cuzco 232 CYCLOMETER at 59* 3' W., about 30 miles above the mouth of the river. CUZCO (koz'ka), an inland city of Peru, capital of a department of same name (area, 156,270 square miles; pop. about 500,000), and formerly capital of the eni;pire of the Incas, at the foot of some hills, 11,380 feet above the level of the sea, about 400 miles E. S. E. of Lima. According to tradition, this town was founded in 1043, by Manco Capac, the first Inca of Peru. The grandeur and magnificence of the edifices, of its fortress, and of the Temple of the Sun, struck the Spaniards with astonishment in 1534, when the city was taken by Francis Pizarro. On the hill toward the north are yet seen the ruins of a fortress built by the Incas. Pop. about 15,000. CYANAMID. NC.NH2, formed by the action of ammonia on cyanogen chlo- ride. The name is also applied to the compound calcium, Cyanamid NC.NCa, an important product formed in the fixa- tion of atmospheric niti'ogen by the so- called "cyanamid process." Calcium carbide is first produced by heating car- bon and calcium at high temperatures in an electric furnace, and this compound is then heated under pressure with nitro- gen obtained from the air. The crude product, known also as Nitrolim, is used as a fertilizer and undergoes decomposi- tion in the soil with the production of cyanamid. The latter is then converted to urea, which is hydrolyzed to am- monium carbonate by organisms in the soil (q. V. Nitrogen). CYANIDES, chemical compounds which contain the monad radical (CN)', combined with a metallic element, as K (CN)', potassium cyanide, or with a hydrocarbon radical, as CH2 . (CN) methyl cyanide. Cyanides can be ob- tained synthetically by heating a mix- ture of potassium carbonate and char- coal to redness in a porcelain tube, and passing nitrogen gas through the tube. Also formed when an organic body con- taining nitrogen is heated in a tube with metallic sodium. If cyanides are dis- solved in water rendered alkaline by potash or soda, then a mixture of fer- rous and ferric sulphates is added, and the mixture is rendered acid with dilute hydrochloric acid, a blue color of ferro- cyanide of iron being formed. If the liquid containing a cyanide be made acid with a few drops of hydrochloric acid, and then a little yellow ammonium sul- phide be added, and the liquid gently evaporated till the excess of sulphide is volatilized, the residue will give a red color when a few drops of tincture of iron are added. Cyanides give a curdy white precipitate with silver nitrate, which is insoluble in cold nitric acid, the dry precipitate, Ag(CN)', when heated in a small glass tube, giving off cyano- gen. Cyanides may be formed by dis- solving metallic oxides or hydroxides in a solution of hydrocyanic acid, H . CN, also by double decomposition of metallic salts, with potassium cyanide if the re- sulting cyanide is insoluble. CYANOGEN, dicyanogen, (CN):, or (N— O — (C— N), or Cy.. Obtained by heating silver or mercuric cyanide; also by dry distillation of ammonium oxalate. Cyanogen is a colorless poisonous gas which liquifies at — 25°, or under a pres- sure of four atmospheres at 20°, and at — 34° becomes crystalline. It burns with a peach-blossom-colored flame, forming CO2 and nitrogen; water dissolves four volumes, and alcohol 23 volumes of the gas. Cyanogen is very poisonous, and smells like prussic acid. Cyanogen gas passed into strong aqueous hydrochloric acid is converted into oxamide. Cyan- ogen dissolves in an aqueous solution of potash, forming cyanide and isocyanate of potassium. Cyanogen can be regarded as the nitril of oxalic acid. Dry am- monia gas and cyanogen combine, form- ing hydrazulmin, C4N6H6. Small quan- tities of cyanogen are formed during the distillation of coal. Potassium burns in cyanogen gas, forming potassium cya- nide. Cyanogen was discovered by Gay- Lussac in 1815. CYCLADES (sik'la-dez), the principal group of islands in the Grecian Archi- pelago now belonging to the Kingdom of Greece, so named from lying round the sacred island of Delos in a circle. The largest islands of the group are Andros, Pares, Myconos, Tenos, Naxos, Melos, and Thera or Santorin. They are of volcanic formation and generally moun- tainous. Some are very fertile, produc- ing wine, olive-oil, and silk; others almost sterile. The inhabitants are ex- cellent sailors. Pop. about 130,400. CYCLAMEN, sowbread, a genus of primulacese, family p)Hmulidse. The root of the same species is said to be eatable when dried or roasted. CYCLES. See Bicycle. CYCLOMETER, an invention for measuring and recording the distance traveled by wheeled vehicles, extensively used in cycling. Its most important ap- plication is in railroading. The apparatus is connected with the wheels of a car, and by recording the number of revolu- tions tells on a sheet of paper inside the car the number of miles traveled. It is purely automatic, and in addition,
