The commission now in charge of the soldiers' orphans' schools are empowered to purchase not more than one hundred acres of ground, the title of which shall be vested in the commonwealth, and to erect buildings thereon, equipping the same with shops, tools, et cetera, for industrial training, as well as for the educational course, and for the maintenance of the soldiers' orphans, first taking security for the faithful performance of all contracts, and for the completion of the building and buildings in a substantial, good and workmanlike manner.