Magazine  of  the  School  of  Agriculture. 
67 
some  of  them  may  not  be  dark,  yet  a very 
minute  weight  is  capable  of  importing  a tint 
to  a very  large  quantity  of  material. 
The  names  of  these  substances  are  xanthophyll 
(yellow),  yellow  chlorophyll  (yellow),  blue  chloro- 
phyll (blue),  erythrophyll  (red).  According  to 
the  different  proportions  of  these  colouring  mat- 
ters the  oil  varies  in  colour;  for  instance  a 
mixtrue  of  erythrophyll  and  yellow  and  blue 
chlorophyll  gives  a brown  tint,  while  a mixture 
of  yellow  and  blue  chlorophyll  imparts  a 
greenish  hue  to  the  oil.  These  substances  seem 
to  be  combined  with  the  oils,  or  to  be  sub- 
stances of  a fatty  nature.  They  are  neither 
dissolved  nor  acted  upon  by  water,  nor  by  acids 
diluted  with  water,  when  naturally  present 
in  the  oils.  They  are,  however,  freely  soluble 
in  alchohol,  and  an  alcoholic  solution  is  not 
only  susceptible  of  being  destroyed  by  the  joint 
action  of  the  air  and  water,  but  by  very  dilute 
aqueous  solutions  of  mineral  acids,  and  by  acetic 
acid.  In  aqueous  and  alcoholic  solutions,  light 
speedily  modifies  thle  blue,  and  eventually  destroys 
all  these  colours.  ’A  solution  in  turpentine  of 
the  isolated  colouring  matters  is  also  easily  des- 
troyed. But,  on  the  other  hand,  a solution  of 
the  colours  in  melted  paraffin  wax  is  completely 
stable. 
Vegetable  oils  are  decolourised  either  partially 
or  completely  by  the  application  of  one  of  the 
following  agents  or  chemical  processes : 1.  By 
the  action  of  light,  or  by  the  joint  action  of 
light  and  air.  Prof.  Hartley,  treating  of  the 
subject  of  the  bleaching  of  oils  before  the 
Society  of  Arts,  says  that  it  is  in  the  highest 
degree  probable  that  as  oxygen  is  absorbed  by 
the  oil  and  acid  substances  produced  thereby, 
these  acids  effect  the  destruction  of  the  colouring 
matters.  It  is  remarkable  that  no  reference  is 
made  to  the  action  of  ozone  and  the  actinic  rays 
of  the  sun  which  are  acknowledged  to  be  active 
agents  in  sun  and  air  bleaching.  2.  By  treating 
the  oil  with  moderately  strong  sulphuric  acid. 
As  acid  and  oil  are  of  different  specific  gravities, 
it  is  essential  that  they  be  very  rapidly  and 
thoroughly  mixed  by  violent  agitation.  The 
impurities  such  as  mucilage  and  albumenous 
matter  are  thus  deprived  of  water  and  more  or 
less  charred,  and  along  with  them  the  colouring 
matters  are  destroyed  by  the  acid.  It  is  essen- 
tial for  the  success  of  the  process  that  the  oil 
and  the  acid  be  not  long  in  contact  without 
undergoing  dilution,  otherwise  the  oil  itself  may 
become  cliarred.  It  is  possible  to  obtain  oil  by 
this  process  in  a fairly  colourless  condition, 
after  it  has  been  thoroughly  washed  with  water 
and  allowed  to  settle.  3.  Oils  may  be  rendered 
of  a pale  yellow  and  even  almost  colourless  by 
a process  of  partial  saponification  with  caustic 
alkali  of  a suitable  strength.  The  colouring 
matters  are  saponified  and  the  resulting  soap  is 
of  a dark  yellow  or  brown  colour  from  the 
colouring  matter  having  combined  with  the  alkali. 
4.  By  the  action  of  chlorine  produced  in  con- 
tact with  the  oil  when,  for  instance,  an  aqueous 
solution  of  bleaching  powder  is  acidified  with 
a cheap  mineral  acid,  such  as  dilute  sulphuric. 
