Page:The New International Encyclopædia 1st ed. v. 04.djvu/813

CHROMIUM. 715 CHRONICLES. itself has no important uses, although when added in quantities of less than 1 per cent, to »teel it yields an alloy called chroiniuni sled, which has a fine texture, great hardness, tenacity, and elasticity. An alloy of chromium with alu- minum has also Ikh'U described. With oxygen chromium forms two basic oxides, which yield, res|>ectively, chromous and chromic compounds, and an acid-foming oxide which yields chro- niates. Chromic oxide nujy be obtained by ignit- ing the hj-droxide or by heating a mixture of potassium bichromate and sulphur. It is a green pigment of great ])ermanence that is known in commerce as chronn' grccu and ultramarine green. The hydrated oxide, which is made by heating to dull" redness 3 parts of boric acid and 1 part of potassium bichromate, is the pigment known as etncrald green. Guignet's green, I'en- iittticr's green, and Veridian. Of similar com- position is the green pigment called Arnaudon's green. Many of the ehroniates have considerable com- mercial value, especially those of potassium, so- dium, and ammonium. Among the bichromates, that of potassium is the most important, as it is used in the preparation of all other chromium salts. Potassium bichromate is prepared from chromite, the ore being, for this purpose, roasted, finely ground, and mixed with half its weight of potassium carbonate and twice its weight of lime; the mixture is heated to bright redness with an oxidizing flame in a reverberatory furnace, and, on cooling, the resulting mass is treated with hot water; to the solution thus obtained potas- sium sulphate is added for the purpose of precip- itating the lime as sulphate, while the potassiuia chromate produced remains dissolved; finally, dilute sulphuric acid is added in order to con- vert the chromate into bichromate. Potassium bichromate crystallizes in the form of bright-red prisms. It is used for the preparation of chrome pigments for the production of various colors in calico-printing and dyeing: in the manu- facture of safety matches; as a bleaching agent tor tallow, palm oil, etc.. with sulphuric acid : for the oxidation of anthracene to alizarin; in tanning leather; and in consequence of its prop- erty of rendering gelatin insoluble when mixed with that substance and exposed to light, it finds extensive application in photogelatin processes. Lead ehromate is the bright-yellow precipitate obtained when a solution of a lead salt is added to potassium bichromate ; it is used as a pigment under the name of ehromr yellow. CHKO'MOLITH'OGRAPH. See Lithogba.- THY. CHROTJOPLAST (from xP"*«i, c*™""', color -+- xXoctAs, jihislos, formed, from irXiaattv, plas- sein. to form)- A protoplasmic body in plants which contains a pigment other than green, chiefly yellow or red. It is abundant in fruits and flower- leaves. In shape the chromoplasts are rounded, fusiform, angular, or irregular, their form being often determined by the pig- ment they contain. Sometimes the pigment exists in minute droplets in the protoplasm, but more frequently it is crystalline; or both forms may be present together. The crystals vary from needle-like or rod-like to tabular. The blender crystals are sometimes curved and often occur in fascicles. Chromoplasts are de- rived from similar bodies by division. A plas- tid (q.v.), the primary iinditferentiated body. Vol. IV.— »6. may develop directly into a chromoplast, or it may be for a time a leucoplast (q.v.), or a chloroplast (q.v.), and only later produce the red or yellow pigment that characterizes a chromoplast. If the chromoplasts have any spe- cial function it is not known. In a general way the color they impart may be useful, but the color is frequently due to other causes. See Cell; Color ix Plants. CHRO'MOSOME (from Gk. XP"I^, ehruma, color -f- ffuua, suiiia, body). The name given to the loops or other aggregations of chromatin which collect in indirect cell-division about the axis of the spindle and split into halves. The two halves move toward opposite poles of the spindle, where they aggregate and unite into the form of the chromatin of a new nucleus. See CiiKOM.TiN: Cell; Embryoloi;v. CHRO'MOTYPE, or CHRO'MATYPE (from Gk. xP"!"'; ehrOma, color -- riiros, typos, type). A photographic process dependent upon the sen- sitiveness to light of certain chromium salts, especially the bichromates of the alkalies. The chromotype has been superseded by the photo- gelatin processes, and is at present hardly ever used. (See Autotype.) The name is also ap- plied to colored prints produced by 'chromatic printing.' CHRONICLE (from chronic, Fr. chroniqiie. It. crohico, Lat. ehronicus, from Gk. xpowsis, chronikos, relating to time, from xP^*™', ehronos. time). A species of historical record in which events are treated in the order of time. A chronicle is understood to difl'er from annals in being more connected and full, the latter merely recording individual occurrences under the suc- cessive years or other dates. A great many of the older histories were called chronicles, such as the Saxon Chronicle, Holinshed's Chronicle. CHRONICLE OF PA'ROS. An inscription discovered on the island of Paros in 1G27, con- taining memoranda of much historic interest. It mentions various facts, especially the artistic ones, in Greek history, from the legendary reign of Cecrops, King of Athens, in B.C. 1.5S2. The list originally extended to the archonship of Dio- genetus, in B.C. 264 ; but the conclusion, from the year B.C. 35.5. is now lost. As a political and military history the chronicle is faulty. It is preserved at Oxford, among the Arundel marbles. CHRONICLE OF THE KINGS OF ENG- LAND, FROM THE Time of the Rom.xs' Gov- ERX.MEXT LXTO THE DEATH OF KlXG -I.VMES. An historical work by Sir Richard Baker, published in 1613, dedicated to Charles. Prince of Wales, containing a laudatory preface by Sir Henry Wolton (q.v.). It was a very popular work for the century after its publication. It van tlirough seven editions before the close of 16S4. and was translated into Dutch in 1640. In 1730 it was extended up to the reign of George II. It is, however, full of inaccuracies, and was sharply criticised in 1672 by Thomas Bloimt. in a pam- phlet published in Oxford. It was a favorite with Ad<li~on'* Sir P.ogpr de Coverley. CHRONICLES (Heb. DIrrai hay-yamUn, events of the days, Gk. napaetir6tuva. Paralci- pomena. omitted, sc. ptpla. hihlia, books). The name of two of the books of the Old Testament, which in the Hebrew canon form but one book.