AVtC Hypothesis of Earth-Origin. — Fairchild. 103 
and Stiibel. Nearly ten years ago the view was emphasized 
before this society by Dr. Lane,* but the repressive effect of 
the old hypothesis has prevented the full recognition of the 
truth and of its value. However it has not been shown how, 
under the nebulous condition of the globe, the molten nucleus 
could obtain a grasp on its occluded gases. 
The new hypothesis simplifies the problem not only by mak- 
ing the volcanic water and the accompanying vapors indigen- 
ous to the earth's mass, but by giving a plausible explanation 
of how they came to be a part of the magma. Volcanoes are 
at once the outlets for relief of accumulated vapor pressure and 
a source of ocean and atmosphere supply. With the reduc- 
tion in volume of steam and the lighter gases the heavier and 
nonexplosive gases become more evident, and then occur the 
later phenomena known as fumaroles, solfataras, sofifioni and 
mofettes. It may be that in the volcanic reservoirs 'the several 
vapors are arranged, as in the atmosphere, according to their 
specific gravity. 
The existence of carbon dioxide springs (mofettes), such 
as the "dog grotto" near Naples and the "valley of death" in 
Java, are well explained under the new hypothesis. Under the 
old view the mofettes were compelled to derive their carbon 
from limestones and carbonaceous shales. The dog grotto with 
its strong and continuous flow for some thousands of years, 
probably, would imply a subterranean limekiln of immense ex- 
tent. Shales could not furnish the supply as they are not suffi- 
ciently permeable. This topic will come up again in discus- 
sion of the hydrocarbons. 
The chlorides and other haloid salts in volcanic emanations 
have been assumed to come from sea water or from marine 
sediments where the sea had left them. The variety of gases in 
volcanic eruptions can not all be derived from atmospheric 
water, and some of them are not contained in sea water. The 
abundant sulphur compounds have not been accounted for at all. 
The resemblance of the mineral contents of the sea to the vol- 
canic products lies in the fact that the ocean is itself the pro- 
duct of volcanism. The old view has put the effect for the 
cause. 
• A. C. Lanb. "GcoloRic activity of the earth's originally absorbed gases." 
Buil. Geol. Soc. Am., vol. v. pp. 259-280. 
