GENESIS OF THE ALKALINE ROCKS 113 
more likely cause than the action of the greatly overworked 
juvenile gases alone. 
Migration of free volatile materials from country rock.—The addi- 
tion of resurgent gas to a magma does not depend entirely on the 
solution of country rock as such. Elsewhere the writer has empha- 
sized the high probability that connate water and other volatile 
substances in the country rock may be independently driven into 
injected magma.* An illustration is found in the so-called white 
traps of Scotland. Day holds that the otherwise typical basalt 
of the Cheese Bay sill has been reduced, whitened, and rendered 
vesicular by bituminous emanations from the intruded shale.’ 
Relevant experiments ——Controlled experiments on the chemical 
effects of dissolving limestone, dolomite, shale, etc., in subalkaline, 
particularly basaltic, melts areneeded. They are sure to be difficult 
experiments if the conditions of nature are even approximated. 
Failing such direct tests, the information accruing from certain 
attempts to extract potash from feldspar commercially is not with- 
out value. According to Ross, if potash feldspar, lime (CaO), and 
water are heated together in a bomb at 300° C. and under a pres- 
sure of ot atmospheres, the potassium is leached from the min- 
eral and, as caustic potash, taken into the water solution. The 
amount of the leaching depends on the proportion of lime in the 
mixture until about three grams of lime are mixed with one gram 
of feldspar, when practically all of the potash is found to be leached. 
In the same volume where Ross’s paper appears (p. 646), R. J. 
Nestell and E. Anderson illustrate with actual analyses the strong 
volatilization of both potash and soda in the kilns of cement-mills. 
They agree with Ross in holding that the presence of lime tends to 
prevent a recombination of the alkalies with the silica of the original 
kiln charge. 
Such experiments do not, of course, prove anything definite 
about magmatic reactions, but they do encourage the speculation 
that, in the presence of juvenile and resurgent water, carbon 
dioxide, and other volatiles, the alkali oxides may in a sense be 
tR. A. Daly, Amer. Jour. Sci., XLIII (1917), 445. 
2T. C. Day, Trans. Edin. Geol. Soc., X (1916), 249, 261. 
3 W. H. Ross, Jour. Indust. and Eng. Chem., 1X (1917), 467. 
