ORIGIN OF ROOK-SALT. 16 
So far our experiment has been in favour of the origin of 
rock-salt from sea-water, since we find in salt mines a similar 
arrangement in masses or layers. 
We may carry the argument still further, for not only do we 
find in the rock-salt mines the ingredients of sea-water; but 
what is of importance, the relative proportions of these 
ingredients are nearly similar to those in sea-water. 
Thus, the chloride of sodium is largely in excess of everything 
else, the next in proportion is the sulphate of lime, and the rest 
in much reduced quantities. Out of the hundreds and thousands 
of chemical salts which make up the bulk of inorganic chemistry, 
where we find six of these associated in a state of solution, it is 
very natural to infer, when we meet with the same six forming 
a solid deposit, that the connection is the result of some natural 
law and not one of mere accident, and that our -salt deposits in 
Cheshire are due to the evaporation of sea-water. It was ‘no 
fortuitous concourse of atoms” which had brought these identical 
bodies together under such different circumstances. 
In confirmation of this theory, we can point to an instance 
in which the operations we have indicated have long been in 
existence, and are now well nigh approaching completion. I 
allude to the vast salt deposits in and around the Dead Sea. 
The following details may not be out of place :— 
The great depression in the Jordan Valley is 150 miles in 
length, with a breadth of 12 miles. The lowest point in 
it is occupied by the Dead Sea, some 46 miles long, and an 
average width of 10 miles. On both sides of it there are 
mountain ranges which run parallel with it. The surface of 
the Lake is 1292 feet below the level of the Mediterranean. 
‘Its greatest depth is 1308 feet, giving a total depression below 
the Mediterranean of 2600 feet. The Jordan flows into the 
Lake at the North end. There is no outlet for its water. 
A column of water, 20 feet in depth, is annually evaporated. 
Its specific gravity is 1-228, water being reckoned at 1-000. 
It contains over 26 per cent. of saline matter, which is a trifle 
more than the best brine springs in Cheshire, mainly made up 
