A barometer is a device that measures atmospheric pressure. You can see one on You Tube. The mercury barometer is made of a glass tube that is over 3 feet long !!! It is filled with mercury and inverted . At sea level, the mercury in the tube falls to a height of about 760 mm. This height is a direct measure if the atmospheric pressure pulling it down. For this reason, 760 mmHg is used as a value for atmospheric pressure. The bottom line on this problem is this.....As density increases , height decreases. If we replace water with a liquid six times as dense....the height attained will be 1/6 the height of water. Height and density are indirectly related.