  Double Dirac materials are a topological phase of matter in which a
non-symmorphic symmetry enforces greater electronic degeneracy than normally
expected up to eightfold. The cubic palladium bronzes NaPd$_3$O$_4$ and
LaPd$_3$S$_4$ are built of Pd$_3$X$_4$ (X = O, S) anionic frameworks that are
ionically bonded to A cations (A = Na, La). These materials were recently
identified computationally as harboring eightfold fermions. Here we report the
preparation of single crystals and electronic properties of LaPd$_3$S$_4$.
Measurements down to T = 0.45 K and in magnetic fields up to $\mu$0H = 65 T are
consistent with normal Fermi liquid physics of a Dirac metal in the presence of
dilute magnetic impurities. This interpretation is further confirmed by
analysis of specific heat, magnetization measurements and comparison to density
functional theory (DFT) calculations. Through a bonding analysis of the DFT
electronic structure of NaPd$_3$O$_4$ and LaPd$_3$S$_4$, we identify the origin
of the stability of the anionic Pd$_3$X$_4$ framework at higher electron counts
for X = S than X = O, and propose chemical tuning strategies to enable shifting
the 8-fold fermion points to the Fermi level.
