ON  THE  DESTRUCTION  OP  NOXIOUS  INSECTS. 
73 
bugs,  fleas,  and  flies  disappear  from  houses  under  its  influence. 
As  to  manufactured  articles,  the  powder  is  applied  effectually 
to  the  following  : — 
1.  Furs. — These  require  great  care  for  their  preservation. 
Numerous  insects  live  upon  them.  Their  propagation  is  rapid. 
The  only  remedy  against  their  ravages  hitherto  has  been  pepper 
or  camphor,  but  by  using  the  powder  of  Pyrethrum  the  insects 
and  their  larvae  will  be  most  effectually  destroyed. 
2.  Feathers. — The  same  result  will  be  arrived  at  by  using 
this  powder  for  the  prevervation  of  the  costly  products  of  fea- 
ther dealers.  Most  woollen  products  have  also  a  number  of  in- 
sect enemies,  especially  in  their  undeveloped  state,  as  larvae. 
The  powder  of  Pyrethrum,  if  applied  in  proper  time,  will  effec- 
tually preserve  all  woollen  articles.  Natural  history,  too,  has 
its  share  of  the  advantages  afforded  by  this  powder  in  the  pre- 
servation of  collections  of  mammalia,  birds,  fishes,  reptiles,  in- 
sects, and  anatomical  preparations. 
Herbariums  are  very  frequently  devastated  by  insects  gradually 
piercing  the  paper  as  well  as  the  dried  plants,  reducing  the 
latter  almost  to  a  powder,  more  especially  if  they  have  not  been 
poisoned  by  chloride  of  mercury  dissolved  in  alcohol — a  sub- 
stance both  expensive  and  dangerous.  By  applying  a  pinch  of 
the  powder  between  the  leaves  of  his  herbarium,  the  botanist 
will  soon  get  rid  of  the  enemies  of  his  collection.  Finally,  a 
most  important  advantage  of  this  powder  is  that  it  is  innocuous 
to  man,  and  can  be  absorbed  by  the  human  subject  without  the 
slightest  danger  to  his  health.  Some  physicians  of  celebrity 
even  assert  that  the  powder  can  be  advantageously  sprinkled 
upon  sores  or  open  wounds  that  diffuse  an  unpleasant  odor. 
Mode  of  applying  the  Powder. — In  using  the  powder  it  must 
be  applied  carefully  and  in  sufficient  quantity,  otherwise  the  result 
will  be  unsatisfactory,  especially  if  used  against  some  of  the 
hardy  or  very  resisting  species  of  insects.  Occasionally  the 
powder,  by  being  exposed  to  the  air  or  moisture,  will  have  lost 
its  destructive  properties,  so  as  to  render  the  result  doubtful  and 
wholly  inefficient ;  at  others  the  result  has  been  unsatisfactory, 
because  the  most  favorable  moment  for  the  operation  has  been 
overlooked.  A  rainy  or  wet  day,  for  instance,  always  lessens 
the  destructive  efficacy,  because  the  powder,  containing  a  very 
