March  11,  1*97, 
JOURNAL  OF  HORTICULTURE  AND  COTTAGE  GARDENER. 
207 
up  their  sprouts  better  when  plenty  of  room  is  allowed  for  air  and 
Bun  to  act  upon  them.  Strong  plants  at  2  feet  apart  each  way 
become  a  dense  mass  of  foliage,  which  absolutely  shuts  out  the 
sun’s  rays  ;  but  in  poorer  ground  these  distances  would  suffice. 
Last  year  the  plants  languished  for  want  of  root  moisture,  and  did 
not  attain  to  more,  and  in  many  cases  less  than  half  their  usual 
size  ;  but  the  stems,  though  short,  became  thickly  set  with  good 
sprouts,  even  below  the  soil.  There  was  no  rain  to  do  them 
any  appreciable  good  from  the  time  of  planting  until  September, 
and  it  was  surprising  how  well  they  withstood  the  ordeal,  and  the 
excellence  of  the  crop  they  bore  after  that  date.  If  there  were 
benefits  derived  from  indoor  sowing,  it  was  more  conspicuous  last 
summer  than  is  usually  the  case,  but  notwithstanding  the  gain 
thus  secured,  I  shall  not  be  tempted  to  depart  from  my  custom  of 
sowing  outdoors  in  March. — W.  S. 
CHEMISTRY  IN  THE  GARDEN. 
[  ( Continued  from  page  187.) 
The  material  of  which  the  seoimentary  rocks  are  formed,  was 
derived  first  of  all  from  the  primary  rocks.  The  first  named  rocks 
were  formed  under  water,  but  as  time  went  on  some  of  them  were 
upheaved  by  volcanic  action,  and  so  became  dry  land  ;  they  in  their 
turn  supplying  material  for  the  formation  of  other  sedimentary 
rocks.  As  some  are  formed  from  the  primary,  and  others  from  the 
primary  and  sedimentary,  we  should  in  time  have  many  different 
kinds  of  rocks  upon  the  earth.  To  give  our  readers  some  idea  of 
the  vast  changes  the  rocks  have  undergone,  it  is  only  necessary 
to  say,  that  if  all  the  different  kinds  of  rocks,  which  have  been 
formed  at  various  periods  since  the  formation  of  the  earth,  were 
placed  on  the  top  of  each  other,  they  would  reach  a  height  of  thirty 
miles. 
As  there  are  so  many  different  kinds  of  rocks  upon  the  surface 
of  the  earth,  and  as  the  soil  is  formed  by  the  decay  of  these,  it 
naturally  follows  that  soils  will  vary  quite  as  much  as  the  rocks, 
and  to  a  large  extent  the  former  will  have  the  same  characteristic 
properties  as  the  latter. 
The  Fokmation  of  Soils. 
The  various  agents  which  are  at  work,  breaking  and  wearing 
down  the  rocks  into  soil,  are  as  follows  : — Water,  carbonic  acid, 
oxygen,  changes  of  temperature,  plant  and  animal  life. 
Water  is  the  most  active  of  all  the  disintegrating  agents.  It 
attacks  rocks  and  causes  their  decay  in  two  different  ways — first, 
chemically  ;  and  secondly,  physically.  When  considering  the 
origin  of  soils,  we  saw  that  felspar  aod  mica  contained  silicates  of 
alumina,  potash,  soda,  lime,  magnesia,  and  iron.  Water  itself 
possesses  the  power  to  dissolve  out  some  of  these  constituents 
when  it  comes  in  contact  with  the  surface  of  the  rocks.  Rain 
water  as  it  descends  through  the  air  absorbs  oxygen  and  carbonic 
acid  ;  and  water  containing  these  gases  attacks  the  constituents  of 
rocks  more  energetically  than  would  pure  water.  The  carbonic 
acid  unites  with  the  potasb,  soda,  lime,  or  magnesia,  and  forms 
carbonates  of  potash,  soda,  lime,  or  magnesia,  and  these  substances 
being  soluble  in  water  are  dissolved  and  carried  away. 
