There is a tendency to utilize underground space for the less ornamental purposes of civilization; there is the Metropolitan Railway in London, for instance, there are new electric railways, there are subways, there are underground workrooms and restaurants, and they increase and multiply.
Polystyrene can be naturally transparent, but can be colored with colorants. Uses include protective packaging (such as packing peanuts and CD and DVD cases), containers (such as clamshells), lids, bottles, trays, tumblers, and disposable cutlery.
This resin code on a plastic container indicates that BPA may have been used in its manufacture. BPA is a chemical component present in polycarbonate plastic used in the manufacture of certain beverage containers and most food can liners. BPA-based plastic bottles are clear and tough. In cans, BPA-based liners form a barrier between the food and the can surface that prevents corrosion of the can and migration of metal into the food.