"In addition to the above-mentioned indispensable ingredients, the shampoo composition of the present invention may comprise ingredients customarily used for conventional shampoo compositions, for example, dissolving agents such as propylene glycol, glycerin and urea, viscosity adjusting agents such as ethanol, inorganic salts, higher alcohols, hydroxyethyl cellulose and hydroxypropyl cellulose, pe" . . . . . .