404 
ACKKOYD : ON THE riRCULATION OF SALT. 
The following is a synopsis of results up to date, the chlorides in 
the rainfall being calculated into annual downfall of salt per unit area : — 
l>]ace. 
Distance 
from 
the Sea. 
Deposit of NaCl per 
acre per year. 
observers. 
Cirencester . . . 
35 miles 
36 lbs. (average of 26 
Church, Prevost, and 
years) 
Kinch* 
Rothamsted ... 
24*59 lbs. (average 6 
Lawes, (Jilbert, and 
years) 
Warrington t 
Perugia 
7'") miles 
37-8 lbs 
Belluccit 
(ieorge Town, 
186 lbs 
Harrison t 
Demerara 
Widdop 
40 miles 
172 lbs 
Ackroyd 
As to the particular nature of this salt circulation, we may suppose 
(1) that salt spray from the sea is carried to the land to distances 
varying with the force of the wind ; (2) that when the salt is dried 
by evaporation it is carried further inland with the dust ; and (3) 
that rains dissolve it and bring it down to the rivers by which it is 
carried back to the sea. 
Of the carrying of the salt spray, abundant evidence, as I have 
shown, has been obtained in times of storm, and of the presence 
of sodium in dust at all times the spectroscope yields never-failing 
proof, while in the examination of rain-water I have found the 
highest chlorine contents in light I'ainfalls. 
The full extent inland of salt circulation has yet to be determined. 
It may not be entirely limited by mountain chains barring the direction 
of prevalent sea-winds, as finely-divided sea spray may possibly be 
carried nearly as far as the dust of Krakatoa. This much, however, 
we know, that the farther one gets inland and the less the chlorine 
figure becomes for rain-water. Angus Smith has published some 
averages for rain| in terms of hydrochloric acid per million. I have 
converted his figures to parts of chlorine per 100,000 of rain-water, 
and arranged them as follows in proof of this diminishing distribution : 
Ireland, Valentia 4-72 
Liverpool .'V49 
English Towns 0-84 
Darmstadt .. .. ^. 0-09 4 
Trans. Chem. Soc., Vol. 77, p. 1273. I Ibid. 
t Air and Rain, Longmans, London, 1872, p. 281. 
