Abstract: An ink composition includes: first particles which are insoluble and dispersed in an aqueous dispersion medium, a polarity of the first particles being one of positive and negative; and second particles which are insoluble and dispersed in the aqueous dispersion medium, the second particles including both a cationic group and an anionic group, the second particles having a zeta potential that changes along with a change in pH of the aqueous dispersion medium, percentage of a water-soluble component in the second particles being not higher than 5% by mass.

Abstract: Means of stringing trolley wires comprises a supporting portion, resilient portions and a sliding portion. The supporting portion comprises a box member having an opening at the bottom thereof, and each of the resilient portions comprises a spring member and a supporting rod which protrudes through the opening of the box member and is adapted to move and incline in compliance with the condition of the sliding portion while the sliding portion comprises a pair of long ears and long trolley wires clamped by the pair of the long ears. The long ears of the sliding portion are supported at predetermined intervals by a plurality of the supporting rods of the resilient portions.