When M. Perrin first visited Ancor-Viat, he saw nothing of its ancient splendor; for in "Indian China," as in Central America, monuments of large dimensions and great beauty are often unknown to the people who dwell within a few hundred yards of them. The concourse of intelligent and wealthy travellers alone teaches ignorant natives the value of their own surroundings. On his second journey M. Perrin's attention was directed to the ruins by a curious circumstance. The King of Kokien pays a yearly tribute to the King of Siam in kind, and among the articles saltpetre figures largely. In the whole of India beyond the Ganges--in the Birman Empire, Siam, Malacca, and Annam--the people, children-like, have a passion for fireworks, and consequently consume a large quantity of saltpetre. Now the excrement of bats and night-birds that haunt in great abundance the cities of the dead furnishes, it seems, a copious supply of this substance, and is, in fact, as fruitful in the production of squibs and rockets as guano--the dung of Peruvian sea-birds--is in the cultivation of corn and rye. It is collected by malefactors who work in chains, and is dissolved in water mixed with ashes. After some days the water and ashes, with the macerated dung strongly impregnated with ammonia, is passed through tight sieves, and exposed in big caldrons to the action of huge fires. {136} The entire substance then evaporates leaving behind it crystals of saltpetre. The East was famous of old for the manufacture of nitre; and we have all have noticed how it forms spontaneously on the walls of stables, slaughter-houses, cellars, and the like, from the decomposition of animal matter, and even from the breath and sweat of beasts. No wonder M. Perrin was struck as a foreigner by the strange spectacle of convicts collecting bird-dung. The birds of night have a strong affinity for ruins, and crumbling towers and terraces are--to use an expression of Virgil's-- "Dirarum nidis domus opportuna volucrum."