In both the trunk and hood lamps there is a tiny vile of mercury under the bulb contact that when tipped completes the circuit. It is just like the mercury contact that used to be used in your wall mounted thermostat. I have no idea how the reproduction lights work, however, unless they have found a replacement liquid for mercury, I can't see how else they could function.
The interesting thing is that when we were kids, we played with mercury, and made copper pennies look like dimes by soaking the penny in the mercury. Back then, if you spilled some mercury, you just swept it up with a broom and a dust pan. Today, if you spill a drop of mercury in a school, they evacuate the building and call in a hazmat company to do the clean up for an outrageous amount of money. A few weeks ago, a friend asked me if I knew how to dispose of 20 +- pounds of mercury. I did a quick google search to see where he could sell it, and it appears that it is no longer purchased by the scrap metal dealers. 50 years ago, mercury was kept in steel bottles (flask) with a threaded cap, and when full, they weighed about 80 pound plus the flask. My dad was in the scrap metal business, and I routinely would pick up or drop off flasks of mercury at other dealers that were in the trade. In the 1960's I think it was worth about $190 for a flask. In 2016 it was over $4000 a flask.
