Sulphuric  Acid , in  the  Rain-Water  collected  at  Rothamsted.  319 
Table  II. — The  Average  Amount  of  Nitrogen  as  Ammonia  in  Daily 
Rainfalls  of  different  Quantity,  from  June  22, 1881,  to  January  5, 
1882. 
Number 
of 
Examples. 
Average 
Quantity 
Nitrogen  as  Ammonia,  per  million. 
of  each 
Rainfall. 
Average. 
Highest. 
Lowest. 
Below  '01  inch 
35 
Inches. 
0 006 
1-536 
| 
5-491 
0115 
From  '01  to 
02  inch  . . 
27 
0-014 
1-141 
4-255 
0-247 
From  -02  to 
04  inch  . . 
19 
0-028 
0-924 
2-368 
0-247 
From  "04  to 
06  inch  . . 
5 
0-045 
0-571 
1-235 
0-362 
From  • 06  to 
08  inch  . . 
8 
0-065 
0-359 
0-577 
0-272 
From  '08  to 
10  inch  . . 
6 
0-091 
0-338 
0-576 
0-247 
From  • 10  to 
20  inch  . . 
18 
0-151 
0-232 
0-494 
o-ioo 
From  '20  to 
30  inch  . . 
11 
0-266 
0-360 
1-400 
0-117 
From  '30  to 
40  inch  .. 
7 
0-325 
0-229 
0-700 
0-099 
From  ’40  to 
70  inch  .. 
9 
0-542 
0-138 
0-244 
0-070 
From  "70  to  1 
00  inch  .. 
5 
0-825 
0 138 
0-312 
0-043 
Above  1 • 00  inch 
2 
1-126 
0-063 
0-070 
0-058 
152 
0-142 
0-248 
5-491 
0-043 
a similar  manner,  unless  the  contrary  is  stated.  It  will  be 
noticed  that  several  small  deposits  were  left  unanalysed  during 
the  earlier  part  of  the  investigation.  If  we  assume  for  these 
the  composition  proper  to  their  quantity  and  season,  the  average 
composition  of  the  whole  rainfall  from  June  22  to  January  5, 
amounting  to  21 '645  inches,  becomes  0’254  of  nitrogen  as 
ammonia  per  million  of  water. 
2.  Ammonia  in  Monthly  Rainfalls. — A mixed  sample,  repre- 
senting the  rainfall  of  each  month,  has  been  regularly  prepared 
by  placing  in  a carboy  a fixed  proportion  (1  gallon  for  every 
inch)  of  the  rainfall  of  each  day.  In  June  1881  determinations 
•of  ammonia  were  commenced  in  these  monthly  mixtures,  and 
have  now  been  continued  for  rather  more  than  two  years,  each 
mixture  being  analysed  as  soon  as  possible  after  the  termination 
of  the  month  of  collection.  A considerable  number  of  monthly 
mixtures  of  rain-water,  made  previously  to  June  1881,  were  also 
analysed  in  this  month ; these  samples  were  in  many  cases  of 
considerable  age  when  analysed.  All  the  analyses  of  monthly 
mixtures  will  be  found  in  Table  III.  (p.  321)  ; the  results 
relating  to  old  samples  are  separated  by  a thick  black  line 
from  those  obtained  by  the  analysis  of  fresh  samples. 
It  is  clear  that  the  determinations  in  the  monthly  mixtures 
can  only  be  of  value  if  the  ammonia  originally  in  the  rain 
remains  unaltered  till  the  analysis  of  the  mixture  can  be  made. 
In  our  former  Report  it  was  assumed  that  the  ammonia  in  rain- 
water would  diminish  on  keeping,  that  it  would,  in  fact,  pro- 
