280 
THE  TROPICAL  AGRICULTURIST. 
fOcT.  I,  i8g6. 
method  is  that  the  size  of  the  fragmeut  does  not  affect 
the  result ; a miuute  fragment  only  just  large  enough 
to  be  visible  is  equally  couveuiaut ; in  f ict  is  more 
convenient  than  a larger  one. 
If  a stone  in  the  rou^h  is  under  examination, 
a mine  chip  can  easily  be  taken  from  it,  and 
Used  for  the  experiment  in  the  most  satis- 
factory manner.  The  method  is  moreover  extremely 
sensitive;  a mere  drop  of  benzene  added  to  a con- 
siderable volume  of  the  liquid  is  sufficient  to  send  to 
the  bottom  a stone  which  was  previousl}'  floating. 
So  much  for  stones  whose  density  is  less  than  that 
of  chrysolite.  As  regards  the  denser  minerals,  it  was 
Until  a short  time  back  impossible  to  test  them  by 
any  such  method  they  all  sank  in  the  heaviest 
liquid  available.  But  now,  thanks  to  the  fortunate 
discovery  by  Ur.  Retgers  of  the  remarkable  properties 
of  thallium-silver  nitrate,  all  the  known  gem  stones 
may  be  distinguished  by  a similar  process. 
This  salt,  which  may  be  prepared  by  fusing 
together  in  equal  molecular  proportions  nitrate 
of  silver  and  nitrate  of  thallium,  possess  the 
remarkable  propertj'  of  fusing  at  a temperature 
far  below  that  of  either  of  its  constituents,  and 
well  below  that  of  boiling  water,  while  at  the 
same  time  the  fused  salt  possesses  a speciflo  gravity 
greater  than  that  ^of  zircon.  The  salt  fuses  at  75°  C. 
to  a clear  colourless  liquid  in  which  zircon  just 
floats ; it  further  possesses  the  useful  property  of 
being  miscible  in  all  proportions  with  water,  so  that 
the  specific  gravity  cau  be  reduced  to  any  desired 
extent  by  adding  water,  just  as  that  of  methyleuo 
iodide  was  reduced  by  adding  benzene.  The  sub- 
stance can  be  kept  liquid  by  maintaining  it  at  a 
temperature  above  75°  C.,  and  this  may  easily  be 
done  by  immersing  the  vessel  in  which  it  is  obtained 
in  water  heated  to  near  the  boiling  point. 
In  these  two  liquids  then  we  have  the  means  of 
producing  a liquid  of  any  required  density  for  the 
discrimination  of  gem  stones,  since  we  can  obtain 
from  one  or  the  other  a liquid  in  which  any  precious 
stone  will  be  exactly  suspended. 
The  nitrate  might  be,  used  by  itself  to  include 
the  whole  series,  but  it  is  more  convenient  to  use 
the  methylene  iodide  when  possible,  both  be- 
cause it  can  be  employed  at  ordinary  tempe- 
ratures and  because  it  is  cheaper  than  the 
nitrate. 
Both  substances  darken  on  exposure  to  light, 
and  shoidd  be  both  kept  and  used  in  the  dark  as 
far  as  possible;  they  are  easily  freo Hroin  the  liquid 
employed  to  dilute  them.  The  benzene  readily 
evaporates  spontaneously  from  the  methylene  iodide, 
and  the  water  cau  be  driven  off  from  the  diluted 
thallium-silver  nitrate  by  boiling. — Journal  of  the 
/Society  of  Arts,  Aug.  11. 
THE  BANANA  TBADE  OF  FIJI. 
In  a recent  article  we  suggested  tiiat  the 
future  export  of  fruit  from  tiii-s  colony  would 
require  to  be  conducted  on  ever  improving  con- 
ditions if  the  hold  we  at  present  [losscss  in  tlie 
Colonial  markets  is  to  be  maintained.  We  also 
indicated  the  nature  of  the  competition  we  had 
to  encounter  by  reason  of  the  superior  facilities 
that  were  being  offered  by  the  Colonial  govern- 
ments with  the  intention  of  encouraging  grow- 
' crs  to  build  up  a permanent  fruit  imlustry. 
