Dialysis blocks the passage of larger substances (for example, red blood cells, large proteins). This replicates the filtering process that takes place in the kidneys when the blood enters the kidneys and the larger substances are separated from the smaller ones in the glomerulus. The two main types of dialysis, hemodialysis and peritoneal dialysis, remove wastes and excess water from the blood in different ways. Hemodialysis removes wastes and water by circulating blood outside the body through an external filter, called a dialyzer, that contains a semipermeable membrane. The blood flows in one direction and the dialysate flows in the opposite.
Water organ these only the one at the Palazzo del Quirinale has survived. Kircher's illustration in "Musurgia universalis" (1650), long thought to be a fanciful representation of a hypothetical possibility, has been found to be accurate in every detail when compared to the organ grotto at the Quirinale, except that it was reversed left to right. There are still traces of the instrument at the Villa d'Este but the mineral-rich water of the river which cascades through the organ grotto has caused accretions which have hidden most of the evidence from view. In the early 17th century, water organs were built in