The  potash,  soda,  lime,  and  magnesia  are  present  in  the 
minerals  felspar  and  mica  in  chemical  combination  with  silica  and 
alumina.  When  carbonic  acid  unites  with  either  of  the  first- 
named  substances,  and  water  dissolves  and  carries  them  away,  the 
silicates  of  alumina  undergo  a  chemical  change.  As  soon  as  the 
potash,  soda,  lime,  or  magnesia  is  taken  away  from  the  lilicate  of 
alumina  water  takes  its  place — i  e.,  unites  with  the  silicate — and  a 
substance  called  hydrated  silicate  of  alumina,  or  pure  clay,  is 
formed.  Pure  clay  (kaolin)  is  the  substance  which  gives  to  horti¬ 
cultural  clays  their  plastic  sticky  character.  In  gardens  stiff 
tenacious  clays  are  sometimes  burnt.  This  is  done  for  the  purpose 
of  driving  off  the  water  from  the  hydrated  silicate  of  alumina  ;  the 
silicate  of  alumina  (ournt  clay)  left,  being  sand-like  in  character, 
makes  the  clayey  soil  to  which  it  is  applied  more  open  and  porous. 
In  the  mineral  a"gite  the  magnesia  is  present  in  combination 
with  silica.  If  the  magnesia  is  dissolved  out  of  the  mineral  only 
silica  (sand)  would  remain.  Hornblende  contains  large  quantities 
of  protoxide  of  iron  (Fe202),  but  the  substance  on  being  exposed 
to  damp  air  is  oxidised — i.e.,  unites  with  oxygen — and  becomes  the 
peroxide  of  iron,  or  iron  rust  (F<-203). 
This  altering  of  the  chemical  composition  of  the  silicates  of 
alumina,  the  silicate  of  magneTa,  and  the  protoxide  of  iron,  causes 
the  surface  of  the  rock  to  become  soft  or  rotten  ;  and  the  loose 
particles  may  either  remain  to  form  a  film  of  soil,  which  will  be 
increased  in  depth  as  time  goes  on,  or  they  may  be  washed  into  the 
ocean  to  form  sedimentary  rocks. 
Owing  to  the  action  of  wafer,  carbonic  acid,  and  oxygen  the 
surface  of  the  rock  becomes  full  of  tiny  holes.  When  rain  falls 
these  will  fill  with  water,  and  if  a  frost  follows  the  expansion  which 
takes  place  when  water  is  converted  into  ice  causes  small  pieces  of 
rock  to  be  broken  off  from  the  mass.  There  are  very  few  rocks 
which  do  not  possess  fissures  or  cracks  in  them  ;  if  these  during 
wet  weather  get  filled  with  water  and  it  freezes,  huge  pieces  of 
rock  may  be  separated  from  its  parent.  It  is  owing  to  this  cause 
that  so  much  rock  debris  is  found  lying  at  the  bottom  of  cliffs. 
The  disintegrating  agents  will  attack  the  broken  pieces  of  rock, 
and  gradually  convert  them  into  soil.  The  action  of  frost  in 
pulverising  pieces  of  rock  is  well  illustrated  when  pieces  of  chalk 
or  marl  are  put  on  land  in  the  autumn.  During  rainfall  the  pieces 
of  chalk  or  marl  get  saturated  with  water,  and  if  a  frost  follows 
the  expansion  of  the  water  as  it  is  converted  into  ice  (9  cubic 
inches  of  water  become  10  cubic  inches  of  ice)  forces  the  particles 
of  rock  apart,  and  the  lumps  fall  down  into  a  powder  as  soon  as 
they  thaw. 
In  past  ages  the  action  of  moving  ice  (glaciers)  in  grinding 
down  the  surface  of  rocks  into  soil  was  considerable,  thousands  of 
acres  called  drift  being  formed  in  England  by  this  cause. 
There  is  always  a  tendency  in  running  water  to  wash  the  soil 
from  the  hills  into  the  valleys,  and  during  heavy  rainfalls  a  con¬ 
siderable  quantity  of  soil  is  carried  into  the  ocean.  It  has  been 
estimated  that  1  foot  of  the  whole  exposed  surface  of  the  earth  is 
carried  into  the  ocean  every  thousand  years.  To  illustrate  this 
fact,  we  may  say  that  Professor  Geikie  has  found  that  the  Thames 
carries  1,865,903  cubic  feet  of  sediment  (soil)  into  the  North  Sea 
every  year.  The  Thames  is  but  a  small  river  compared  with  the 
Mississippi  and  the  Amazon,  for  it  bas  been  estimated  that  theee 
two  rivers  carry  annually  about  1343  million  tons  of  sediment  into 
the  ocean. 
