The emission of soot and thermal radiation by free turbulent diffusion flames of CO, H 2, Cl-b,, C2H 6, Calls, C2H4, and C2H 2 was studied over a range spanning the transition from forced convection to natural convection (burner diameters 0.7-10.9 mm, buoyancy Richardson ratios Ri L ~ lrgpcx~L3/4Go of 2-10,000, where L is flame length, t~ 0 is source momentum flux, pยฎ is ambient air density, and g is acceleration due to gravity. Both soot emission, expressed as the ratio Xs between soot output and carbon input, and radiant cooling, expressed as the ratio XR between radiant heat loss and chemical energy input (heat of combustion), rise with Ri L and tend to plateaus as natural convection becomes dominant (Ri L > 2000). However, it also appears that they fundamentally depend on parameters other than RiL, Xs being strongly correlated with the second Damkohler ratio or chemical loading factor and XR with the analogous thermal loading factors. The behavior observed is in reasonable accord with theoretical expectations. The plateau values of Xa at high R/L are 0.18-0.4 for the hydrocarbon fuels, and for Xs they are 0.0015--0.0045 for the hydrocarbons other than acetylene. Acetylene flames emit up to 100 times as much soot as the others. Buoyancy is unimportant below Ri L = 200 since Xs and XR ate then independent of burner orientation (vertical or horizontal). Also, the soot emission for hydrocarbon fuels other than acetylene seems to stablize, indicating รs = 0.0003 at Ri L < 200.