172 
HAIR  AND  HAIR  DYES. 
servations  in  the  '  Journal  of  Cutaneous  Medicine.'  He  observes, 
that  the  hair  owes  its  property  of  dyeing  to  its  porosity  ;  which 
is  evidently  greater  than  its  physiological  structure  would  lead 
us  to  infer.  Another  of  its  properties,  namely,  the  presence  of 
sulphur  in  its  constitution,  renders  it  prone  to  darken  under  the 
use  of  certain  mineral  substances  ;  for  example,  lead  and  mer- 
cury, whose  compounds  with  sulphur  are  black.  Thus  if  a  weak 
solution  of  lead  or  mercury  be  brushed  into  the  hair,  a  certain 
quantity  of  the  solution  will  penetrate  the  hair,  and  a  dark  color 
will  be  produced  in  consequence  of  the  formation  of  a  sulphuret 
of  lead  or  sulphuret  of  mercury.  The  depth  of  the  shade  of 
color  will  depend  upon  the  quantity  of  sulphur  present  in  the 
hair,  and  as  red  hair  and  light-colored  hair  contain  more  sulphur 
than  dark  hair,  the  result  will  in  that  case  be  comparatively 
greater.  But  where  the  amount  of  sulphur  is  too  minute  to  pro- 
duce the  dye,  science  suggests  the  means  of  introducing  more 
sulphur,  as  is  illustrated  by  a  reversal  of  the  process,  in  the  fol- 
lowing quotation  from  a  paper  by  Dr.  M'Call  Anderson  on 
Eczema  Marginatum  : — "  During  the  treatment  I  accidently  dis- 
covered what  promises  to  be  the  most  perfect  black  dye  for  the 
hair  which  has  been  seen.  After  having  used  the  bichloride 
lotion  for  some  weeks,  I  changed  it  for  the  lotion  of  hyposulphite 
of  soda  ;  and  the  morning  after  the  first  application,  the  hair  of 
the  part  which  before  was  bright  red,  had  become  nearly  black. 
One  or  two  more  applications  rendered  it  jet-black,  while  neither 
the  skin  nor  the  clothing  was  stained.  I  saw  this  patient  a 
couple  of  weeks  later,  and  their  was  not  the  least  deterioration 
of  color ;  although,  of  course,  as  the  hair  grows  the  new  portions 
will  possess  the  normal  tint."  The  reason  of  the  escape  of  the 
epidermis,  while  the  hair  was  so  thoroughly  dyed,  is  that  it  con- 
tains no  sulphur.  Mr.  Balmanno  Squire,  in  a  commentary  on 
the  above  process,  observes  that  if  instead  of  the  hyposulphite 
of  soda  one  of  the  more  common  mordants  be  employed — say, 
for  example,  the  sulphide  of  ammonium,  "  instead  of  a  black,  a 
bright  red  color  will  result.  The  modus  operandi  of  Dr.  Ander- 
son's dye  is  this.  The  hyposulphurous  acid,  on  being  liberated 
from  the  soda,  decomposes  into  sulphurous  acid  and  sulphur. 
The  sulphurous  acid  reduces  the  bichloride  of  mercury  to  the 
