  We explore the equations of state and other properties of various quantum
fluids (3He, 4He, their mixtures, and H_2) confined within individual carbon
nanotubes. Above a threshold number of particles, N_a, the fluid density near
the axis begins to grow above a negligibly small value. The properties of this
axial fluid phase are sensitive to the tube size and hence to the transverse
compression in the case of a bundle of nanotubes. We consider He at zero
temperature and H_2 at low temperatures.
