Two small vessels are connected to a U-tube mercury manometer (relative density of 13.56). The connecting vessels are filled with alcohol (relative density of 0.82). The vessel at higher pressure is 2.0 m lower in elevation than the other. What is the pressure difference between the vessels if the difference in levels of mercury menisci is 225 mm? If an inverted U-tube manometer containing a liquid of relative density 0.74 were used, what would have been the manometer reading for the same pressure difference?