DISINFECTANTS  IN  ARRESTING  CATTLE  PLAGUE.  127 
ON  THE  APPLICATION  OF  DISINFECTANTS  IN  ARREST- 
ING THE  SPREAD  OF  THE  CATTLE  PLAGUE. 
Report  to  Her  Majesty's  Commissioners. 
By  William  Crookes,  F.R.S. 
(Continued  from  page  363.) 
19.  Some  disinfectants,  however  suitable  in  other  respects, 
are  too  expensive,  unsafe,  or  injurious  to  health,  to  be  used : 
such  are  bromine,  iodine,  peroxide  of  hydrogen,  hyponitric  acid, 
and  hyponitrous  acid. 
20.  The  value  of  excessive  heat  as  a  disinfectant  is  very 
great,  but  it  is  available  only  in  a  limited  number  of  cases.  It 
acts  in  two  ways.  Heat,  to  the  boiling  point  of  water,  con- 
tinued for  half  an  hour  or  more,  acts  as  an  antiseptic,  perfectly 
destroying  the  vitality  of  all  germs  of  contagion,  or  virus  cells. 
In  this  way  clothing  and  similar  substances  are  conveniently 
disinfected.  Heat,  pushed  to  destruction  in  the  presence  of 
air,  acts  as  a  disinfectant,  by  promoting  oxidation.  The  disin- 
fecting value  of  the  combustion  of  infected  substances  is  too  well 
known  to  require  further  notice. 
21.  Hydrochloric  acid  gas  (evolved  from  salt  and  oil  of  vitriol) 
is  most  irritating  to  the  respiratory  organs,  and  is  very  inferior 
in  its  action  to  both  sulphurous  acid  and  chlorine.  Besides, 
when  evolved  in  white-washed  sheds,  it  unites  with  the  lime  on 
the  walls,  forming  a  highly  deliquescent  compound,  chloride  of 
calcium,  which  keeps  them  permanently  damp.  The  employ- 
ment of  a  dangerously  corrosive  body  like  oil  of  vitriol  should 
also  be  avoided. 
22.  Oil  of  tar  can  also  be  removed  from  the  list,  its  value  en- 
tirely depending  upon  the  small  amount  of  the  tar  acids  it  con- 
tains (34).  To  the  same  class  petroleum  belongs.  This  body 
has  been  used  with  considerable  success  in  Wallachia  by 
M.  Etienne  R.  Veron,  who,  in  an  interesting  pamphlet,  which 
he  has  taken  great  pains  to  draw  up  and  forward  to  this  coun- 
try, (in  the  hope  that  it  may  prove  as  useful  here  as  it  has  been 
on  his  estate),  has  given  full  details  of  the  means  he  employed 
to  extinguish  (etouffer)  the  disease,  and  then  keep  it  from  his 
farms,  in  1864. 
