Abstract: A sample gas cell and casing system for use in sampling and analysis of gas samples by Raman light scattering comprises a tubular casing means forming a longitudinal bore, a gas sampling cell transversely mounted in the tubular casing means relative to the longitudinal bore with the gas sampling cell protruding at either end through the tubular casing. The gas cell has opposing windows at the ends which are located outside the tubular casing and are interconnected by a continuous sidewall passing through the casing. The end windows and sidewall define a longitudinal gas chamber having an axis perpendicular to the axis of longitudinal bore in the tubular casing. At least a portion of the continuous sidewall located inside the casing has window means through which scattered light may pass. The cell further contains inlet and outlet means communicating with the chamber to pass a sample gas through said cell.