The earth is a bubble?

The temperature of some magma
exiting volcanoes is higher than the melting point of iron. It seems
reasonable that the magma would have cooled some on the way to the
surface and would therefore have been even hotter where it originated
from underground. I am thinking that the earth is really a bubble of
molten magma and metals or whatever, surrounding gases undergoing
fusion at extremely high temperature on the inside (of
course the bubble is surrounded by a solid crust formed by cooling of
the surface of the bubble). Change of pressure of the gases
inside the bubble as they undergo fusion to heavier elements (such as
carbon and oxygen) could cause seismic activity on the surface and
provide an explanation for the carbon dioxide emitted by volcanoes. The
bubble may be stratified with magma on the outside of more dense molten
metals.