148 Trans. Acad. Sci. of St. Louis. 
rather than real. Only the crust of the earth is com- 
monly considered; and the analysis of most meteoritic 
materials do not often show the true proportions of stony 
matter. | 
On the theory of meteoritic agglomeration the original 
and often the immediate source of ore materials cannot 
be so largely magmatic as it is vadose in nature. Quali- 
fied in some ways and somewhat strengthened in others, 
the general arguments of Forschammer, Sandberger, 
Winslow, Van Hise and Bain assume a new interest and 
an added value. The main shortcoming, if such it be, is 
merely in ascribing a yéle or principal origin of the ore 
materials to rock-weathering, when a somewhat broader 
interpretation of the facts and conditions seems neces- 
sary. 
The manner by which metallic substances of meteoritie 
origin may become incorporated with ore materials gen- 
erally is not an intricate one. After reaching the surface 
of the earth all cosmic dust and fragments must mingle 
with the soil, more or less quickly oxidize, and enter 
through means of the circulating ground-waters or other- 
wise sooner or later reach the deep-seated zone, in the 
same way as any of the heavier mineral particles liber- 
ated from the surface rocks through decomposition are 
supposed to do. The processes involved are essentially 
the same as for the changes and movements of rock-form- 
ing materials generally. The distinction to be made is 
merely that instead of all of the ore materials being de- 
rived from the breaking down of rocks of the lithosphere 
a very large proportion is regarded as coming from extra- 
terrestrial sources. 
In the course of the inward migration of ore materials 
temporary ore-bodies are often localized in the vadose 
zone, and even lower down. How much of these mater- 
ials is of recent extra-terrestrial origin and what propor- 
tion is really a product of rock decay is at the present 
moment difficult to estimate. Even dominant notions 
concerning ore-bodies seemingly directly associated with 
