238 Natural History of Volcanos and Harthquakes. 
common salt.* In my frequent excursions in the vicinity of the 
Laacher See and in the Eifel, I have never found any efflores- 
cence of salt either on the undisturbed or fresh broken lavas, and 
other products of the extinct craters in those districts. On the 
uncovered walls of trass, in the Brohi valley, efflorescences are, 
indeed, to be found, but they contain chlorides only as very sub- 
ordinate ingredients.+ The lixiviation of trass, basalt, and other 
volcanic rocks, also gives but a trace of common salt.{ That 
muriatic acid must have played a very insignificant part in the 
eruptions of these ancient volcanos, seems to be proved by the 
mineral springs which rise in their vicinity; for common salt is 
one of their least considerable components, indeed they frequently 
contain mere traces of it. This is the result of more than forty 
analyses of mineral springs in those regions, which I have under- 
taken during. these last few years. But these waters would ex- 
tract the chlorides from the voleanic masses through which they 
flow, if they existed in any considerable quantities in them, and 
would return impregnated with them to the surface. 
From all this we do not seem to be justified in considering the 
chlorides as the chief agents in voleanic phenomena, although it 
cannot be denied that they may, in some instances, co-operate in 
their production. It has even been supposed that the beds of 
ee ae 
* Loco cit. + Die vulkanischen Mineralquellen, &c. p- 243. 
¢ Idem, p. me as 247. 
= Many volcanos have produced considerable quantities of common § salt, as, for 
suvius, Hecla, &e. Also sal-ammoniac is found among the voleani¢ 
a 
of 
sublimations of Vesuvius and Etna, and almost exclusively in some V ei! 
the interior of Asia. Vauquelin found in a porous rock, gee considera 
ble part of the Puy de Sarcouy, in the chain of the Puy de Déme, 0 eis” 
iron-glance in that neighborhood. (Ann. des Mines. vi, p 98.) 
spar crystals i in the trachyte, colored sulphur-yellow by muriatic acid vapors © 
former time. Common salt also forms the chief ingredient in the thermal — 
of St. Wectaire, in the department Puy ee iy In the mineral springs of 
d'Or, Vichy, Chaudes-Aigues, Vals, &c., on the contrary, it is in very 5@ ph re 
tities. In the lavas of Etna 0.01 of muriatic mw? has been found. In basalt, ink: 
nedy found 0.01; Klaproth 0.0001 ; I, 0.00085 of muriatic acid. [al ebirge 
a acid in a steatitic substance in Prem ie Ste conglomerate of the Siebengen's 
Die vulcanischen phagprie corres = 277. oat this occurrence OF 
salt mines at Poza, near Burgos, in Old Castile, are situated in the cet 
ter, in which the latter collected various voleanic products. Journ. de 
Iv, p. 457 
