Helium gas at \(25^{\circ} \mathrm{C}\) and 6 bar is contained in a glass cylinder of \(100-\mathrm{mm}\) inside diameter and \(5-\mathrm{mm}\) thickness. What is the rate of mass loss per unit length of the cylinder? Assume the properties of glass to be those of \(\mathrm{SiO}_{2}\).