  Tantalum arsenide, TaAs, is a prime example of a topological semimetal with
two types of Weyl nodes, W1 and W2, whose bulk signatures have proven elusive.
We apply Landau level spectroscopy to crystals with multiple facets and
identify -- among other low-energy excitations between parabolic bands -- the
response of a cone extending over a wide energy range. Comparison with density
functional theory studies allows us to associate this conical band with nearly
isotropic W2 nodes. In contrast, W1 cones, which are more anisotropic and less
extended in energy, appear to be buried too deep beneath the Fermi level. They
cannot be accessed directly. Instead, the excitations in their vicinity give
rise to an optical response typical of a narrow-gap semiconductor rather than a
Weyl semimetal.
