HAIR  AND  HAIR  DYES. 
171 
of  nitro-glycerin,  to  which  in  mere  power  even  it  is  not  inferior. 
This  discovery,  therefore,  can  hardly  fail  to  give  a  considerable 
impetus  to  gun-cotton,  and  to  lead  to  its  universal  adoption  for' 
mining  purposes,  as  soon  as  its  new  properties  become  generally 
known.  In  connection  with  possible  military  applications  the 
discovery  is  invaluable.  There  can  no  longer  be  any  doubt  what 
agent  should  be  employed  for  the  breaching  of  stockades  and  the 
like  ;  and  the  absence  of  all  necessity  for  the  use  of  strong  con- 
fining envelopes  will  have  an  important  bearing  on  the  employ- 
ment of  gun-cotton  for  torpedos  and  all  submarine  explosive 
operations,  besides  greatly  simplifying  mining  and  breaching 
operations  in  the  field.  We  have,  in  fact,  discovered  several  new 
advantages  to  add  to  those  which  already  had  sufficed  to  recom- 
mend gun-cotton  as  an  explosive  agent  in  preference  to  all 
others.  The  conditions  that  are  fulfilled  by  a  detonating  fuse 
in  determining  the  violent  explosion  of  gun-cotton,  under  cir- 
cumstances which  hitherto  have  been  altogether  unfavorable  to 
such  a  result,  have  been  made  the  subject  of  investigation  by 
Mr.  Abel,  and  we  hope  at  some  future  time  to  notice  the  con- 
clu^ons  at  which  he  has  arrived,  as  they  appear  to  have  a  very 
important  general  bearing  upon  the  conditions  which  regulate 
the  development  of  explosive  force,  not  merely  from  gun-cotton 
and  nitro-glycerin,  but  from  explosive  compounds  and  mixtures 
generally.  Meanwhile,  it  is  satisfactory  to  be  able  to  record 
what  has  been  done,  and  to  add  that  the  subject  is  now  occupy- 
ing much  attention  at  Woolwich  and  Chatham,  under  the  intelli- 
gent direction  of  the  department  to  which  the  discovery  is  due. 
— Chem.  News,  Dec.  4,  1868, /r(?m  Pali-Mall  Cfazette. 
HAIR  AND  HAIR  DYES. 
The  attention  which  we  called,  some  time  since,  to  the  new 
and  perfect  black  hair  dye  which  Dr.  M'Call  Anderson  lately 
incidentally  hit  upon,  produced  a  long  series  of  commentaries  from 
accomplished  dermatologists  and  others,  well  qualified  to  speak 
on  the  not  uninteresting  subject.  Mr.  Erasmus  Wilson,  a  leader 
amongst  the  professors  of  dermatology,  now  enters  upon,  and 
discusses  the  whole  question  in  a  series  of  very  interesting  ob- 
