Molecular sieves can react with ZnCl2. Have you pure CHCl3? Usually it containes some EtOH. I recommend a Schlenk flask, Wernerglas in Sweden has a good model.
this is the best I have found
Assay (GC, on anhydrous basis) 99.9-100 %
Appearance Clear colorless liquid
Acidity (as HCl) 0-0.001 %
Residue after evaporation 0-0.0005 % w/w
Stabilizer (Amylene) 0.003-0.006 % w/w
Water (KF) 0-0.005 % w/w