jOtlRNAL  OP  RORTlGtlLTUkE  AND  ROTPAOP  OARMNER. 
September  2,  1897. 
Dendeobium  Fttciiianum. 
There  are  many  growers  of  Orchids  who  are  well  acquainted  with 
the  usual  run  of  Deudrohes  of  the  various  kinds  or  sections  of  kinds, 
hut  w'ho  are  total  strangers  to  many  of  the  most  interesting  species, 
the  one  cited  above  as  an  instance.  It  has  been  in  cultivation  for 
nearly  forty  years,  yet  I  think  I  am  right  in  saying  that  it  is  not 
represented  in  one  out  of  forty  collections.  This  is  a  pity,  for  to  say 
nothing  of  the  charm  of  variety  one  gets  by  growing  the  lesser  known 
kinds,  there  are  many  of  them  that  ilower  at  a  season  when  the  bulk 
of  the  more  popular  ones  are  over. 
D.  Fytehianum  is  a  very  beautiful  plant  when  seen  in  good  order, 
and  is  far  less  trouble  to  grow  than  many  that  obtain  more  recogni¬ 
tion  at  the  hands  of  orchidists.  It  is  an  upright-growing  plant,  or 
nearly  so,  about  a  foot  in  height,  producing  its  blossoms  in  rather 
slender  racemes  from  the  apex  of  growth  after  the  manner  of 
I),  phalsenopsis,  or  the  less  known  D.  barbatulum,  with  which  it  is 
sometimes  confounded.  A  dozen  or  more  flowers  are  produced  on  each 
of  these,  individually  about  2  inches  across.  The  sepals,  petals,  and 
most  of  the  lip  are  white,  the  latter  having,  in  addition  to  a  purplish 
tint  in  the  side  lobes,  a  delicate  fringe  of  yellow  hairs  under  the 
column. 
In  growth  and  time  of  flowering  it  is  not  so  constant  as  many  other 
kinds,  but  after  a  few  seasons  it  keeps  fairly  steady  to  its  resting  and 
growing  periods.  But  no  attempt  should  be  made  by  drying  off  or 
otherwise  to  force  it  into  a  resting  or  quiet  season,  when  it  is  apparent 
by  the  swelling  basal  eyes  that  the  fluids  are  active.  On  the  other 
hand,  by  all  reasonable  means  let  the  treatment  tend  to  a  proper 
routine,  as  by  this  the  plants  are  likely  to  be  more  satisfactory  over  a 
long  series  of  years. 
It  is  a  plgjit  that  has  a  wonderful  power  of  recovering  itself  after 
ill  treatment,  and  a  batch  of  apparently  almost  dead  jilants,  when 
introduced  to  heat  and  moisture,  will  often  make  good  protrress.  The 
best  position  i'or  it  is  one  not  far  from  the  roof  glass  in  the  East  Indian 
house,  or  where  the  usual  deciduous  kmds  thrive.  Like  these  it 
abliurs  either  a  close  heavy  root  run  or  a  large  receptacle,  and  is  most 
at,  liome  in  small  hanging  baskets  or  pans,  'these  must  be  scrupulously 
clean  when  used,  as  the  ].lant  dislikes  being  disturl  ed  ;  they  should  be 
thoroughly  drained  and  grown  in  an  ojaen  but  nut  too  rough  descrip- 
tioi'i  of  compost.  Equal  parts  of  peat  and  sphagnum  moss  with  small 
nodules  of  charcoal  and  crocks  suit  it  well. 
Early  in  spring  great  care  is  necessary  with  watering,  and  it  is  then 
a  little  shade  is  rerjuired  to  jarevent  the  tender  young  shoots  scorching. 
But  even  then  too  heavy  material  must  not  be  used,  as  it  defeats  the 
end  in  view  by  making  the  growths  more  tender,  and  therefore  more 
liable  to  injury.  As  the  season  advances  the  growth,  of  course, 
becomes  more  solid,  and  only  sufficient  shading  to  prevent  injury  to 
the  foliage  is  needed.  Young  roots  are  produced  at  the  base  of  the 
shoots  when  the  latter  are  little  more  than  an  inch  in  length,  and  this 
is  the  best  time  to  renew  or  add  to  the  compost. 