In  this  case  rapid  mixing  and  violent  agitation 
are  essential  to  the  success  of  the  processs,  other- 
wise chlorinised  products  are  retained  in  the  oil, 
Which  not  only  confer  upon  it  a distinct  flavour 
and  odour,  but  also  cause  the  oil  to  solidify 
with  a very  moderate  lowering  of  the  temperature. 
It  is  very  questionable  whether  the  “dyeing  oils” 
can  be  subjected  to  such  treatment.  A variety 
of  methods  may  be  merely  mentioned,  such  as 
treatment  with  sulphurous  acid,  ferrous  sulphate 
(green  vitriol),  and  potassium  dichromate  and 
sulphuric  acid. 
Lastly,  there  is  the  method  of  Binks,  specially 
adapted  for  decolouring  dying  oils,  such  as  linseed 
oil,  viz.,  by  means  of  oxides  of  manganese.  The 
colouring  matter  of  the  oil  forms  a compound 
with  the  manganese  which,  while  it  remains  in 
solution,  is  very  speedily  oxidised  in  contact  with 
air,  especially  when  a current  of  air  or  oxygen 
is  blown  through.  The  oxidation  destroys  the 
colouring  matter. 
GENERAL  ITEMS. 
Referring  to  betel-leaf  a Medical  Correspondent 
to  the  Indian  Agriculturist  writes  : — The  juice  is 
hot,  pungent  and  stimulant,  increases  gastric 
juice,  and  helps  digestion.  It  is  in  its  way 
antiseptic,  for  it  not  only  removes  the  feetor  of 
the  mouth,  but  increases  saliva.  It  is  useful  in 
catarrhal  affections  especially  in  children.  When 
smeared  with  mustard  oil  and  applied  to  the 
chest  it  relieves  cough  and  dispepsia  more  by 
warmth  and  exclusion  of  air  than  by  any  rubi- 
facient  effect  it  produces.  Thus  applied  it  also 
relieves  congestion  of  the  liver,  arrests  the 
secretion  of  milk,  and  resolves  glandular  swell- 
ings. Abcesses  are  induced  to  burst  when  betel- 
leaf  is  applied  with  ghee  on  one  side,  and  headache 
is  relieved  by  the  application  of  it  to  the  temples. 
The  writer  has  successfully  used  betel  juice  and 
lime  externally  in  cases  of  troublesome  cough 
resulting  from  sorethroat  and  phthisis.  The  relief 
is  said  to  be  instantaneous. 
According  to  the  Madras  Times,  the  Government 
of  India  has  indicated  its  disapproval  of  the 
policy  of  the  Madras  Government,  by  which  the 
Agricultural  and  Veterinary  department  should 
be  under  the  control  of  the  Director  of  Public 
Instruction,  and  has  hinted  that  these  depart  ments 
should  each  attend  to  its  own  proper  work. 
The  Cotton  tree,  the  native  kapok,  which  is 
very  common  in  Burmah,  is  now  said  to  be 
receiving  much  attention  as  an  article  of  culti- 
vation, and  to  be  ousting  coffee  frcm  that  province. 
The  lack  of  suitable  machinery  to  clean  the  fibre 
has  hitherto  stood  in  the  way  of  its  development 
as  an  industry,  but  that  obstacle  is  said  to  have 
been  recently  removed.  The  cotton  trees  of  Burmah 
are  of  three  species,  two  of  which  are  known 
among  the  natives  as  the  male  and  female  trees, 
and  are  very  common,  and  grow  to  a height  of 
from  80  to  100  feet.  Though  grand-look  ing  trees 
the  wood  is  soft  and  worthless,  and  the  cotton 
fibre  attached  to  the  seeds  has  hitherto  been  used 
only  for  stuffing  pillows  and  cushions.  If,  how- 
ever, the  machinery,  which  is  a Dutch  invention, 
about  to  be  introduced,  will  enable  it  to  be  spun 
into  yarn,  Burmah  will  develop  a very  important 
industry. 
The  following  note  is  taken  from  a ecent 
communication  from  the  Colonial  8ecrretary( 
