One of my research projects research focuses on the nature of diffuse interstellar clouds. I use infrared and radio observations to measure the amount of dust and gas, which showed that there are clouds of molecular gas that are not bright in CO. This material is now known as "dark gas" (named by a gamma-ray astronomer). In my work, I identified isolated, nearby, 100 solar mass clouds that are not forming stars. The first paper identified the clouds and made an assessment of their contents using Planck to measure the dust content and Arecibo to measure atomic gas. We found the locations of excess infrared emission are spatially coherent and identified three hypotheses for the nature of the apparent "dark gas". The second paper showed the "dark gas" is not cold, atomic gas, which would have shown 21-cm absorption in new Arecibo observations. The third paper examined the effect of dust property evolution in diffuse clouds, which contributes to the apparent far-infrared excess but falls short of explaining all of it, which still requires molecular gas. The fourth and final paper of the series examined pairs of diffuse clouds with significant far-infrared excess and compared them to shock models, making the point that motion of the clouds through their surrounding medium leads to shocks that enhance molecule formation.