The diameter of an air bubble which was initially 2 mm , rises steadily through a solution of density $1750 \mathrm{~kg} \mathrm{~m}^{-} { }^3$ at the rate of $0.35 \mathrm{cms}^{-1}$. The coefficient of viscosity of the solution is $\_\_\_\_$ poise (in nearest integer). (the density of air is nealiaible)