June  23,  1398. 
JOURNAL  OF  HORTICULTURE  AND  COTTAGE  GARDENER. 
021 
SILICO-FLUORIDE  OF  AMMONIUM. 
SILICO-FLUORIDES  — THEIR  ACTION  ON  CROPS  AND 
PESTS. 
In  order  to  understand  the  action  of  any  substance,  the  nature  of  its 
components  must  be  chemically  defined,  and  in  strict  accordance  with 
ascertained  facts.  For  these  we  are  beholden  to  the  science  which  treats 
■of  the  nature,  laws  of  combination  and  mutual  actions,  of  the  minute 
particles  of  the  different  sorts  of  matter  composing  the  earth,  and  the 
products  of  the  compounds  they  form.  Chemists  have  shown,  by  their 
investigations,  that  when  the  different  substances  found  in  the  earth  are 
submitted  to  various  methods  of  treatment,  the  great  majority  of  them 
can  be  broken  up  into  others  of  a  less  complicated  nature.  By  submitting 
all  the  rocks,  minerals,  animal  and  vegetable  substances,  to  appropriate 
processes,  what  are  called  the  chemical  elements  are  obtained.  These  are 
expressed  by  symbols,  each  corresponding  to  the  initial  letter  of  its  Latin 
name,  or  where  several  elements  have  the  same  initial,  a  small  letter  is 
attached  to  it  for  the  sake  of  distinction.  Thus  C  is  the  symbol  of  carbon, 
and  Ca  that  of  calcium.  These  symbols  are  always  understood  to  repre- 
rsent,  not  an  indefinite  quantity,  but  an  atom  of  each  element.  The  symbols 
of  compounds  are  formed  by  the  juxtaposition  of  those  of  their  elements. 
Thus — HCl  expresses  the  fact  that  this  compound  contains  single  atoms  of 
its  constituents,  hydrochloric  acid  being  a  compound  ot  one  part  of 
hydrogen  (H,  l-OO)  and  35-37  of  chlorine  (Cl,  35-37).  When  more  than 
one  atom  of  an  element  exists  in  any  compound  this  is  indicated  by  a 
coefficient  placed  after  its  symbol.  Thus  HjO  =  water  is  a  compound  of 
two  atoms  of  hydrogen  and  one  of  oxygen. 
I  give  the  foregoing,  as  the  charge  is  sometimes  made  of  the  terms 
being  of  no  use  to  practical  cultivators  without  an  explanation  of  their 
meaning,  and  also  for  the  purpose  of  inculcating  the  desirableness  to 
gardeners  of  sound  knowledge  on  the  principles  of  chemistry  as  essential 
to  successful  practice,  or  the  economical  and  profitable  production  of 
crops.  Science  is  now,  fortunately,  the  handmaid  of  horticulture,  and 
the  gardener  finds  his  handbook  of  chemistry  useful  when  its  instructions 
and  principles  are 
carried  out  in  the 
field  of  active 
operations.  I  can 
appreciate  the 
horror  with  which 
some  hard-headed 
gardeners  regard 
theoretical  horticul¬ 
ture,  which  means 
with  them  all 
theory  and  no  prac¬ 
tice  ;  but  I  cannot 
understand  why  the 
gardener,  still  rely¬ 
ing  on  his  hand 
and  on  experience, 
cannot  see  his  way 
to  add  science  to 
practice.  Technical 
education  has 
greatly  changed, 
and  instead  of  being 
based  on  mere 
book  -  learning  it 
has  become  “  Prac¬ 
tice  with  Science.” 
The  best  results 
are  obtained  where 
theory  is  illustrated 
in  practice,  and  this 
brings  us  to  the 
subject  on  those 
sound  principles. 
Fluorine. 
This  element, 
F,  atomic  weight 
19*0  0,  is  very 
widely  distributed 
indeed,  and  mainly 
known  in  combina¬ 
tion,  chiefly  as  calcic 
fluoride  (CaFg), 
and  commonly 
called  finer,  finer 
spar,  or  Derbyshire 
spar.  This  is  com¬ 
posed  of  51-3  of 
calcium  or  lime, 
and  48-7  of  fluorine. 
