Electrostatic series??

If two substances are rubbed together the former in series acquires the positive charge and later, the –ve.

 (i) Glass

 (ii) Flannel

 (iii) Wool 

 (iv) Silk

 (v) Hard Metal

 (vi) Hard rubber 

 (vii) Sealing wax

 (viii) Resin

 (ix) Sulphur