It  would  be  well,  that,  that  tiie  [leople  of  this 
colony — no  less  the  commercially  interested 
than  the  actual  producer,  for  the  whole 
fruit  industry  is  inexcricably  associated  re- 
the  one  interest  with  the  other — let  no  opportu- 
nity escape  them  to  keep  abreast  with  their 
neiglibours,  in  assisting  the  producers  in  every 
way  |>ossible,  by  facilitating  despatcli  and  by 
all  other  conceivalile  means.  Our  largest  export 
of  bananas  in  any  one  single  year  was  ecpial 
to  X0:i,l)29  biimdies  in  1.S92,  and  since  that  year 
the  decline  in  shipments  Ini-s  been  very  marked, 
s^iecially  to  Australia.  No  doubt  the  circum- 
scribed purchasing  power  of  those  colonies,  con 
sequent  upon  the  evils  left  in  Uie  trial  of  the 
Banking  Crisis,  had  much  to  do  with  the  de- 
cline, but  was  not  wholly  responsible  for 
it.  We  have  to  look  nearer  home 
for  the  causes  wliich  led  to  the  great 
duction  of  the  output,  and  opened  the  door, 
s)  to  .speak,  for  our  neighbours  t o avail  tliem- 
s.dveso!  our  neglected  opportunities.  Meaniimo 
Queensland,  New  Hebrides,  Kirotouga,  Norfolk 
Island,  and  the  Friendly  Islands  have  stopped 
into  the  breach,  which  we  through  our  clunisi- 
ne.ss  so  obligingly  left  open,  with  the  result  that, 
now  the  colony  is  inclined  to  re-enter  the  arena 
witli  new  vigor,  it  has  a strong  competition  to 
encounter.  Notwithstanding  this,  however,  with 
the  excellent  quality  of  our  fruit,  for  which  it 
is  famed,  with  fast  and  direct  communication, 
and  with  the  experience  which  we  have  gained  in 
the  hard  school  of  adversity,  the  probability 
is  that  we  shall  regain  our  former  jiosition  in 
the  trade  ; while  the  addition  competition,  gene- 
rally spoken  of  as  the  soul  of  business,  whicli  we 
have  now  to  face,  shouhl  lend  a zest  to  the  cam- 
paign to  which  before  we  were  strangers.  It  is 
needless  to  recount  all  our  previoii-;  shortcomings 
in  connection  with  this  trade;  sufficient  tc  say 
they  were  many  anil  varied.  Tne  principal  of 
the.se  however  were  over-shipment,  non-grading, 
neglect  of  seasons,  rough  handling,  and  the 
practice  of  shi|)pers  breaking  np  their  shipments 
into  various  eonsigmnents,  and  so  permitting  the 
fruit  grown  on  one  plantation  to  enter  into  com- 
petition when  it  reached  the  o|)eu  market, 
the  one  consignment  with  the  other 
in  tlie  same  city.  All  these  mis- 
takes of  former  years  will  require  to  be  care- 
fully guarded  agauist  or,  at  any  rate,  mitigated 
as  much  as  foresight  can  suggest.  Uf  times  of 
old  when  fruit  has  been  rushed  into,  say,  the 
Sydney  market,  if  such  an  act  of  vandalism 
could  li.ave  been  justified,  it  would  have  been 
largely  to  the  advantage  of  shippers  if  half  the 
fruit  bad  been  thrown  overboard,  and  by  this 
rough  mode  a glutteil  market  would  have  been 
avoided.  I’roducers  will  have  to  guard  as  much 
as  ]iossible  that  the  miu  kel.s  are  not  flooded  with 
fruit.  The  difficulty  is  not  easy  of  solution, 
but  from  jiasL  experience  we  are  aware  that  it 
would  be  ]>referable  that  the  fruit  should  lie 
jierniitted  to  rot  on  the  idantation  rather 
than  that  it  should  go  forward  to  a mar- 
ket that  is  over-supplied.  Manufactures,  of  course, 
have  a large  advantage  over  fiuic  producers,  but 
they  are  ever  on  the  watch  to  prevent  their  goods 
flooding  a market— and  the  output  of  their  wares  is 
restricted  accordingly.  Nevertheless  the  same  laiv, 
that  of  supply  and  demand,  governs  the  sale  of 
both  produce  and  manufacture.  The  difliculty  to  be 
coped  with,  would  be  very  much  minimised  were 
cable  communication  practicable,  so  as  to 
admit  of  the  early  receipt  of  the  state  of 
the  various  markets.  Possibly  the  proposed 
Pacific  cable  will  be  completed  and  at 
our  disposal  by  the  end  of  1898  ; meantime  it  is 
imperative  that  reliable  information  as  to  the 
requirements  of  the  market  should  reach  the 
colony  at  the  earliest  po.ssible  moment.  How  this 
is  to  be  obtained  is  a matter  for  consideration. 
To  be  effectual,  the  information  requires  not  only 
despatch  but  it  must  be  unimpeachable,  and 
to  secure  this,  it  would  appear  to  be  necessary 
that  the  services  of  smart  business  men  be 
retained  on  behalf  of  the  colony  at  the 
three  centres  of  iSydney,  Auckland,  and 
Melbourne.  And  if  it  then  be  deemed  nece.s.sary 
in  the  interest  of  the  industry  to  secure 
tlic  aid  of  these  gcatlemeii,  theiv  services 
^ -9 
