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The spectrum of visible emission from tritiated acetylene gas in closed cell with no external excitation has been recorded. Two forms of gas were used: (1) $C2HT$, synthesized by a modified Wilzbach process and mixed with $C2H2$: (2) mixtures of $C2H2$ and $T2$. The gases were held in stainless steel cells of about $20cm3$ volume with sapphire windows. Pressures were 100-300 Torr. Emitted photons were analyzed with a 1/2-m monochromator, an RCA 31034A-12 photomultiplier, and standard counting electronics. The spectra exhibit the well-known Swan bands of $C2$ and a broad band which may be $C2H$. The CH 431.5 nm band was not prominent. The emission results entirely from the radioactivity of the gas. The energy of the fast beta produced in the tritium decay $T+3He++\beta -+\upsilon -$ is collisionally degraded in a variety of secondary processes. The observed spectrum can be understood only by examination of the complete degradation energy spectrum.