Pycnometer bottles are provided with non-mercury, red-spirit filled thermometers for facilities that are designated mercury-free. Bottles are designed with a special, medium length standard taper 10/18 joint and are retested for accuracy within ±0.2°C. Cap for side tube is medium length standard taper 5/12 and has a small vent near the top. Body is conical for maximum stability and capacity is within 10 percent of nominal shown on the flask. Each flask body is numbered for ready identification.