62 
Proceedings of the Royal Society 
With an alkalinity between 40 and 50 water has a density 
between 1*024 and 1*025 as a general rule, and when the alkalinity 
is over 50 the density is almost invariably over 1*025. 
There are a number of exceptions apparent on looking over these 
tables, and the exceptions are too numerous to be accidental. 
To discuss the bearings of alkalinity on the other properties of 
the water with any degree of satisfaction, it would be necessary to 
translate the number representing alkalinity per litre into that 
representing alkalinity per 100 parts of total salts. If it could be 
correctly assumed that the composition of the total salts is constant, 
like the composition of ocean- water salts, this could easily be done 
by calculation from the density. But it is evident from purely 
ct priori considerations, that such an assumption cannot be made, 
for the composition of the dissolved salts of river water is quite 
different from that of the salts of sea water, and consequently estuary 
water is not a solution of sea-water salts diluted more and more 
with pure water, but a solution of sea- water salts mixed more and 
more largely with a much more dilute solution of salts in a 
different proportion. 
In consequence of inability to compare the alkalinites with the 
total salts, it is impossible to form a correct idea of the difference 
between bottom and surface alkalinities, as this difference may be 
entirely due to the different salinity of the water. 
The following table (XIII.) shows that the difference in alkalinity, 
like that in salinity between surface and bottom water, is greatest at 
the highest point in the river, and decreases rapidly as the sea 
is approached. 
Table XIII. 
Station III . , near Grangemouth. 
Bottom. 
Surface. 
Difference. 
Mean difference. 
44*7 
34*3 
10*4 
47*4 
28*5 
18*9 
14*7 
Station V . , near Inchgarvie. 
56*9 
47*9 
9*0 
51*8 
46*5 
5*3 
45*0 
42*1 
2*9 
53*9 
48*6 
5*3 
5*6 
Station VII., near InchTceith. 
50*4 
48*2 
2*2 
48*6 
48*6 
0*0 
IT 
For particulars as 
to density, &c., 
see Table XII. 
