Although not covered by the rules, sulfur dioxide also could drop up to 90 percent because it would be filtered out by the same technology that controls hydrochloric acid.
These small tablets contain one drop of hydrochloric acid and they last about four hours.
这些小片剂每片含有一滴盐酸，药效持续四个小时左右。
3
Dissolve a pinch of silver and mercury in a solution of nitric acid, drop in a lump of metal amalgam, and soon a spidery, glittering "Tree of Diana" will form on the glass.