use the vial cap to top off the vial and form a meniscus. STEP NINE Screw the cap onto the vial with the Teflon side of cap liner face down, in contact with the water. Roll or shake vial to fully mix ascorbic acid. Carefully uncap vial and add 4 drops of HCL to the vial. NOTE: HCLmay cause burns so use proper eye, hand, and clothing protection