394 
VARIETIES. 
On  the  absorption  and  assimilation  of  carbonic  acids  by  plants. — Mr. 
Boussingault  has  recently  made  some  experiments  on  the  absorption  and 
assimilation  of  carbonic  acid  by  leaves  exposed  to  sunlight.  His  results 
are  thus  summed  up  :  1.  Leaves  exposed  to  the  sun  in  pure  carbonic  acid 
do  not  decompose  this  gas,  or  if  they  do,  it  is  with  excessive  slowness. 
2.  Leaves  exposed  in  a  mixture  of  carbonic  acid  and  atmospheric  air 
rapidly  decompose  the  former  gas.  Oxygen  does  not  seem  to  interfere  in 
the  phenomenon.  3.  Carbonic  acid  is  rapidly  decomposed  by  leaves  when 
that  gas  is  mixed  with  either  hydrogen  or  nitrogen,  The  author  has 
pointed  out  some  analogies  of  these  phenomena  with  the  slow  combustion 
of  phosphorus  under  certain  circumstances.  Thus  phosphorus  placed  ia 
pure  oxygen  does  not  become  luminous,  and  does  not  burn,  or  if  it  does, 
burns  with  excessive  slowness.  In  a  mixture  of  oxygen  and  atmospheric 
air,  however,  phosphorus  burns  rapidly;  it  also  burns  when  placed  in 
oxygen  mixed  with  hydrogen,  nitrogen,  or  carbonic  acid.  Phosphorus, 
which  does  not  burn  in  pure  oxygen  at  an  ordinary  pressure,  becomes  com- 
bustible when  the  gas  is  rarefied  ;  and  Mr.  Boussingault  found  that,  simi- 
larly, a  leaf  placed  in  rarefied  pure  carbonic  acid  decomposed  the  gas  and 
evolved  oxygen. — Reader,  May  27,  and  Amer.  Jour,  of  Science  and  Arts, 
July,  1865. 
The  Agassiz  Expedition  to  South  America. — The  expedition  of  Prof.  Agas- 
siz  arrived  safely  at  Rio  de  Janeiro  on  the  22d  of  April.  The  Emperor 
sent  a  boat  alongside  of  the  Colorado  to  take  the  party  on  6hore,  and  in 
the  evening  had  a  long  interview  with  Mr.  Agassiz.  The  Secretary  of  the 
Treasury  of  Brazil  gave  orders  to  have  the  baggage  and  instruments  of  the 
party  passed  unopened  at  the  Custom  House,  and  every  courtesy  wa3  ex- 
tended to  the  members  of  the  expedition  by  the  officials  of  the  Brazilian 
government. — Boston  Transcript,  June  9,  and  Amer.  Jour,  of  Science  and 
Arts,  July  1865. 
New  Oleoresin. — Recently  some  persons  engaged  in  making  turpentine 
in  Plumas  County,  California,  tapped  some  pine  trees  of  a  species  new  to 
them.  The  fluid  flowed  abundantly,  but  it  had  a  peculiar  odor,  and  when 
taken  to  the  turpentine  stills  in  the  neighborhood,  nothing  could  be  done 
with  it.  At  last  it  fell  into  the  hands  of  a  man  who  managed  to  distil  a 
liquid,  which  proved  to  be  a  new  discovery.  Instead  of  the  disagreeable 
odor  of  turpentine  it  has  a  fragrance  like  citron,  and  is  free  from  all  resi- 
nous matter.  Ten  gallons  of  it  weigh  as  much  as  six  and  three-quarter 
gallons  of  pure  water.  It  dissolves  all  the  animal  and  vegetable  oils,  and 
leaves  no  stain  of  its  own,  nor  does  it  affect  any  of  the  colors  used  in  dye- 
ing, and  thus  it  is  an  excellent  substitute  for  benzine,  without  the  odor 
which  makes  the  latter  substance  so  offensive.  It  is  also  much  cheaper 
than  benzine.  The  new  liquid  is  called  "  erasine,"  because  of  its  value  for 
cleansing.    It  evaporates  rapidly  and  burns  well,  but  it  is  more  expensive 