I  have  before  mentioned  in  this  direction  that  top-dressing  is  not 
easily  carried  out  without  injury  to  the  smaller  rooted  IL-ndrobes, 
so  it  is  well  not  to  leave  this  part  of  the  work  to  inexperienced  or 
thoughtless  persons.  Even  with  the  best  care,  although  the  old 
material  is  removed  with  comparative  ease,  it  is  different  when  it 
comes  to  bedding  in  the  new,  many  of  the  small  roots  being  either 
bruised  or  snapped  off.  To  support  the  growths  a  few  neat  .stakes  are 
sometimes  necessary  when  repotting,  but  if  the  roots  are  plentiful,  and 
the  compost  well  tinned,  they  are  not  always  required.  Finish  the 
compost  to  a  neat  convex  line,  clipping  off  all  ragged  ends  of  peat  and 
moss,  as  these  if  left  make  it  difficult  to  determine  whether  or  not  the 
plant  is  dry  at  the  roots  as  well  as  having  an  untidy  appearance. 
All  this  class  of  Orchid  is  peculiarly  liable  to  be  attacked  by 
yellow  thrips,  once  a  formidable  foe  to  Orchids,  but  since  the  improved 
methods  of  fumigation  fortunately  less  to  be  feared.  Still  even  now 
prevention  is  better  than  cure,  and  this  consists  in  keeping  up  a  well- 
balanced  temperature,  in  which  neither  heat,  air,  nor  moisture  unduly 
predominates,  and  tlie  plants  in  good  order  at  the  roots.  It  is  the  half- 
starved  plants  that  give  most  trouble  j  keep  them  healthy,  and  insects 
are  not  much  to  be  feared. 
'I  he  typical  D.  Fytehianum,  as  described  above,  is  a  native  of 
IMoulmein,  and  the  credit  of  its  discovery  is  due  to  the  Eev.  C.  Parish, 
who  found  it  in  18G3  growing  principally  on  low  trees  in  the  vicinity 
of  water,  'i’here  is  also  a  pretty  variety  called  roseum,  which  is  of 
more  recent  introduction.  'Phis  has  bright  rosj'^  sepals  and  petals,  and 
the  same  colour  continued  about  the  front  portion  of  the  lip.  The 
base  ot  the  latter  is  a  beautiful  deep  purple  that  is  visible  through  the 
hairs,  on  the  base.  It  comes  from  rather  a  different  locality  from  the 
type,  and  was  discovered  by  Major-CIeneral  Berkeley. — H.  11.  B. 
CHEMISTRY  IN  THE  GARDEN. 
{Continued  from  page  187.) 
Chemical  Properties  of  Soil. 
Absorption.  —  We  have  already  learnt  something  about  the 
absorption  of  water  by  soils,  but  as  they  are  capable  of  absorbing 
other  substances,  we  will  devote  a  little  time  to  a  consideration  of 
what  these  are. 
One  of  the  chief  chemical  properties  of  a  moist  fertile  soil  is  its 
power  to  absorb  ammonia  from  the  atmosphere.  Heinrich  carried 
out  some  very  interesting  expeiiments,  to  see  approximately  liow 
much  ammonia  an  acre  of  land  absorbed  from  the  atmosphere  in  the 
course  of  a  year.  He  found  that  while  the  rain  only  brought  down 
to  an  acre  of  land  6  lbs.  of  ammonia  per  annum,  some  soils  were 
capable  of  absorbing  30  lbs.  from  the  atmosphere,  which  would  be 
etjual  to  about  200  lbs.  of  nitrate  of  soda.  Some  soils  have  greater 
power  than  others,  which  is  no  doubt  due  to  the  larger  amount 
of  oxides  of  iron  and  alumina  they  contain;  thus  clayey  soils  are 
generally  those  which  absorb  the  maximum  amount.  The  quantity 
and  distribution  of  ammonia  in  the  atmosphere  will  be  dealt  with 
more  fully  when  we  come  to  consider  the  air  as  a  source  of  plant  food. 
We  might  carry  out  with  ease  a  simple  experiment  to  show  that 
soils  will  absorb  ammonia.  Fill  a  3-inch  pot  nearly  full  with  sifted 
soil  and  press  it  in  moderately  firm,  then  place  the  pot  over  a  tumbler 
and  pour  ammonia  water  into  the  top  of  the  pot  until  it  runs  through 
the  hole  at  the  bottom  into  the  glass.  When  the  liquid  has  passed 
through  the  soil,  put  a  small  piece  of  unslaked  lime  into  the  tumbler, 
and  if  the  experiment  has  been  carried  out  carefully  no  ammonia  will 
be  emitted  from  the  liquid,  because  it  has  been  absorbed  by  the  soil. 
