Keeping your throat comfortable after hours of lecturing After lecturing for 3-4 hours my throat is often quite sore. Some days, I must lecturer for 6 hours (in past semesters, I've had some days which require lecturing for 8 hours). The problem is that for my later classes I have difficulty speaking comfortably. 

I drink a lot of water, don't smoke, and use lozenges from time to time (when I'm in pain).

Are there any other known (scientific or folklore) solutions to this problem of getting a sore throat after lecturing for 3-4 hours?
Make sure you can lecture without having to raise your voice, ever. When I did lecture a lot, I sometimes used a microphone even if the group was rather small, if only to be sure that I wouldn't raise my voice more than the minimal.
Drinking is good: I find that hot beverages heavily loaded with sugar are the best. I usually drink some light-flavoured tea (green tea, jasmine tea, …) with lots of sugar or honey. If the weather is hot, lemon-based drinks make you salivate more and help preventing dry sore throat.
Deal with your boss to avoid those horrible teaching conditions in the first place. He might not care that it's not in your best interest, but explain to him that it's not in the students' best interest either! (Sore throat aside, I don't know anyone who can teach with as much passion on the 8th hour as on the first.)