Section 78. A railroad corporation may purchase land for the location of its railroad within the limits of the route fixed under section twenty or twenty-one, and may also purchase so much more land as may be reasonably necessary for the proper construction and security of the railroad and the convenient operation thereof, for one or more new tracks adjacent to other land occupied by it by a track or tracks already in use, and for the purpose of cuttings, embankments, and for procuring stone and gravel, and for stations, car houses, roundhouses, freight houses, yards, docks, wharves, elevators and other structures.