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 of the article on the pipe organ, the ancient hydraulis was played by hand, not automatically by the water-flow; the keys were balanced and could be played with a light touch, as is clear from the reference in a Latin poem by Claudian (late 4th century), who uses this very phrase ("magna levi detrudens murmura tactu . . . intonet", “let him thunder forth as he presses out mighty roarings with a light touch”) ("Paneg. Manlio Theodoro," 320–22). Typically, water is supplied from some height above the instrument through a pipe, and air is introduced into the water stream by