Different  soils  may  be  used  in  this  experiment,  and  by  using  the  same 
amount  of  liquid  ammonia  and  lime  the  experimenter  will  soon  learn 
which  soils  have  the  greatest  absorptive  power. 
Many  practical  gardeners  use  liquid  manure  for  occasionally  damp¬ 
ing  down  vineries  and  Cucumber  houses,  and  also  place  carbonate  of 
ammonia  in  the  evaporating  troughs,  the  idea  being  that  the  leaves 
will  absorb  the  ammonia  which  is  given  off  into  the  atmosphere,  thus 
helping  to  stimulate  their  plants.  Is  it  not  moie  probable  that  the 
so  l  in  which  the  plants  are  growing  absorbs  the  ammonia,  and  after  it' 
is  converted  into  nitric  acid  the  plants  take  it  from  the  soil  by  means 
of  their  roots  ? 
Soils  are  able  to  absorb  colouring  matter  held  suspended  in  water, 
and  also  salts  from  solutions  poured  upon  them.  Take  a  5-iuch  pot 
and  till  it  with  sifted  soil,  and  after  )  rtssing  it  down  firmly  pour  very 
gradually  about  a  pint  of  the  tlark  coloured  liquid  which  may  be 
found  running  from  the  manure  heap.  When  the  liquid  has  passed 
through  the  soil  it  runs  out  perfectly  clear,  showing  that  the  soil 
has  retained  the  colouring  matter  of  the  manure  water.  It  is  this 
retentive  property  of  soils  that  makes  them  able  to  extract  the 
sewage  Irom  the  water,  and  allows  only  the  clear  liquid  to  run  into  the 
drains,  the  sewage,  like  the  colouring  matter  in  manure  Avater,  being 
retained  by  adhesioir  to  the  soil  particles.  If  water  in  which  enough 
common  salt  has  been  added  to  make  the  liquid  taste  salty  be  poured 
upon  a  pot  filled  with  soil,  it  will  be  found  that  the  water  Avhich  runs 
through  is  almost,  if  not  quite  tasteless,  showing  that  soils  are  capable 
of  absorbing  salts. 
Soils  have  also  the  power  to  decompose  certain  salts,  in  some  cases 
retaining  only  the  acid,  while  in  others  the  acid  and  base  may  be 
retained.  As  we  shall  be  continually  using  the  words  acids,  bases, 
and  salts,  more  especially  when  we  come  to  deal  with  manures  and 
plant  nuHition,  it  Mould  be  well  to  try  and  learn  at  once  what  is 
meant  by  these  terms. 
Purchase  some  red  litmus  paper  from  a  chemist.  Place  a  piece  of 
unslaked  lime  in  some  rain  water,  and  after  allowing  it  to  stand  for  a 
few  hours  pour  off  the  clear  lime  water  into  a  glass  bottle.  Put  a 
little  of  this  into  a  saucer,  and  then  dip  the  red  litmus  paper  into 
the  liquid,  when  the  paper  will  immediately  turn  blue,  if  instead 
of  the  lime  liquid  ammonia,  caustic  irotash,  soda,  or  magnesia  had 
been  used,  the  action  of  the  litmus  paper  would  have  been  the 
same — i.e.,  it  Mmuld  turn  blue  Mffien  put  in  water  containing  any  of 
the  above-named  substances.  Une  of  the  characteristic  properties 
of  a  base  is  its  power  to  turn  red  litmus  paper  blue,  and  the  bases 
Ave  shall  have  to  deal  Avith  are  lime,  ammonia,  potash,  soda,  and 
magnesia. 
Procure  some  nitric  acid  or  hydrochloric  acid  (spirits  of  salts) 
and  pour  a  little  into  water.  In  the  acid  water  place  a  piece  of  the 
red  litmus  paper,  and  note  that  its  colour  does  not  change.  Take 
the  piece  of  blue  litmus  paper  out  of  the  lime  Avater  and  put  into  the 
water  containing  the  acid,  and  you  will  observe  that  the  blue 
