Glucose spatial arrangement
It's not certain properties, but a very careful observation if and with what products glucose reacts to other chemicals. Took many years. And even then Fischer did not know the absolute configuration, because at his time nobody knew the absolute configuration of anything. 

Only when the first absolute configurations were known from X-ray diffraction experiments, one could start comparing.

Today we can calculate the absolute optical activity via quantum mechanics, but Fischer solved the Glucose structure in 1891, that's a quarter century before quantum mechanics.