Abstract: There is provided with an etching method using an etching apparatus. Four arms can be positioned in a direction substantially from a center of the stage toward a peripheral portion with an angle difference of about 90°. Etchant is supplied to a first position nearest to the center of the object which is rotating, from a first etchant supply nozzle placed on a first arm. Etchant is further supplied to a second position second nearest to the center of the object, from a second etchant supply nozzle placed on a second arm. The second arm is substantially symmetrically positioned with respect to the first arm and the second arm has an angle difference of about 180° with respect to the first arm.

Abstract: Fibrous compounds having a ratio of length to diameter of at least 10 of the formula MO.TiO.sub.2 wherein M is a bivalent metal and processes for preparing these compounds are described. Preferably M is selected from the group consisting of barium, strontium, calcium, magnesium, cobalt, lead, zinc, beryllium, and cadmium. The processes for preparing the compounds utilize fibrous potassium titanate hydrates or fibrous titanium dioxide hydrates both having a ratio of length to diameter of at least 10 as the starting material to prepare the compounds.