352 
ACTION  OP  SUNLIGHT  ON  SULPHUROUS  ACID. 
which  abound  upon  the  physical  lecture  table,  I  do  not  know 
whether  the  devices  suggested  in  this  note  have  been  tried  or 
proposed  for  small  chemical  operations  by  any  one  else.*  I  have 
recommended  them  to  students,  and  we  have  found  them  satis 
factory  for  various  analytical,  experimental,  and  pharmaceutical 
operations.  We  have  employed  them  chiefly  in  such  evapora- 
tions as  are  performed  for  the  residue  only,  or,  at  least,  not  for 
quantitative  recovery  of  the  distillate,  in  various  evaporations  of 
quantitative  analysis,  in  the  elimination  of  non-volatile  alkaloids, 
in  determining  the  organic  matter  in  water,  and  in  preparing 
fluid  extracts.  To  evaporate  at  ordinary  temperatures  by  hand- 
pump  exhaustion  is  especially  irksome  in  those  cases  when  appli- 
cation of  125°  to  150°  F.  is  objectionable.  And  to  connect  a 
vessel  under  which  heat  may  be  applied  with  the  air-pump  in- 
volves quite  as  much  labor  as  the  arrangement  of  apparatus  for 
exhaustion  by  condensation.  American  Supplement  to  Chem. 
News  J  New  York,  Jan.,  1870. 
ON  THE  ACTION  OF  SUNLIGHT  ON  SULPHUROUS  ACID. 
By  0.  LoEw, 
Assistant  in  the  College  of  the  City  of  New  York. 
(Read  before  the  "  Lyceum  of  Natural  Science,"  New  York.) 
We  know  that  plants  under  the  influence  of  the  sunlight  re- 
duce carbonic  acid  and  water  to  organic  compounds,  and  organ- 
ized parts  ;  w^e  know  further,  that  the  albuminous  principles,  as 
well  as  some  ethereal  vegetable  oils,  contain  sulphur  which 
doubtless  comes  from  the  sulphates  contained  in  the  soil.  As 
regards  this  reduction  of  sulphuric  acid,  it  seemed  to  me  of 
interest  to  ascertain  whether  sunlight  possesses  any  reducing 
power  upon  the  oxygen  compounds  of  sulphur  out  of  the 
tissues  of  the  plant.  For  this  purpose  I  exposed  diluted  sul- 
phuric acid,  solutions  of  sulphates  and  sulphites  and  aqueous 
sulphurous  acid  under  various  conditions,  in  sealed  tubes  to  the 
sunlight  during  the  last  summer. 
^  This  method  of  producing  a  partial  vacuum  was  employed  by  Barry 
(See  U.  S.  Dispensatory — Evaporation  of  Extracts)  more  than  forty  years 
ago  in  making  extracts  and  volatile  oils. — Editor  Amer.  Jour.  Pharm. 
