Am  jour.  Pharm.  |       jjses  0f  Paradichlorbenzene. 
May,  19 1 S.      *  ' 
341 
erty  of  p-dichlorbenzene,  and  the  one  upon  which  most  of  its  phar- 
maceutical uses  will  undoubtedly  be  based,  is  its  powerful  destruc- 
tive action  on  certain  lower  forms  of  life.  Galewsky,  who  studied 
the  relative  efficiency  of  many  substances  as  moth  exterminators,  re- 
ported1 that  p-dichlorbenzene  is  the  most  effective  agent  for  this 
purpose,  being  superior  to  naphthalene,  which  is  generally  used. 
Many  tons  of  p-dichlorbenzene  could,  undoubtedly,  be  disposed  of 
annually  in  the  form  of  moth-balls,  moth-powders,  moth-solutions, 
moth-paper,  etc.,  if  it  were  properly  pushed.  In  physical  properties 
p-dichlorbenzene  resembles  naphthalene  very  closely.  It  occurs  as 
transparent,  colorless  flakes,  somewhat  unctuous  to  the  touch,  and 
of  a  faint,  rather  agreeable,  camphor-like  odor.  It  melts  at  53 0  C. 
and  boils  at  1720  C,  the  corresponding  constants  for  naphthalene 
being  790  C.  and  2180  C. ;  it  is,  therefore,  more  volatile  than  the 
latter.  Besides  its  greater  efficiency  as  a  moth  exterminator,  p-di- 
chlorbenzene has  the  added  advantage  over  naphthalene  that  the  odor 
can  be  more  readily  removed  from  garments  with  which  it  has  been 
packed.  Strips  of  cloth  saturated  with  a  concentrated  solution  of 
p-dichlorbenzene  in  gasoline  and  dried,  lost  the  odor  completely  after 
several  hours  of  airing  in  the  sun.  The  writer  further  finds  that 
p-dichlorbenzene  can  be  easily  compressed  into  tablets  with  an  ordi- 
nary tablet  machine  and  that  it  can  also  be  readily  formed  into  balls 
by  melting  and  pouring  it  into  molds.  On  the  whole,  p-dichlor- 
benzene seems  excellently  adapted  for  use  as  a  moth-repellant,  and 
as  it  can  probably  be  bought  for  less  than  naphthalene  it  deserves  to 
supplant  the  latter  for  this  purpose.  The  writer  earnestly  recom- 
mends that  pharmacists  and  manufacturers  introduce  and  push  it 
as  a  moth  exterminator. 
The  effect  of  p-dichlorbenzene  on  moths  suggests  that  it  may  also 
be  of  value  in  exterminating  or  repelling  other  pests.  Dissolved  in 
benzine  or  any  other  suitable  solvent  and  applied  as  a  spray  to  the 
joints  of  woodwork,  to  clothing  which  has  been  attacked,  and  to 
other  articles,  it  may  prove  effective  against  various  insects,  bed- 
bugs, roaches,  ants,  flies,  etc.,  and  their  eggs  or  larvae.  On  account 
of  the  inflammability  of  benzine  it  may  well  be  replaced  by  carbon 
tetrachloride  as  a  solvent,  as  the  dichlorbenzene  is  very  soluble  in 
this  liquid,  as  it  also  is  in  alcohol,  ether,  chloroform  and  benzene. 
Solutions  of  p-dichlorbenzene  may  also  prove  useful  against  vermin 
on  animals  and  birds,  and  as  a  spray  for  plants. 
1Z.  Textil.  hid.,  1915,  506. 
