Bubble lights on the tree

I guess they are gone now.

The bubbling light was created in 1935 by Carl Otis, and his later patents improved the design over the years. The lights worked by heating a vial of low-boiling liquid (lightweight oil, in early versions) with a hidden incandescent bulb. Modern lights use dichloromethane as the fluid, but the design remains essentially unchanged. NOMA bought Otis’ designs but wasn’t able to market the whimsical lights until after World War II, first seeing sales success in 1947. To ensure the safety of lights, NOMA developed and marketed tiny fuses in 1951 that could be easily replaced. The small, vial-like devices are common to almost all decorative lights today.