1884.] On the Evidence that the Earth's Interior is Solid. 685 
careful experiments are needed. Practically this seems to be the 
case in nature of the Kilauea lavas at least. 
The question which now presents itself is: What are the prob- 
able components of the earth’s interior ? 
So far as can be told from petrographical study, it appears 
probable that the portion of the interior mass lying nearest the 
center, concerning which we have any data, is composed of iron! 
either with or without nickel. As we recede from the central 
portions pyrrhotite is united with the nickel and iron. Then 
these minerals are found united with olivine or olivine and ensta- 
tite in varying proportions, until a portion is reached composed 
almost entirely of one or both of these silicates, with or without 
diallage. This portion passes on into the common basaltic rocks, 
then into the andesites and so on outward into the trachytic, 
thyolitic, and jaspilitic forms. 
However true this order may be for the liquid earth, that is, 
the liquid material would form rocks of this character, it is cer- 
tain that in the solid portions these materials are interlaced now 
with one another in every conceivable way, and in the chemical 
w sedimentary deposits they have now been intimately min- 
ed 
What may be the composition of the earth’s mass nearer the 
center, if there be any, besides the iron and nickel, we have no 
clue, except that it may be some of the rarer elements now found 
mixed with the iron. l 
Now, while we know experimentally almost nothing of the be- 
havior of such materials, as probably compose the earth’s interior, 
under the combined action of heat and pressure, it seems most 
Probable, from Thomson’s “ thermo-dynamic law ” and the exper- 
'ments on their relative hot solid and liquid densities, that the 
Pressure to which they are subject would cause them to liquify 
at a lower temperature in the earth’s interior than on its surface. 
X may also be justly claimed that if the earth’s interior is solid, 
= liquefaction may be brought about by an increase instead of a 
diminution of pressure. In this way a sinking area loaded with 
Sediments might thus liquify the rock beneath it. Is this not as 
stent a view as the theory of liquefaction through the remo- 
val of pressure > 
lw: : ; 
Bacon Metallic Wealth of the United States, 1854, p- 434, Judd’s Volca- - 
181, Pp. 307-324. 
