  Context: KELT-9 b exemplifies a newly emerging class of short-period gaseous
exoplanets that tend to orbit hot, early type stars - termed ultra-hot
Jupiters. The severe stellar irradiation heats their atmospheres to
temperatures of $\sim 4,000$ K, similar to the photospheres of dwarf stars. Due
to the absence of aerosols and complex molecular chemistry at such
temperatures, these planets offer the potential of detailed chemical
characterisation through transit and day-side spectroscopy. Studies of their
chemical inventories may provide crucial constraints on their formation process
and evolution history.
  Aims: To search the optical transmission spectrum of KELT-9 b for absorption
lines by metals using the cross-correlation technique.
  Methods: We analyse 2 transits observed with the HARPS-N spectrograph. We use
an isothermal equilibrium chemistry model to predict the transmission spectrum
for each of the neutral and singly-ionized atoms with atomic numbers between 3
and 78. Of these, we identify the elements that are expected to have spectral
lines in the visible wavelength range and use those as cross-correlation
templates.
  Results: We detect absorption of Na I, Cr II, Sc II and Y II, and confirm
previous detections of Mg I, Fe I, Fe II and Ti II. In addition, we find
evidence of Ca I, Cr I, Co I, and Sr II that will require further observations
to verify. The detected absorption lines are significantly deeper than model
predictions, suggesting that material is transported to higher altitudes where
the density is enhanced compared to a hydrostatic profile. There appears to be
no significant blue-shift of the absorption spectrum due to a net day-to-night
side wind. In particular, the strong Fe II feature is shifted by $0.18 \pm
0.27$ km~s$^{-1}$, consistent with zero. Using the orbital velocity of the
planet we revise the steller and planetary masses and radii.

Earth and Planetary Astrophysics