228 
ON  A  BROWN  HAIR  DYE. 
would  be  as  far  from  tlie  solution  of  our  problem  as  we  were  at 
the  commencement.  That  hyposulphite  of  lead  is  insoluble  in 
water  is  true,  but  like  many  other  precipitates  insoluble  in  water, 
it  is  readily  dissolved  by  an  excess  of  the  precipitant. 
Thus,  if  you  add  to  a  solution  of  th^ee  parts  of  acetate  of 
lead  a  solution  of  two  parts  of  hyposulphite  of  soda,  you  will 
have  a  white  curdy  precipitate  of  hyposulphite  of  lead  insoluble 
in  water  ;  but  if  to  this  you  add  ten  additional  parts  of  hy- 
posulphite of  soda  the  precipitate  will  be  redissolved,  and  a  per- 
fectly clear  solution  will  be  the  result.  This  solution,  when  ap- 
plied to  the  hair,  is  decomposed  by  absorption  of  oxygen  from 
the  atmosphere.  One  of  the  results  of  this  decomposition  is 
the  formation  of  the  dark-brown  sulphuret  of  lead.  It  is  to  the 
formation  of  this  compound  in  the  hair  that  all  lead  and  sulphur 
dyes  owe  their  efficacy. 
To  those  whose  consciences  will  permit  them  to  recommend 
such  preparations  to  their  customers,  I  submit  the  following  for- 
mula : 
R.       Acetate  of  Lead,  gij ; 
Hyposulphite  of  Soda,  ; 
Kose  (or  other  perfumed)  Water,        ^xiv  ; 
Glycerin,  fgij. 
Dissolve  the  acetate  of  lead  and  hyposulphite  of  soda  in  separate 
portions  of  the  perfumed  water,  filter  separately,  mix  the  solu- 
tions and  add  the  glycerin. 
In  a  short  time  after  it  is  made,  the  solution  will  become 
slightly  torbid.  This  may  arise  either  from  a  small  quantity  of 
air  which  is  contained  in  the  liquid,  or  (perhaps)  from  the  pres- 
ence of  a  small  amount  of  oxalic  acid  with  which  glycerin  is  said 
to  be  sometimes  contaminated.  It,  however,  soon  becomes  clear 
by  deposition  of  a  minute  quantity  of  dark  powder  (sulphuret  of 
lead)  and  remains  so,  so  long  as  the  bottle  is  kept  tightly  corked, 
I  think  it  is  quite  as  harmless  as  the  ordinary  lead  and  sulphur 
dyes,  but  this  is,  at  the  best,  only  a  left-handed  recommendation. 
If  it  is  desired  to  make  a  two-bottle  preparation,  like  one  now 
on  the  market,  (limpid,  fragrant  and  perfectly  innocuous  (?),)  as 
the  advertisements  set  forth,  all  that  is  required  is  to  put  the 
solution  of  hyposulphite  of  soda  in  one  bottle  and  the  solu- 
