Am.  Jour.  Pharm. 
July,  1915. 
Disinfection. 
319 
stances  are  not  generally  applicable  as  disinfectants.  For  purifying 
water  or  sewage  where  oxidation  of  organic  matter  is  as  important  as 
germicidal  action  the  oxidizing  agents  are  especially  adapted. 
Mercuric  chloride,  while  being  highly  efficient  under  exceptional 
conditions,  is  so  readily  destroyed  or  so  lowered  in  efficiency  under 
ordinary  conditions  that  it  is  not  a  dependable  disinfectant.  It  is 
precipitated  by  protein,  soap,  and  sulphur  compounds ;  it  is  limited 
in  its  penetrating  properties  because  of  the  coagulating  action  on 
albumin  ;  it  inhibits  the  growth  and  does  not  kill  organisms  after  short 
exposures ;  it  is  exceedingly  poisonous  and  irritating. 
Formaldehyde  is  limited  in  its  usefulness  to  its  application  as  a 
gaseous  disinfectant.  In  this  field  no  preparation  can  replace  it; 
but  a  solution  of  the  gas  in  water  applied  as  a  liquid  disinfectant 
is  far  inferior  to  phenol. 
The  comparisons  made  above  indicate  that  even  the  ordinary 
coal-tar  disinfectants  when  properly  prepared  are  superior  to  phenol 
under  all  conditions,  and  surpass  all  other  disinfectants  aside  from 
the  purposes  for  which  the  latter  are  peculiarly  adapted. 
Recently  coal-tar  disinfectants  of  much  higher  efficiency  have 
been  prepared.  The  coefficients  of  some  of  these  in  fact  are  so  high 
that  the  correctness  of  such  statements  is  seriously  questioned.  The 
origin  and  chemical  character  of  the  oils  from  which  these  are  pre- 
pared are  more  or  less  indefinite.  Whether  the  character  of  the  coal 
or  the  method  of  distillation  by  which  the  oils  are  produced  is  respon- 
sible for  the  high  germicidal  value  is  not  generally  known.  That  it 
is  not  produced  in  America  might  indicate  that  the  character  of  the 
coal  is  at  least  partly  responsible  for  the  difference.  The  methods 
used  in  producing  gases  from  coal  for  use  in  the  steel  and  iron  indus- 
tries differ  in  England  from  those  followed  in  America.  It  is  a  well- 
known  fact  that  the  temperature  maintained  and  the  presence  or 
absence  of  air,  during  the  destructive  distillation,  very  markedly 
influence  the  character  of  the  resulting  products.  In  one  case  the 
benzols  appear  to  oxidize  to  phenols,  in  another  they  appear  to  polym- 
erize to  naphthaline,  anthracene,  etc.  This  being  true,  it  may  be  that 
still  another  series  of  compounds  results  from  a  slight  difference  in 
the  conditions  obtaining  during  this  destructive  process.  The  chemi- 
cal composition  has  been  claimed  by  Worrall  (Rideal's  "  Disinfection 
and  Disinfectants  ")  to  be  such  as  to  place  them  among  the  organic 
compounds  that  are  entirely  different  from  the  phenols  of  coal  tar. 
