﻿188 
  PHOCEEDINGS 
  OF 
  THE 
  FOtmill 
  ENTOMOLOGICAL 
  MEETING 
  

  

  larvicidal 
  value 
  of 
  the 
  salt 
  would 
  be 
  maintained 
  if 
  it 
  killed 
  the 
  larvae 
  

   before 
  they 
  pupated. 
  With 
  regard 
  to 
  the 
  second 
  point, 
  attempts 
  were 
  

   made 
  to 
  obviate 
  the 
  difficulty 
  in 
  the 
  following 
  ways 
  :— 
  

  

  (1) 
  The 
  salt 
  was 
  administered 
  in 
  exceedingly 
  fine 
  particles 
  by 
  first 
  

  

  subliming 
  it 
  ; 
  but 
  in 
  practice 
  sublimation 
  cannot 
  be 
  recom- 
  

   mended 
  as 
  it 
  has 
  been 
  shown 
  that 
  the 
  salt 
  dissociates 
  in 
  the 
  

   sublimed 
  condition 
  into 
  Hg 
  and 
  HgClg. 
  

  

  (2) 
  The 
  salt 
  might 
  be 
  thoroughly 
  shaken 
  with 
  a 
  highly 
  viscous 
  and 
  

  

  the 
  least 
  possible 
  volatile 
  material 
  of 
  low 
  specific 
  gravity 
  

   (such 
  as 
  the 
  " 
  non-drying 
  " 
  oils), 
  and 
  the 
  mixture 
  poured 
  over 
  

   the 
  water. 
  So 
  far 
  as 
  has 
  been 
  tried, 
  this 
  form 
  of 
  treatment 
  

   merits 
  attention. 
  

   For 
  larvicidal 
  purposes 
  the 
  superiority 
  of 
  HgCl 
  over 
  the 
  other 
  halogen 
  

   salts 
  of 
  mercury 
  lies 
  in 
  its 
  cheapness 
  whereas 
  its 
  advantage 
  over 
  HgCl, 
  

   and 
  Hgia 
  2KI 
  lies 
  not 
  only 
  in 
  its 
  insolubility 
  and 
  harmless 
  effect 
  on 
  

   man, 
  but 
  also 
  in 
  the 
  fact 
  that 
  the 
  two 
  soluble 
  salts 
  are 
  apt 
  to 
  form 
  precipi- 
  

   tates 
  with 
  the 
  alkaloidal 
  and 
  other 
  constituents 
  of 
  various 
  kinds 
  of 
  vege- 
  

   tation 
  likely 
  to 
  occur 
  in 
  the 
  breeding 
  places 
  of 
  mosquitos.* 
  Over 
  

   kerosine 
  its 
  one 
  great 
  advantage 
  is 
  that 
  it 
  is 
  non-flammable. 
  

   The 
  larva? 
  experimented 
  with 
  were 
  those 
  of 
  S. 
  albopicia. 
  f 
  

  

  Explanation 
  of 
  graphs. 
  

  

  Graph 
  1. 
  (Plato 
  XXIX). 
  

   The 
  figures 
  indicate 
  time 
  in 
  hours. 
  

   Crosses 
  indicate 
  when 
  observations 
  were 
  taken. 
  

   Each 
  line 
  represents 
  one 
  full-grown 
  Stecjomyia 
  albopicia 
  larva. 
  

   (X) 
  indicates 
  death 
  point. 
  

  

  The 
  point 
  where 
  the 
  line 
  breaks 
  indicates 
  the 
  time 
  when 
  the 
  larva 
  began 
  to 
  show 
  

   symptoms 
  of 
  sluggishness. 
  

  

  Graph 
  2. 
  (Plate 
  XXIX) 
  

   In 
  all 
  the 
  experiments 
  the 
  water 
  had 
  a 
  constant 
  surface-area 
  of 
  G 
  inches 
  diameter* 
  

   the 
  quantity 
  of 
  HgCl 
  used 
  being 
  0-001 
  gram. 
  

  

  Graph 
  3. 
  (Plate 
  XXIX). 
  

   In 
  all 
  the 
  experiments 
  the 
  water 
  had 
  a 
  constant 
  depth 
  of 
  10 
  mm., 
  the 
  quantity 
  of 
  

   HgCl 
  used 
  being 
  0-001 
  gram. 
  

  

  * 
  The 
  alkaloidal 
  precipitates 
  with 
  HgCl„ 
  have 
  the 
  general 
  composition 
  B. 
  HCI. 
  HgClj 
  ; 
  

   the 
  alkaloidal 
  precipitates 
  with 
  Hgl, 
  2KI 
  (Mayer's 
  Reagent) 
  vary 
  m 
  composition.— 
  

   Henrv. 
  The. 
  plant 
  aUnloids, 
  1913. 
  . 
  , 
  ,. 
  

  

  t 
  "This 
  paper 
  was 
  read 
  before 
  the 
  Sixth 
  Indian 
  Science 
  Congress, 
  certain 
  alterations 
  

   and 
  modifications 
  being 
  subsequently 
  introduced. 
  

  

  