Complex sentence: When using a gas syringe you must not get it wet.Dry of the inside tube with a paper towl so that the movement of the syringe is smoother and more reliable when gasses are being measured.
Split into simpler sentences: When using a gas syringe you must not get it wet. Dry off the inside tube with a paper towl so that the movement of the syringe is smoother and more reliable when gasses are being measured.