6oo  Mixture  for  Writing  on  Glass.  {^""'itc^Jf- 
of  the  iron  was  also  found  to  be  present  in  iht  ferrous  state,  the  exact 
amount  of  which  was  not  determined.  It  is  the  intention  to  continue 
this  investigation  and  to  extend  it  to  the  examination  of  the  tincture  of 
ferric  chloride. 
MIXTURE  FOR  WRITING  ON  GLASS. 
By  F.  L.  Slocum. 
Read  at  the  Pharmaceutical  Meetings  No'V.  i6th. 
A  preparation  for  writing  on  glass  has  lately  come  upon  the  market 
under  the  comprehensive  name  of  "  Diamond  Ink."  It  is  to  be  used 
with  a  common  pen  and  at  once  etches  a  rough  surface  on  the  parts  of 
gkss  it  comes  in  contact  with.  It  proves  to  be  a  very  useful  article 
for  labeling  bottles  which  are  to  contain  liquids  that  will  destroy  com- 
mon labels. 
At  the  request  of  Professor  Maisch  an  analysis  was  made,  which 
proved  it  to  be  prepared  from  ammonium  fluoride,  barium  sulphate  and 
sulphuric  acid.  The  barium  sulphate  seems  to  act  as  an  absorbing 
medium  and  when  the  semifluid  mass  is  used  it  makes  a  white  mark 
and  prevents  the  spreading  of  the  watery  liquid  ;  it  also  seems  to  make 
the  acid  etch  a  rougher  surface. 
It  is  made  by  mixing  barium  sulphate  3  parts,  ammonium  fluoride 
I  pait  and  sulphuric  acid  a  quantity  sufficient  for  decomposing  the 
ammonium  fluoride  and  making  the  mixture  of  a  semifluid  consistency. 
The  sample  exammed  was  contained  in  a  glass  bottle  holding  nearly 
two  fluidrachms  and  which  was  thickly  coated  on  the  outside  with 
asphaltum,  on  the  inside  with  a  very  thick  stratum  of  beeswax,  and 
was  stoppered  with  a  rubber  stopper. 
It  is  claimed  by  the  manufacturer  that  the  mixture  contains  no  hydro- 
fluoric acid  and  does  not  corrode  a  pen,  but,  of  course,  it  does  corrode 
a  pen  and  hydrofluoric  acid  is  the  one  thing  that  does  the  etching. 
Any  one  making  this  mixture  and  wishing  to  keep  it  in  glass  may 
coat  the  bottle  inside  with  paraflin,  beeswax  or  rubber.  It  should  be 
prepared  in  a  leaden  dish,  and  is  preferably  kept  in  a  gutta  percha  or 
leaden  bottle. 
PRACTICAL  NOTES  FROM  VARIOUS  SOURCES. 
Musk  Mixture. — L.  Virlogeux  recommends  triturating  the  musk 
with  an  equal  weight  of  sugar  into  an  impalpable  powder,  which  is 
