328  New  Determinations  of  Ammonia,  Chlorine,  and 
In  the  more  rarified  atmosphere  of  summer,  gaseous  diffusion 
will  probably  be  more  active,  while  the  power  of  transporting 
minute  solid  particles  will  be  diminished. 
It  is  difficult  to  ascertain  the  influence  which  the  direction  of 
the  wind  has  had  on  the  composition  of  a monthly  rainfall  ; a 
partial  study  has  been  made  of  the  data  at  our  disposal,  but 
with  no  definite  result. 
The  amount  of  chlorine  annually  contributed  by  the  rain  to 
the  land  at  Rothamsted  has  amounted  to  14-92  lbs.  per  acre  on 
an  average  of  six  years  ; this  amount  is  equal  to  24-59  lbs.  of 
pure  common  salt,  an  amount  of  chlorides  greater  than  that 
which  is  contained  in  most  farm-crops.  It  was  pointed  out  in 
the  previous  Report  that  the  chlorine  determinations  in  the  rain 
agreed  with  those  made  in  the  drainage-waters  from  the  three 
drain-gauges,  containing  unmanured  and  uncropped  soil.  During 
the  six  years  'now  in  question,  the  average  quantity  of  chlo- 
rine annually  found  in  these  drainage-waters  has  amounted  to 
15’30  lbs.  per  acre. 
Tee  Sulphuric  Acid  in  Rain. 
An  attempt  has  been  made  during  the  last  two  years  to  deter- 
mine the  amount  of  sulphuric  acid  contained  in  the  rain  at 
Rothamsted.  The  investigation  has  been  attended  with  several 
difficulties,  and  the  question  cannot  as  yet  be  considered  as 
satisfactorily  answered  ; the  results  are  nevertheless  of  interest. 
As  it  was  feared  that  the  rain  furnished  by  the  large  rain- 
gauge  would  not  be  suitable  for  determinations  of  sulphuric 
acid,  partly  from  the  presence  of  lead  in  the  water,  and  partly 
from  the  possible  oxidation  of  sulphur  in  the  vulcanised 
caoutchouc  tube  conducting  the  rain  to  the  measuring  cylinders, 
an  independent  collection  of  rain  was  made  for  the  purpose  of 
the  present  investigation.  The  new  collector  consisted  simply 
of  a large  glass  funnel,  placed  in  a bottle,  which  was  sunk  up  to 
its  shoulder  in  the  ground  in  the  neighbourhood  of  the  large 
rain-gauge.  The  rain  was  allowed  to  accumulate  in  the  bottle, 
and  was  removed  at  the  end  of  each  month.  The  water  thus 
collected  was  apt  to  contain  insects  in  summer  time. 
At  the  Rothamsted  Laboratory  no  attempt  has  been  made  to 
determine  the  amount  of  sulphuric  acid  present  in  the  rainfall  of 
each  month  ; the  determinations  have  been  made  in  mixed  samples 
of  water  representing  the  rainfall  of  the  six  summer  and  of  the 
six  winter  months.  Approximate  determinations  of  sulphuric 
acid  in  forty  monthly  mixtures  of  rain-water  collected  in  the 
large  gauge  at  Rothamsted  have,  however,  been  made  by  Dr.  W. 
J.  Russell,  who  is  at  present  investigating  the  chemistry  of  rain. 
