ACID  IN  THE  GLASS 
INDUSTRY. 
By  Johx  Gleichman. 
For  polishing  lead,  potash,  soda  and  lime  glass,  hydrofluoric  acid 
of  60  per  cent,  strength  is  necessary.  There  is  no  set  formula  for 
treating  the  glass,  all  attending  successes  depending  largely  upon 
the  temperature  at  which  the  acid  is  used,  i.  e.,  90 0  F.  This  tem- 
perature should  not  be  exceeded,  on  account  of  melting  the  wax, 
which  acts  as  a  coating  and  protects  that  part  of  the  blank  not  to 
be  polished. 
Lead  or  Potash  Glass. — The  best  results  are  obtained  by  pie- 
paring  the  dipping  acid  in  a  lead  water  rim  tank  surrounded  by  water 
bath — 900  F.  To  the  hydrofluoric  acid  continue  to  add  oil  vitriol 
gradually  until  contact  is  obtained :  a  white  coating,  referred  to  as 
mud  (silico  fluoride),  forms,  indicating  that  the  acid  solution  is  ready 
for  use.  Its  operation  depends  entirely  with  the  dipper  as  to  the 
required  number  of  immersions  (1,  2  or  3) — one  dip  of  12/15 
seconds  in  newly  prepared  acid  in  some  instances  gives  satisfaction, 
