Figure 1.

(Propane)/(n-Butane) ratio emerging from Floyd shale under helium flow at 50°C [1]. The ratio is ratio of propane and n-butane concentrations (ppm vol) in effluent gas stream at indicated times. The line is the linear regression line, C3/C4 = 2.24 (time) + 0.0026, R² = 0.76.