ACKROYD : OX THE CIRCULATION' OF SALT. 
405 
The Concentration of Sea-Salt. 
When rain-water reaches the earth its burden of salt necessarily 
becomes concentrated by evaporation. A flat sheet of water will in 
twelve months lower its level 20 inches,^ so that it follows if the 
original depth were 40 inches, the result of a year's evaporation 
would be to double the amount of salt in a given w^eight or volume 
of the residual water ; much quicker must evaporation be from land 
surfaces where capillary action may come into play and constantly 
draw moisture upwards where it is exposed on a maximum of earth- 
surface to the evaporative influence of the sun, or of a higher atmos- 
pheric temperature. 
The final result appears so apparent as to need no proof. I may, 
however, refer to peculiar cases of concentration I have come across 
in the course of this study. Well-waters in the Millstone Grit show 
evidence of concentration in higher chlorine figures, and also that 
the salt is cyclic sea-salt from the fact that it does not increase at the 
same rate as the other solids in solution, whereas, if it were derived 
from the soil, it ought to increase either at the same or at a greater 
rate, because of its greater solubility than that of the other bodies ; 
this is illustrated by the follo-\ving data : — 
Parts per 100,000. 
1 " 
Ratio. 
Total Solids to 
CI. 
Total Solids. 
CI. 
Upland surface water. Average of 
19 Analyses extending over 2^ 
years, Sept., 1898, to Jan., 1901 
Well No. 1 (pure) 
Well No. 2 (pure) 
Well No. 8 (pure) 
1 9-68 
38- 
28- 
38- 
1- 33 
3-85 
2- 00 
2-15 
1 100 : 13-7 
100 : 101 
100 : 71 
100 : 5-7 
The Caspian and Dead Seas. 
This concentration of chlorides is an important geological 
factor. To return to our Pennine reservoir. If there were no out- 
* A four years' mean evaporation from the Torquay watershed, as kindly 
supplied to me by Mr. W. Ingham, C.E., is 20*88 in., 1897-1900. 
