416 
ACKROYD : ON TlIE CIRCULATION OF SALT. 
observable on well-painted gates and on the upper windows of houses, 
which were rendered quite dim by the incrustation. It was also 
observed to come through the crevices of a barn-door like smoke, 
and the reflection of the light on it caused it to glisten very brilliantly. " 
County of Durham.— Canon Tristram, whose attention I had 
called to this subject, kindly wrote on the 11th of March, 190*2 : — 
" It may interest you to know, with respect to the storm of 6th and 
7th January, 1839, which I well remember, a fact which came 
under my ow^n observation. At the Castle, Castle Eden, which 
stands on a bluff not far from the east coast of the County of 
Durham, and overlooking the sea. on the morning of the 7th 
January all the windows of the Castle facing west were covered with 
<'i. saline incrustation like hour frost, while those on the east face had 
not a trace of salt on them," 
FiKTiiEit Evidkxcj: of Salt Circulation in Calmer 
Tdies. 
It is probable, as I have attempted to show by chemical evidence, 
tliat winds blowing from the sea are always more or less salt-laden. 
Armand (xautier has quite recently made a determination of the 
amount of salt in sea air (Bull. Soc. Chim., 1899 (iii), 21, 391-392). 
A known volume of air at the Rochedouvres Lighthouse was as- 
pirated through a long plug of asbestos wool, which was afterwards 
washed with hot water in which the soluble chlorides were then 
determined. The air was collected both during day and night in 
fine dry weather with a W.N.W. wind blowing from the open sea. 
The aspirator was nine metres (29^ ft.) above the sea-level. For 
a mean temperature of 15° C. the chlorides found worked out to 22 
milligrams per cubic metre of air (equal to 0*259, or say j of a grain 
per cubic yard), which Gautier regards as the maximum quantity 
of salt which air can retain in suspension. 
On the Origin of the Saltness of Salt Lakes. 
These various facts enable one to realise that with extreme 
meteorological conditions, such as liave admittedly obtained in 
the past history of the Jordan watershed, it may have been no 
