The heat liberated when $1.89\; g$ of benzoic acid is burnt in a bomb calorimeter at $25^\circ C$ increases the temperature of $18.94\; kg$ of water by $0.632^\circ C$. If the specific heat of water at $25^\circ C$ is $0.998 \;cal/g$ deg, the value of the heat of combustion of benzoic acid is
