Coal tar is a by-product of the production of coke and coal gas from coal. The Victorians found uses for coal tar and its fractions as a preservative for railway sleepers (creosote), in the construction industry (pitch), and for medicinal purposes. Later, coal tar became a component of the first sealed roads.
I imagine the Victorians moved their tar in bulk quantities by rail, but the recognised reference books on tank wagons give few details before the beginning of the oil industry in the following century. Perhaps, there were no standard designs of wagons. We can suppose the Victorians built their tank wagons in much the same way as other wagons, with a
