Page:The American Cyclopædia (1879) Volume III.djvu/544

538 CADMIUM OADOUDAL tained by dissolving the regulus in sulphuric acid, and converting it into a sulphide, by means of sulphuretted hydrogen ; then redis- solving and reprecipitating by carbonate of ammonia, and reducing with a proper flux. As thus obtained, it is a white, soft, malleable, ductile metal. It leaves a mark upon paper the same as lead, and when bent gives out a creaking sound similar to that known as the "tin cry." It can be distilled the same as zinc ; but unlike zinc, when it is set on fire and burns, it gives a brown oxide. It some- times happens that zinc white is contaminated by this brown powder and rendered worthless as a paint. Cadmium has a specific gravity of 8-6 ; fuses at 315 0. (60'0 F.) ; and boils at 860 C. (1,580 F.). Specific gravity of its gas, 3'9, or 56 times heavier than hydrogen. When alloyed with other metals, cadmium causes them to fuse at a lower temperature ; a very little of it renders copper perfectly brittle. A composition of 78 parts of cadmium and 22 of mercury was for a long time used for plugging teeth ; but, as the amalgam oxidizes easily and turns yellow, and the mercury proves injurious to health, this application is nearly abandoned. Mr. Abel has proposed an alloy for jewellers' use, which is said to be very malleable and ductile, and to possess a fine color. It is com- posed of 750 parts of gold, 166 of silver, and 84 of cadmium. Wood's alloy, which fuses at 158 F., is composed of 2 parts of cadmium, 2 of tin, 4 of lead, and 8 of bismuth. It is as a yellow paint that cadmium compounds are most highly prized. By mixing a solution of gum arabic, chloride of cadmium, and hypo- sulphite of soda together, we obtain a fine yel- low paint, which is one of the most durable known to artists. There are other modes of making it, and the purity of color depends very much upon the absence of metals that turn black when mixed with sulphur, and upon the care with which it is dried. The very property that led to the condemnation of zinc white, and which ultimately brought about the discovery of cadmium, is the yellow color, now most frequently turned to valuable account. The keeping properties of the collo- dion, made sensitive by the iodide and bromide of cadmium, have made these salts great fa- vorites with photographers, and a new use for cadmium has sprung up of late years in this direction. Manufacturers are becoming accus- tomed to save the furnace and flue dust of zinc works, and separate the cadmium from them, and in this way the supply of the metal is increasing. The following mixture burns with a brilliant white flame, surrounded by a magnificent blue border : saltpetre, 20 parts ; sulphur, 5 ; sulphide of cadmium, 4 ; lamp- black, 1. This can be moistened, and made up into halls or candles, and ignited after the manner of a fuse. The salts of cadmium are in general soluble and take crystallized forms. They have no color, but possess a nauseous taste and act as emetics. The sulphate is ob- tained by dissolving the carbonate or the metal itself in dilute sulphuric acid, a little nitric acid being added. It is a salt of similar properties to those of sulphate of zinc, but much more powerful. It is used in medicine in the treat- ment of syphilis, rheumatism, and gout ; in dis- eases of the eyes as an astringent and stimu- lant, and for the removal of specks and opaci- ties of the cornea. There seems to be still some doubt as to the proper dose for internal use, since some authorities state that it is about equal in power to sulphate of zinc, while others estimate it as being ten times more active. ADMCS, a mythical king of Thebes, son of Agenor, king of Phoenicia, and brother of Eu- ropa, who is said to have introduced into Hellas the 16 simple letters of the Greek alphabet. He left his native country in search of his sister Europa, who had been borne off by Jupiter. On making inquiry of the Delphic oracle as to what state he should choose for settlement, he was advised to follow a heifer which would meet him. Cadmus found her in Phocis tod followed her into Bceotia, where she sank down on a spot which Cadmus called Cadmea, and which became the citadel of Thebes. He sent some of his company to draw water from a well sacred to Mars. This well was guarded by a dragon, which slew the intruders. Cad- mus slew the dragon, and was directed by Minerva to sow the monster's teeth. He did so, and a host of armed men immediately sprang from the ground, who were called the Sparti, or the Sown. These were about to turn upon Cadmus, but the latter threw a stone amid them, and a fight ensued which did not cease until all were slain except five. These survivors became tractable and helped Cadmus to build a new city. Cadmus was hon- ored as the founder and patron of Thebes. To recompense him for his perils the gods gave him Harmonia, the daughter of Mars and Ve- nus, for a wife, and honored their nuptials with their presence and with gifts. Cadmus subse- quently became king of the Enehelians, fought the Illyrians, and had a son called Illyrius ; and finally he and Harmonia were changed into serpents and removed to Elysium. CADOUDAL, Georges, the leader of the Chouans or Breton insurgents in the French revolution, born at Kerleano, in lower Brittany, Jan. 1, 1771, guillotined in Paris, June 25, 1804. He was educated at the college of Vannes, and at first shared in the reformatory hopes which the revolution inspired ; but the attempts of the assembly against the church set him in op- position to all the new ideas. With 50 of his compatriots he joined in 1793 the Vendean chiefs at Fougeres. He was soon arrested and thrown into prison, but escaped in the disguise of a sailor, and became formidable at the head of an army of Chounns. After the disaster of Quiberon, he united the remains of the royal- ist troops, but was unable to make progress against the republican army under Hoche. By his efforts the insurrection was renewed iu