l 60 WlLILAM J. HODGETTS 
and mentions that the underground water of a well gave opposite 
results. 
These conclusions certainly do not apply to Hawkesley Hall 
Pond (which nevertheless receives most if not all of its water from 
surface-drainage of the land), as even a cursor}? examination of the 
curves of Fig. 3 will show; and even in the cases noted where the 
concentration of the water increases simultaneously with a rise of 
the water-level, the explanation put forward by Transeau in the case 
of the American ponds is not adequate to explain the facts in the 
present instance. Of course it must be borne in mind that the 
amount of soluble matter carried into a pond by drainage-water 
depends very largely upon the geological nature of the rock-strata 
in the neighbourhood of the pond; and this fact alone would very 
seriously interfere with the general applicability of the results 
obtained from Transeau's examination of ponds in central Illinois. 
From what has been said already there is reason to believe that 
the water of Hawkesley Hall Pond contains rather large amounts of 
organic matter in the form of soluble peaty compounds resulting from 
the decay of the various phanerogamic and algal species, and a few? 
determinations w^ere carried out to ascertain roughly the proportion 
of these organic substances to the inorganic salts in the water. 
With regard to the hardness of the water of the pond, wdiich 
W'as determined 1 each month from June 1920 onwards, the following 
table gives the results obtained: 
Table showing the Degrees of Hardness 2 of the Water of Hawkesley 
Hall Pond from June 1920 to June 1921. 
1920 1921 
( 
A 
r~ 
M 
rP 
■‘A*—-— 
s 
On 
M 
10 
00 
M 
vO 
M 
fO 
c© 
0* 
vO 
W 
w 
M 
>5 
S 
O 
s 
p 
1—a 
ib 
'p 
1—» 
bb 
p 
< 
-P 
A 
<u 
m 
O 
O 
Nov. 
i 
►—> 
Feb. 
B 
ci 
a 
*C 
A 
< 
1 
O 
fl 
P 
1—5 
Temporary) 
Hardness ) 
3*5 
3‘3 
3-3 
3-8 
3’9 
3*9 
3*8 
3*6 
3*4 
3*5 
3.6 
4-o 
4*5 
Permanent) 
Hardness ) 
o-5 
o-5 
o-5 
o-6 
o*6 
o-6 
o*6 
0*5 
0-5 
0-5 
o-5 
0“6 
0'6 
Total ) 
Hardness ( 
4*0 
3-8 
3.8 
4’4 
4*5 
4*5 
4*4 
4 -i 
3*9 
4*o 
4*i 
4-6 
5‘i 
F rom this table it is obvious that the hardness of the water between 
May 1920 and June 1921 tended to remain remarkably constant, so 
1 By Hehner’s method, as described, for instance, in Newth’s Manual of 
Chemical Analysis, p. 328. 
2 Temporary hardness is due to calcium or magnesium carbonate, per¬ 
manent hardness to (mainly) calcium or magnesium sulphate. A degree of 
hardness is equivalent to 1 part of CaC0 3 in 100,000 parts of water. 
