2 OBSERVATIONS AND DATA REDUCTION
2.1 Mid-infrared data
2.2 Far-infrared data
2.3 CO data
2.4 HI data
2.5 Convolution kernels
2.6 Abundance information

4 THE CO J=(3-2)/J=(1-0) RATIO AND THE CONVERSION FROM LINE INTENSITY TO MOLECULAR GAS SURFACE DENSITY

5 COMPARISON OF ATOMIC GAS, MOLECULAR GAS, AND DUST SURFACE DENSITIES

6 COMPARISON OF PAH, CO J=(3-2), AND HI EMISSION

7 CONCLUSIONS