It  is  the  source  of 
all  the  hydrofluoric 
acid  used  in  the 
arts.  The  substance 
fluorine  has  been 
{See  page  515.)  detected  in  blood, 
milk,  and  urine  ;  in 
plants  ;  in  copro- 
lites  and  other  mineral  phosphates  ;  and  forms  an  essential  part  of  the 
bones  and  teeth  of  animals.  We,  therefore,  have  it  in  solid  and  liquid 
fertilisers,  in  bonemeal,  ground  phosphates,  and  in  superphosphates.  It 
means  we  use  it  as  manure,  and  its  action,  so  far  as  I  can  make  out,  is 
decisively  anti-fungoid,  for  I  find  cereals  strengthened  in  the  straw  by 
the  use  of  powdered  fluor  spar  acting  on  silica  by  the  sulphuric  acid 
present  in  the  soil  and  disengaging  hydrofluoric  gas,  which  corrodes  or 
decomposes  the  silica. 
Anyone  can  try  this  by  treating  powdered  fluor  spar  with  sulphuric 
acid,  and  covering  with  sand  or  powdered  glass.  It  will  give  an  idea  of 
how  fluorine  applied  infinitesimally  in  manures  and  fertilisers  acts  on  the 
silica  of  the  soil,  and  thus  supplies  plants  steadily  with  that  element. 
Make  no  mistake  in  the  matter,  for  fluorine  does  nothing  by  itself,  the 
sulphuric  acid  being  essential  for  the  evolution  of  the  hydrofluoric  acid, 
and  this,  decomposed  by  potassium  and  sodium,  gives  the  fluorides  of 
potash  and  soda,  which  act  promptly  on  eelworms  and  on  fungi.  I  had 
an  idea,  long  ago,  that  these  substances  would  save  Potatoes  from  the 
disease  caused  by  Fhytophthora  infestans,  but  I  did  not  then  know  that 
Fig.  98.— CATTLEYA  MENDELI  OAKES  AMES. 
You  were  gooo  enough  to  allow  me  to  draw  attention,  in  the  Journal 
■of  Horticulture  for  the,  21st  October  last,  to  the  advantages  of  silico-fluoride 
of  ammonium  as  an  insecticide  and  fungicide.  Since  that  date  I  have 
received  letters  upon  the  subject  from  all  parts  of  the  world.  The 
substance  is  extensively  used  in  the  United  States  of  America,  and 
appear.-^  to  have  attracted  the  attention  of  the  Department  of  Agriculture 
some  time  ago,  so  that  our  transatlantic  friends  are  ahead  of  us  in  this 
respect,  as  in  some  others. 
The  following  method  of  making  the  substance  is  simple,  and  all  the 
ingredients  are  perfectly  harmless.  Obtain  1  lb.  of  the  strongest  hydro- 
fluosilicic  acid  ;  it  ought  to  fume  in  the  air,  but  it  does  not  attack  glass 
bottles  or  corks.  Dissolve  this  in  a  quart  of  rain  water.  Then  dissolve  a 
quarter  ot  a  pound 
of  the  strongest 
ammonia  (liquor 
ammoniac  fortiss. ; 
880  is  the  trade 
name  of  it)  in  a 
quart  of  rain  water. 
These  ingredients 
will  cost  about  Is. 
perlb.and  6d.perlb. 
respectively.  Mix 
the  two  fluids,  and 
allow  the  excess  of 
silica,  which  is 
always  present  in 
the  acid,  to  settle 
down.  The  clear 
liquid  will  be  a  toler¬ 
ably  strong  solution 
■of  the  silico-fluoride 
which  must  be 
greatly  diluted  with 
rain  water  before 
applying  to  plants. 
Microscopic  in¬ 
vestigation  has 
shown  that  it  at¬ 
tacks  and  destroys 
•eelworms,  towards 
which  it  behaves 
(like  a  nitrifying 
micro  -  organism. 
This  action  is  very 
probably  due  to 
the  presence  in  the 
eelworm  uf  some 
alkaline  base  for 
which  the  silico- 
fluoridehas  astrong 
affinity.  I  gave  my 
address  in  my  pre¬ 
vious  communica¬ 
tion  ;  cheques  for 
£50,000  can  always 
be  sent  there.  See 
page  571,  December 
16th,  1897.— W.  M. 
[No  doubt  they 
can,  and  perhaps 
our  correspondent, 
after  reading  the 
•following  observa¬ 
tions  and  record  of 
experiments  with 
silico-fluorides,  may 
think  Mr.  Abbey 
entitled  to  a  share 
in  the  spoil.] 
