DIU  , an

island and town of India, belonging to Portugal, and situated at the southern extremity of the peninsula of Kathiawar . Area of district, 20 sq. m . Pop . (19oo) 14,614 . The anchorage is fairly protected from the sea, but the depth of water is only 3 to 4 fathoms . The channel between the island on Diu and the main-land is navigable only by fishing boats and small craft . The town is well fortified on the old system, being surrounded by a wall with towers at regular intervals . Many of the inhabitants are the well-known Banyan merchants of the east coast of Africa and Arabia . Native spirits are distilled from the palm, salt is made and fish caught: The trade of the town, however, is decayed . There are remains of several fine ancient buildings . The cathedral or Se Matriz, dating from 16o1, was formerly a Jesuit college . The mint, the arsenal and several convents (now ruined or converted to other uses) are also noteworthy .

The Portuguese, under treaty with Bahadur Shah of

Gujarat, built a fort here in 1535, but soon quarrelled with the natives and were besieged in 1538 and 1545 . The second siege is one of the most famous in Indo-Portuguese history, and is the subject of an epic by Jeronymo Corte Real (q.v.) . See R . S . Whiteway, Rise of the Portuguese Power in India (1898) . DIURETICS (from Gr . &a, through, and ofipeiv, pass urine), -DIVAN 325 the name given to remedies which, under certain conditions, stimulate an increased flow of urine . Their mode of action is various . Some are absorbed into the blood, carried to the secretory organs (the kidneys), and stimulate them directly, causing an increased flow of blood; others act as stimulants through the nervous system . A second class act in congested conditions of the kidneys by diminishing the congestion . Another class, such as the saline diuretics, are effectual by virtue of their osmotic action . A fourth class are diuretic by increasing the blood pressure within the vessels in general, and the Malpighian tufts in particular,—some, as digitalis, by increasing the strength of the heart's contractions, and others, as water, by increasing the amount of fluid circulating in the vessels .

Some remedies, as

mercury, although not diuretic themselves, when prescribed along with those which have this action, increase. their effect . The same remedy may act in more than one way, e.g. alcohol, besides stimulating the secretory organs directly, is a stimulant to the circulation, and thus increases the pressure within the vessels . Diuretics are prescribed when the quantity of urine is much diminished, or when, although the quantity may be normal, it is wished to relieve some other organ or set of organs of part of their ordinary work, or to aid in carrying off some morbid product circulating in the blood, or to hasten the removal of inflammatory serous exudations, or of dropsical collections of fluid . Caffeine, which is far the best true diuretic, acts in nearly every way mentioned above . Together with digitalis it is the most efficient remedy for cardiac dropsy . A famous diuretic pill, known as Guy's pill, consists of a grain each of mercurial pill, digitalis leaves and squill, made up with extract of henbane . Digitalis, producing its diuretic effect by its combined action on heart, vessels and kidneys, is much used in the oedema of mitral disease, but must be avoided in chronic Bright's disease, as it increases the tension of the pulse, already often dangerously high . Turpentine and cantharides are not now recommended as diuretics, as they are too irritating to the kidneys .