The  alternating  expansion  by  heat  and  contraction  by  cold  to 
which  the  surface  of  rocks  are  exposed,  cause  the  constituent 
particles  to  become  loosened,  and  they  ultimately  break  down  and 
form  soil. 
Lichens  and  Mosses  grow,  in  the  film  of  soil  formed  on  the 
surface  of  rocks.  When  they  die  they  add  to  this  film  of  soil  a 
certain  amount  of  organic  matter,  and  this  substance,  as  it  decom¬ 
poses,  yields  carbonic  and  other  acids  which  attack  the  constituents 
of  the  underlying  rock,  causing  its  decay,  and  thereby  deepening 
the  soil.  As  time  goes  on  there  would  be  sufficient  soil  formed 
to  support  weeds  and  grasses,  and  the  growth  and  decay  of  these 
plants  would  soon  deepen  the  soil  considerably. 
Earthworms  are  very  active  agents  in  the  formation  of  soils. 
They  swallow  the  earth  for  nourishment,  the  swallowed  earth  being 
afterwards  brought  to  the  surface,  and  forms  the  wormcasts.  They 
draw  into  their  holes  dead  leaves,  which  they  swallow  and  after¬ 
wards  excrete  in  a  partly  digested  form.  Their  burrows  penetrate 
into  the  soil  sometimes  to  a  considerable  depth,  and  these  facilitate 
drainage,  besides  allowing  the  air  to  penetrate  into  it. — W.  Dyke. 
(To  be  continued.) 
COOKING  POTATOES. 
I  should  like  to  say  a  word  or  two  on  this  subject  before  it  is 
dropped.  I  consider  it  a  matter  of  great  importance,  for  it  is  undoubted 
that  only  a  small  proportion  of  the  cottagers  wtn>  can  grow  good  Potatoes 
ever  get  them  really  well  cooked  ;  and  it  is  probable  that  not  only  no 
vegetable,  but  few  articles  of  food,  show  so  much  difference  in  value  and 
wholesomeness  as  badly  cooked  and  well  cooked  Potatoes. 
No,  I  have  got  no  receipt  to  put  forward,  and  I  do  not  at  all  suppose 
I  should  be  able  to  do  it  myself,  though  I  remember  gratefully  the 
napkin  and  wooden  bowl  of  my  childhood  (mentioned  by  a  correspon¬ 
dent)  as  bringing  before  my  m’nd  Potatoes  that  were  truly  p  easant  to 
the  eyes  and  good  for  food  ;  but  I  think  that  those  who  do  know  should 
use  every  post-able  means  of  bringing  before  cottagers  “  how  to  do  it  ” 
and  “  how  not  to  do  it,”  for  I  am  not  at  all  sure  that  it  is  not  more 
important  even  than  the  ocmbating  of  the  Potato  disease  itself. 
The  simplest  possible  way  is  a  class  for  boile-l  Po'atces  at.  cottagers’ 
shows,  at  which,  of  course,  punctuality  in  bringing  and  judging  at  an 
appointed  time  must  be  strictly  adhered  to. 
In  my  own  village  I  quite  think  that  this  class  has  done  a  great  deal 
of  good.  The  first  time  it  was  instituted  at  our  cottage  show  the  exhibits 
showed  the  need  of  it  as  plainly  as  possible — one  dish  was  a  picture,  and 
easily  gained  first  prize.  Of  course  they  were  tested  and  tasted.  And 
two  or  three  of  the  others  apparently  contained  shapeless  pieces  of 
yellow  soap,  as  unappetising  and  unwholesome  as  possible.  The  next 
year  the  first  prizewinner  held  her  own,  but  there  were  good  second  and 
third,  and  no  very  bad  ones.  And  in  the  third  year,  or  once  or  twice 
since,  she  has  been  beaten  ;  and  last  year  I  could  have  eaten  the  lot, 
and  as  the  bardworked  Secretary,  and  everything  else,  having  missed 
my  luncheon,  felt  quite  capable  of  it. 
How  plain  it  was  that,  by  teaching  the  wives  in  this  practical  way, 
we  bad  helped  the  cottagers  themselves  to  a  far  greater  enjoyment  of 
those  Potatoes  which  they  grew  so  well,  and  gained  prizes  for  in  their 
raw  state  in  the  other  classes. 
Secretaries  and  committees  of  cottagers’  shows,  please  note.— 
W.  E.  Rullem. 
