Cac'odyle, or Cac'odyl, kǎk'ō-dil, -dil (Gr., "having a bad smell"), in chemistry, a monad radical having the formula As(CH3)2, and of special interest to the chemist because it was the first radical known in which a metal or a metalloid is combined with an organic base. The compound As: (CH3), which was discovered by Bunsen in 1837, and which can exist in the free state, is often called cacodyle, but it is more correctly known as dicacodyle since its molecule consists of two cacodyle radicals. Dicacodyle is obtained in the pure state by heating cacodyle chloride with zinc in an atmosphere of carbon dioxide, but a mixture of cacodyle oxide and dicacodyle (known formerly as Cadet's fuming liquid) may be obtained by distilling potassium acetate with an equal weight of arsenic trioxide. Mercuric oxide (HgO) converts both of the constituents of Cadet's liquid into cacodylic acid, (CH3)2ASO(OH); and this, in turn, is converted into cacodyle chloride, As(CH3)2C1, by the action of corrosive sublimate and fuming hydrochloric acid. Cacodyle oxide (known also as alkarsin) may be obtained in the pure state by distilling the chloride with an aqueous solution of caustic potash in an atmosphere of carbon dioxide. Dicacodyle is a colorless liquid, heavier than water, boiling at 338° F., and characterized by an intensely disagreeable smell suggestive of garlic. It takes fire spontaneously when exposed to the air, and its vapors are extremely poisonous. Dicacodyle is known to the chemist as tetra-methyl di-arsenid.

Cacoëthes, an ill and irrepressible propensity or labit. The term is chiefly used in the phrase cacoëthes scribendi, an itch for writing books.

Cacolet, kǎk'o-la, a contrivance somewhat resembling a double arm-chair, or in other cases like a bed, fixed on the back of a mule or horse, for carrying sick persons or travelers in mountainous countries. Cacolets have also been used in warfare for carrying wounded soldiers.

Cacomistle, kǎk-ō-mis-ël, a small Mexican animal (Bassariscus astutus), closely related to the raccoon, and similar in its haunts and habits. It is slender, about 10 inches long, with a sharp, fox-like face, large bright eyes surrounded with light patches, and erect ears. The long, soft fur is light brown above, darker along the back; the under parts are white, and the bushy tail has six broad white rings running around it. It is often tamed, and is called the American "civet-cat" by the miners, who keep it as a pet and mouser.

Cacongo, kä-kong'gō, or Kakongo, a former district of Guinea, Africa, extending along the South Atlantic Ocean, in lat. 5° S., just north of the mouth of the Congo. The Cacongo River enters the sea in lat. 5° 12' S. This territory was claimed by the Portuguese, and Cabinda is the northern part of it; the south and east to the Congo have been absorbed in the Congo Free State.

Cactacea. See CACTUS.

Cactus, the common name for all members of the family Cactaceæ, an order of calycifloral dicotyledons, found in luxuriance in the arid sections of the United States and South America. Both the Greeks and Latins were perfectly familiar with this curious monstrosity of nature,

the word being KάKTOS in Greek and cacti in Latin. Linnæus included all this species under the one generic term cactus, of which there are about 1,000 species. One of these is a native of Ceylon, with which the ancients were familiar. But the true home of the cactus is in America, where our otherwise arid plains and deserts are covered with it. Like the watermelon, it has the faculty of absorbing into itself from the air and earth, a vast bulk of water, making its stem most succulent. For this reason it is often called "the spring of the desert." The Mexicans are most proficient in finding uses for this plant, making drink, food, and clothing from it. Many medical scientists attribute the freedom of these people from diabetes and other forms of kidney trouble to the free use of the sap of the cactus as a beverage. It is said to be a sure cure for the earlier stages of this trouble. From the agave, a species of a similar family, pulque and mescal, the two national drinks of Mexico, are brewed. That vast arid plateau of which Arizona, portions of New Mexico and Texas are a part, is covered with countless varieties of cactus. The Spanish-speaking people call some of this territory "Llano Estacado" - the staked plain — because of the multitude of dead stalks of the Cercus giganteus which rise to a height of sometimes 20 feet. These bloom but once, usually at the end of 10 or 12 years of slow growth, and then__ die, the stalks remaining in the ground. These are commonly called the "century plant," from the supposition that they bloom but once a century. The yucca, another species, often grows to more heroic proportions, even, sometimes reaching its uncouth branches upward for 30 or 40 feet. The horses and cattle on these southern ranges find in the cactus relief from thirst, being expert in breaking down the spines, with which it is covered, dian tribes of the Southwest use these spines with their hoofs. The Navajo and other Inas needles with which to weave their marvelous blankets. As the date-palm is to the Arab, so is the cactus to the Indian,- a weird provision of the Creator to overcome obstacles for man. The most common kind, met with all over western America, is the Opuntia coccinellifera, which grows as a succession of small, oblong, thick leaves, covered, like most of its kind, with many spines. Because of these spines it is used for hedges, particularly the variety called "prickly pear." The cochineal insect feeds on these Opuntia plants, making it of commercial value. The cultivation of the cactus family in northern hot-houses and parks is becoming more and more popular, as the species is capable of being trained into wonderfully grotesque shapes, producing flowers of great size and beauty. In the new botanical gardens at Bronx Park, New York city, are perhaps some of the finest illustrations of this training. The seaside resorts of California (like Coronado Beach) are beautified with countless specimens of cactus, as are all the public parks and private gardens of that State. Even the birds find a use for the cactus, for a variety of wren builds and lives upon it. Our American deserts would lose much of their attractive charm were it not for this humble vegetation in their lava-beds and sand.

The flowers and stems of the night-blooming cereus (Cereus grandiflorus) have been used