164 The Advance of Science. 
difference in sp. gr., mix with it for many days, but lies on the top 
sometimes for a depth of 3 or 4 inches. This has been observed 
by the men who go down the shaft, and no doubt it is the case 
wherever there is very strong brine. Thus it is that the rock salt 
in the lower part of Cheshire is only very, very slightly, if at all, 
becoming dissolved. That it is dissolving in the higher parts is 
inferred from the fact that the land, at long distances from the 
middle of the county where all the salt-works are situated, and at 
a higher level than the works, is steadily sinking in. Thus it 
seems that the sinking of Cheshire is due to two causes—in the 
higher parts to the dissolving of the rock salt and in the lower 
parts to the falling in of the old mines. 
Now, the fact that the salt in the middle of Cheshire is not 
dissolving is a matter of great importance to the brine workers, for 
the inhabitants of that part are trying to get compensation out of 
the owners of the brine works, because, they say, this pumping up 
of the natural brine is causing the land to fall in. But this is not 
the case, for it is found that the land only sinks at that part, if 
there happen to be an old mine underneath, and that where there 
are brine works, and no old mines, no sinking occurs. It has 
been noticed that six months after a very dry season the supply of 
brine becomes lower in the shafts. This seems to indicate that 
the fallen rain takes that time to run its course before it appears as 
brine. 
At most places in England where salt exists at all there are 
both rock salt mines and also brine works, but at Droitwich, in 
Worcestershire, there are two brine works and no mines. In 
Middlesburgh, Yorkshire, rock salt was found, in 1858, 1200 ft. 
below the surface. It was untouched till 1872. Then the great 
iron master, Sir Lowthian Bell, let fresh water down on it, and 
pumped it up again as brine. His great idea was to boil this 
brine by means of the waste heat from the iron-furnaces, and this 
has now been carried into practice. ‘There are many large salt- 
works at Middlesburgh, which are making 200,000 tons per annum 
for the adjacent Newcastle chemical works. 
The Advance of Science. 
S the world grows older, and as the generations pass 
away and their places are taken by the rising genera- 
tion, science progresses; and the mysteries that 
puzzled the alchemists of the middle ages are now 
made clear by new light, shed by the investigations 
made in the general advance of science. 
, 
