322 
Disinfection. 
Am.  Jour.  Pharm. 
July,  1915. 
for  phenol ;  a  comparison  of  the  two  toxicities  with  their  correspond- 
ing dilutions  shows  that  a  solution  of  phenol  is  sixty  times  as  toxic 
as  a  member  of  Group  3  diluted  to  an  equal  efficiency. 
The  coagulative  action  and  the  caustic  and  corrosive  properties 
of  the  three  groups  can  be  only  roughly  measured ;  these  seem,  how- 
ever, to  be  very  closely  associated  with  toxicity.  So  the  practically 
harmless  nature  of  Groups  2  and  3 — particularly  the  latter — is  evident 
from  the  chart. 
Instruments  are  not  corroded,  nor  is  there  any  irritation  to  the 
healthy  skin,  when  immersed  in  such  a  solution.  The  mucous  mem- 
brane, however,  being  more  sensitive  will  tingle  and  smart  from 
application  of  this  solution  because  of  its  alkaline  and  penetrating 
character. 
Coal-tar  disinfectants  in  general  are,  like  phenol,  unaffected  by 
alkalies.  While  their  values  are  diminished  by  organic  matter  more 
than  is  phenol,  this  is  apparently  a  slower  action  rather  than  actual 
lowered  efficiency,  since  there  is  almost  no  coagulation  of  the  organic 
matter.  In  this  case  the  fact  that  the  disinfectant  is  in  emulsified 
form  explains  its  slow  action,  because  necessarily  the  minute  globules 
of  oil  composing  the  emulsion  require  a  more  prolonged  period  to 
penetrate  moist  organic  matter,  which  tends  to  retard  penetration. 
Acids  do  not  destroy  but  do  materially  impair  the  value  of  emulsi- 
fied disinfectants  in  which  the  vehicle  is  soap.  The  same  is  true  of 
hard  or  salty  water.  It  is  easier,  however,  to  correct  these  waters 
or  replace  them  with  soft  water  with  which  to  dilute  a  disinfectant 
than  to  replace  soap  by  any  other  emulsifier  of  equal  efficiency.  Soap 
has  several  valuable  properties  in  addition  to  that  of  being  an  efficient 
emulsifier  of  coal-tar  oils.  It  is  cleansing  and  tends  to  dissolve  the 
natural,  protective,  greasy  coating  on  the  skin  and  other  surfaces. 
It  is  not  devoid  of  germicidal  action  in  itself. 
As  a  deodorant  a  coal-tar  disinfectant  has  an  action  tending  to 
absorb,  remove,  and  replace  bad  odors.  Its  real  value,  however,  is 
to  destroy  the  putrefactive  bacteria  producing  the  odors — the  only 
property  which  makes  a  deodorant  of  real  value. 
An  emulsified  disinfectant  has  been  proved  to  exceed  a  soluble 
disinfectant  even  if  the  same  constituents  and  the  same  proportion 
were  present  in  each.  This  is  shown  to  be  due  to  a  concentration  of 
the  minute  globules  of  oily  emulsion  around  the  bacteria,  the  results 
being  equivalent  to  those  from  a  considerably  stronger  solution  in 
