Of the 19,000 houses in Venice only 6000 have drains and sinks, all the others discharge sewage through pipes directly or indirectly into the canals.
No doubt large numbers are devoured by insectivorous birds, mammals and reptiles, but the mortality due to them and other foes sinks into insignificance beside that caused by the persecution of hymenopterous insects of the families Ichneumonidae and Pompilidae, especially of the latter, many species of which systematically ransack the country for spiders wherewith to feed their young in the breeding season.
Thereafter it broadens out and becomes the high table-land of Galilee, Samaria and Judaea, and gradually sinks into the plateau of north Sinai.
Either common salt or strong brine in measured quantity is added to the charge, and, the soap being insoluble in such salt solution, a separation of constituents takes place: the soap collects on the surface in an open granular condition, and the spent lye sinks to the bottom after it has been left for a short time to settle.
In some parts it rises into irregular uplands and elevated plains, interspersed with detached rocks of granite; in others it sinks into marshy lowlands, which frequently remain under water during the rainy season.