276 
Tnfluence  of  Electric  Light. 
f  Am.  Jour.  Pharm.. 
1      May,  1883. 
cent.).  Bromine  and  osmic  acid  are  too  expensive.  Corrosive  sublimate  is 
very  poisonons  ;  its  action,  however,  is  so  very  quick  that  it  could  be  used 
for  solid  substances,  which  could  then  be  washed  well  with  water. 
Substances  effective  in  checking  the  germination  of  spores  are  corrosive- 
sublimate,  some  essential  oils,  thymol,  and  amyl  alcohol. — Jour.  Chem.  Soe.,, 
1883,  249.    Chem.  Centr.,  1882,  509,  512. 
INFLUENCE  OF  THE  ELECTRIC  LIGHT  ON  THE 
DEVELOPMENT  OF  PLANTS. 
By  p.  p.  Deherain. 
The  author's  experiments  were  made  at  the  Palais  d'Industrie  during  the- 
Electric  Exhibition  of  August,  1881.  A  greenhouse  was  constructed  and 
divided  into  two  compartments,  one  of  which  was  glazed  with  blackened  per- 
fectly opaque  glass,  whilst  the  other  was  exposed  to  the  ordinary  diflused 
daylight  of  the  Exhibition  building.  The  darkened  chamber  was  illu- 
minated continuously,  night  and  day,  by  a  2000-candle  arc-light  from  a 
Gramme  machine,  driven  by  an  Otto  gas-engine.  The  transparent  chamber 
was  illuminated  at  night  only  by  the  electric  light.  Five  series  of  compara- 
tive observations  were  made,  viz. : — 
1.  Plants  exposed  night  and  day  to  the  electric  light  alone. 
2.  Plants  exposed  during  the  day  to  the  diffuse  daylight  of  the  Palais,  and 
during  the  night  to  the  electric  light. 
3.  Plants  living  during  the  day  in  the  open  air,  and'receiving  the  electric 
illumination  at  night. 
4.  Plants  passing  the  day  in  the  diffuse  daylight  of  the  Palais,  and  the 
night  in  darkness. 
5.  Plants  living  normally  in  a  garden. 
The  plants  submitted  to  experiment  were  barley,  flax,  beans,  and  a  num- 
ber of  garden  and  greenhouse  plants. 
Action  of  the  Unprotected  Light. — At  the  end  of  seven  days  the  naked 
electric  light  was  seen  to  have  an  injurious  effect  both  on  those  plants  which 
were  constantly  subjected  to  it,  and  in  a  less  degree  on  those  which  were 
exposed  to  it  during  the  night  only.  The  leaves  blackened,  withered,  and 
dropped  off;  the  injury  was  confined  to  the  epidermal  layers,  and  was  due 
to  the  direct  impact  of  the  luminous  radiations  (and  not  to  the  formation  of 
nitrogen  oxides ; ;  for  where  one  leaf  was  partly  shaded  by  another,  a  sharp 
line  was  photograjDhically  impressed. 
Experiments  on  Eloclea  cauaclensis,  submerged  in  flasks  of  water,  showed 
that  whilst  the  diffuse  daylight  of  the  building  was  unable  to  cause  decom- 
position of  carbonic  anhj^drlde  and  evolution  of  oxygen,  the  direct  rays  of 
the  electric  light  were  able  to  do  so,  about  as  much  oxygen  being  obtained 
during  an  exposure  of  four  or  five  days  and  nights  to  the  electric  light  as 
could  be  obtained  in  an  hour  or  so  in  bright  sunlight.  At  the  end  of  15  days 
the  arc-lights  were  enclosed  in  globes  of  transparent  glass.  Siemens' just 
published  experiments  having  shown  that  the  injurious  action  of  the  direct 
radiations  was  thereby  modified. 
