Observations of the ignition phase and measurements of the ignition delay and volatile combustion times have been made for 24 nearly-spherical corncob particles having diameters in the range of 300 to 1500 microns. Each particle was attached to a finely-tipped quartz needle and then individually injected into a heated furnace where ignition and combustion occurred. Analysis of the volatile burning time measurements focuses on obtaining a rate constant which accounts for the observation of varying densities among particles. The results are compared to a previous analysis in which the particle density was assumed to be constant. Analysis of the ignition data consists of identifying the dependence of the ignition delay time on the particle size and density and identifying the rate controlling mechanism for ignition delay. Both the volatile burning times and the ignition delay times are shown to be functions of the product of the initial particle density with the square of the initial particle diameter, indicating that convective heat transfer to the particle is the rate controlling mechanism for both processes.