A round-bottomed glass flask having a long neck; a bolthead.

A vessel with a round bottom and a long, slender neck, used for distillation* or for heating solutions. The modern Florence flask may have a round or flat bottom.

A matrass (mod. Latin matracium) is a glass vessel with a round or oval body and a long narrow neck, used in chemistry as a digester or distiller. The Florence flask of commerce is frequently used for this purpose.