CASSIOPEIA, in astronomy, a con stellation of the northern hemisphere, si tuated opposite to the Great Bear, on the other side of the pole. See Asvnoxowr.
In the year 1572, a remarkable new star appeared in this constellation, surpassing Sirius or Lyra in brightness and magni tude. It appeared even bigger than Ju piter, which, at that time, was near his perigee, and by some was thought equal to Venus, when she is in her greatest lus tre ; but in a month it began to diminish in lustre, and in about eighteen months entirely disappeared.
It alarmed all the astronomers of that age, many of whom wrote dissertations on it ; among the rest, Tycho Brahe, Kep ler, Maurolycus, Lycetus, Gramineus, &c. Beza, the Landgrave of Hesse, Rosa, Sm. wrote to prove it a comet, and the same which appeared to the Magi at the birth of Jesus Christ, and that it came to declare his second coming : they were answered on this subject by Tycho. Se veral astronomers are of opinion,that this star has a periodical return, which Keill and others have conjectured to happen every 150 years. Mr. Pigott adopts the same opinion ; and he accounts for its not being noticed at the completion of every term, by its variable lustre at different periods, so that it may sometimes increase only to the ninth magnitude ; and if this be the case, its period is probably much shorter.
CASSiUS, precipitate of, obtained from the muriate of gold by the means of tin. It is highly valued for the beauty of the colour which it gives to glass or enamel. It may be obtained by simply immersing a plate of tin in a dilute solution of muri ate of gold : but the usual mode is to dis solve pure gold in a nitro-muriatic acid, composed of three parts of nitric acid and one of the muriatic. The tin is prepared by dissolving it, without heat, in an acid composed of two parts of nitric and one of muriatic acid, previously diluted with an equal weight of water. This solution being saturated, is diluted with one hun dred parts of water, to which the solution of gold, in quantity equal to half the quan tity of solution of tin, is added : the liquor becomes of a beautiful purplish red co lour, and a precipitate subsides, which is to be washed and dried. This is the only preparation capable of giving a red co lour to glass, which then serves as an imitation of the ruby.