XXXIV SEVENTH REPORT—1837. 
great depths cannot yet be considered as absolutely determined, on ac- 
count of the imperfection of the modes of obtaining unmixed water front 
such points. The water of springs is more especially the object of Dr. 
Daubeny’s Report. 
In considering the saline contents of mineral springs, he gives some 
ingenious speculations on the origin of these salts; especially of the 
carbonate of soda, of the sulphates, and of boracic acid. The common 
salt he derives from the same source as the saltness of the sea; and he 
considers rock-salt as a deposition from the waters of the ocean; a view 
confirmed by the presence in saline deposits of iodine and bromine—ele- 
ments first detected in marine productions. Dr. Daubeny regards the 
absence of these two bodies in the lowest and purest bed of the Cheshire 
rock-salt while they abound in the upper saliferous beds, as proofs that 
rock-salt was deposited from a saturated solution. The salts of io- 
dine and bromine, as well as the earthy muriates, from their greater 
solubility, would remain longer in solution ; and thus be mingled with 
the more hasty mechanical deposits from the waters. The brine 
springs of Droitwich, which are found to contain neither iodine nor 
bromine, he also considers as derived from a salt deposited from a sa- 
turated solution. 
The siliceous earth, so often detected in thermal springs, he con- 
ceives to be dissolved by alkaline matter, aided by a high temperature. 
Both alkali and silica may be afforded by felspathic rocks; and Dr. 
Daubeny conjectures, that silica may be more soluble in hot water at 
the moment of its separation from its combinations in the rock, or ere 
it has its aggregation increased, by assuming the crystalline texture. 
He states, that it may be interesting to try, whether hot water has a 
stronger action on such bodies as opal, in which the molecules do not 
seem to have a true crystalline arrangement, than on quartz. Since I 
came this time to Liverpool, I subjected a fragment of wood-opal for 
fourteen days to a temperature estimated about 280° Faht., in the boiler 
of a fixed steam-engine ; but it had neither lost nor gained the smallest 
weight in that time. 
The author combats the opinion of Anglada on the origin of the or- 
ganic matter termed Glairine, now found to be a very common ingre- 
dient of thermal springs. This substance Anglada supposes, with little 
probability, to be derived from the interior of the earth ; while the ob- 
servations of our author on this substance, as collected from above fifty 
springs, especially from the thermal sources of the Pyrenees, show, that 
Glairine is probably derived from the decomposition of organic bodies, 
such as conferve and infusory animaleules. 
