Is it legal to transport hydrochloric acid?

Answer 1

You have to follow certain safety codes. On each compound's MSDS (Material Safety Data Sheet) there is a section for transportation information.

the code is split into Packing groups, Hazard Classes, and transport categories.

Each packing group, hazard class and transport category outlines the safety measures taken when transporting the material and the exceptions taken when considering the safety measures required.

Here is the glossary definition of each class:

http://msds.chem.ox.ac.uk/glossary/un_hazard_codes.html

If you contact your post office or other transport venue, they can tell you more on what precautions and packing you must have in order to safely ship hydrochloric acid.