BRINE-SPRINGS AND SALIFEROUS MARLS. 253 
In dry seasons their water fails, and at this very time (September 
1883) only a partial supply is obtainable. The brine-springs remain 
as strong as ever. ‘This fact, together with the force noted in the 
brine-springs, affords strong evidence that the water-systems are 
separate. I believe the brine-springs are derived from the Bunter 
Sandstones of the Lickey Hills, where the immense supply of pure 
water is obtained for Birmingham, and where the river Salwarpe, 
flowing through Stoke and Droitwich, rises. The great difference in 
elevation at once gives us ap explanation of the force which per- 
meates the rock-salts intervening, and supplies the brine-springs of 
such remarkable force. 
Turning to the chemical composition of the brine, the extraordinary 
strength of it is at once noticeable. Taking the solid constituents 
contained in 10,000 parts of sea-water, we find :— 
Miediterraneam). 2.6 2) .ucw Sane 410 grains. 
Hnedishi Channel 2g eas sci ee ame aoOns we 
GoeumanmyOeeam p00 .)2 we sinks ede BAS Aen. 
aC heed Merete, ste ids tie whe ain eh AOS 
The Dead Sea 24°6 per cent. solid matter*. 
Droitwich brine, 38-40 per cent. at Droitwich and Stoke re- 
spectively. 
As 42 is the absolute saturation-point of common salt, the strength 
of the brine isapparent. Mr.Corbett further informs me that he has 
known the Stoke brine to be of such strength that salt would not 
dissolve in it, a proof of the brine being absolutely saturated. 
At Droitwich the strength of the brine varies slightly. If the 
springs are worked incessantly for two or three days, the brine will 
be perhaps half a degree less strong; this is explained by the 
surface-springs getting mixed with the brine-water if the pressure 
from below becomes less. At Stoke, where the boring is better 
protected and cased with iron, to prevent the surface-springs getting 
in, no variation occurs in the brine. 
The Cheshire brine contains, I believe, from 34 to 36 per cent. of 
solid salt. The explanation of the decrease between the strength 
of the Cheshire and Worcester springs is, that the former have been 
overworked, the rock-salt not having been so thoroughly dissolved 
by the springs. 
Analyses of Droitwich brine, showing the solid constituents in 
the imperial gallon, have been made by various authorities. I 
give the more recent as follows :— 
Northcote, Phil. Mag. 1855, ser. 4, vol. ix. p. 33: 
Chioride.of sodimim . 56... 6 0) ee ee 19392-570 
Carbonate of magnesia ............ 33°501 
Carbonate of. Soda ed etic kas a Wee te 115:128 
Sulphaterof lime: cul. antici Belsee s 307°282 
Sulpliate of sodaie was. sineuldee 2p 46 309-097 
Traces of bromide of plagnesia 23:2... G20. 0% 
Salbspamae tmp. soalloriin aia meer dernr 20157:573 
* Mr. Bainbrigge, Droitwich Springs, chap. i. 
— a ea se ee 
