May  7,  1896. 
JOURNAL  OF  HORTICULTURE  AND  COTTAGE  GARDENER.  423 
Mr.  A.  Shearer,  who  found  petroleum  easily  made  soluble  by 
adding  it  to  a  boiling  solution  of  softsoap,  the  latter  being  used  in 
the  proportion  of  1  lb.  of  softsoap  to  eight  parts  (pounds)  of  water, 
the  petroleum  amalgamating  with  this  solution  in  any  proportion, 
and  becoming  perfectly  soluble.  Now  soluble  paraffin,  or  petro¬ 
leum  oil,  is  a  merchantable  article,  and  has  special  value  both 
as  a  fungicide  and  insecticide.  It  also  has  a  preventive  and  repel- 
lant  effect  on  insects. 
Fig.  69.— DENDROBIUM  PALLENS. 
when  wood  and  mineral  oils,  such  as  petroleum,  is  used  alone  or 
simply  mixed  with  water.  All  the  Fir  or  Pine-tree  oils  are  effective 
against  insects,  and  it  must  be  said  injurious  to  vegetation  unless 
made  perfectly  soluble  in  water,  so  that  when  applied  to  plants  the 
stomata  are  not  interfered  with,  the  cuticle  injured,  or  the  roots 
impaired  by  the  substance  decomposing  or  perishing  in  the  soil. 
Petroleum  oil  was  first  used  in  the  United  States,  and  in 
various  forms  has  gained  considerable  repute  as  an  insecticide. 
In  the  pure  state  it  has  a  more]or  less  injurious  effect  on  vegetable 
life,  a  one  part  i  in  seventy  parts  water  being  fatal  to  many 
fungoid  pests,  and  the  faintest  sprinkling  on  Turnips  and  Onions 
renders  those  crops  safe  from  the  attacks  of  “  flies  ”  while  the  smell 
lasts.  But  in  such  a  state  the  petroleum  proves  in  the  long  run 
injurious,  because  the  oil  doe*  not  perish  or  decompose  in  the  soil, 
but  remains  in  its  natural  state,  to  the  detriment  of  vegetable  life. 
To  avoid  injury  to  plants  and  roots  petroleum  was  treated  with 
soap,  a  partial  saponification  being  effected  through  the  amalgama¬ 
tion,  or  so  called  emulsion.  This  was  much  simplified  by  the  late 
The  extract  from  quassia  chips  has  been  in  use  for  some  con¬ 
siderable  time.  To  green  and  black  fly  it  acts  as  poison,  also  to 
thrips  and  caterpillars  (in  some  case*),  and  has  no  injurious  effect 
on  vegetation,  being  a  purely  vegetable  extract  acting  as  a  narcotic. 
The  intense  bitterness  of  the  extract  is  much  disliked  by  insects, 
consequently  it  not  only  acts  as  a  remedy,  but  more  or  less  re- 
pellantly  of  insect  attacks. 
Of  other  simple  substances  mention  may  be  made  of  lemon  oil, 
which  is  got  from  the  fresh  rind  of  the  Lemon,  either  by  pressure 
or  by  distillation  with  water.  It  has  a  special  affinity  for  hydro- 
