  The recently proposed multiferroic state of the charge-transfer salt
{\kappa}-(BEDT-TTF)$_2$Cu[N(CN)$_2$]Cl [P. Lunkenheimer et al., Nature Mater.,
vol. 11, pp. 755-758, Sept. 2012] has been studied by dc-conductivity, magnetic
susceptibility and measurements of the dielectric constant on various,
differently prepared single crystals. In the majority of crystals we confirm
the existence of an order-disorder-type ferroelectric state which coincides
with antiferromagnetic order. This phenomenology rules out scenarios which
consider an inhomogeneous, short-range-ordered ferroelectric state.
Measurements of the dielectric constant and the magnetic susceptibility on the
same crystals reveal that both transitions lie very close to each other or even
collapse, indicating that both types of order are intimately coupled to each
other. We address issues of the frequency dependence of the dielectric constant
{\epsilon}' and the dielectric loss {\epsilon}'' and discuss sample-to-sample
variations.
