Page:The American Cyclopædia (1879) Volume IV.djvu/568

556 CHRONICLES CHRONOLOGY (chrome alum), which crystallizes by spontane- ous evaporation in bold octahedra, and corre- sponds in form and composition to ordinary alum. The following are the most important applications of chromium compounds in the arts. The yellow or neutral chromate of pot- ash is the basis of all other preparations, be- ing made directly from the chrome ironstone. The red or bichromate of potash is obtained from the foregoing salt, and is extensively em- ployed in the arts. In photography it is the basis of most of the printing processes, on ac- count of its property of rendering gelatine in- soluble by exposure to light. In dyeing, it is extensively used as a mordant. It is the ma- terial from which the chromic oxide, chromic acid, and the metallic chromates are prepared. Chromic oxide is the most insoluble green pig- ment known ; it is extensively used in printing bank notes and in staining glass and painting porcelain. Chromic acid is a powerful oxidizing agent, and is used on this account in chemical re- searches ; is found very valuable as an exciting fluid in galvanic batteries; was used for prepar- ing the beautiful mauve red from aniline ; is em- ployed in bleaching palm oil, and in destroying the empyreumatic impurities of acetic acid, &c. The chromates of lead, bismuth, baryta, stron- tia, and zinc are employed as pigments, vary- ing in tint from the vermilion red of the basic chromate of lead to the pale straw yellow of the strontia salt. The common chrome green is a mixture of chromate of lead and Prussian blue. The beautiful violet chromic chloride has been proposed as a remedy for cancer. Chromium steel, made by combining about 5 per cent, of chromium with cast iron, possesses most remarkable properties. On account of its excessive hardness, it is the best metal for the construction of safes, while its tensile strength, equal to a strain of 140,000 Ibs. to the square inch, especially adapts it to the construc- tion of suspension bridges. CHRONICLES, the name first given by Jerome to two books of the Old Testament, which in the English Bible are the last of the historical books, while in the Hebrew Scripture they conclude the entire volume. By the Alexan- drine translators they were termed Paralei- pomena, or things omitted, being regarded as supplementary to the previous histories. In the original Hebrew they are entitled "Words of the Days" (Dibre hayamim), and form, as their internal character demonstrates, but one book. The Chronicles open with gen- ealogical registers of ancient and renowned families or races ; they then narrate the his- tory of David, harmonizing with the earlier account in the book of Samuel ; then follows a history of Solomon, and of the increasing prosperity and glory of the Jews under him ; after the division of the kingdom at his death, they trace the history of Judah, the more powerful branch, and continue the nar- rative till after the fall of Israel, and to the end of the exile in Babylon. They thus had a com- paratively late origin, which is indicated also by the style and idiom, and by the Levitical coloring which overspreads much of the narra- tive. The Jewish and Christian traditions, from the earliest times down to the 17th cen- tury, have referred the Chronicles to the age and to the pen of Ezra. Spinoza assigned their origin to the time of the Maccabees, and his opinion has been accepted by several later scholars. Bertheau, one of the ablest writers on this book, believes it was written about 300 B. C. The earlier Jewish records furnished the materials of the history in the Chronicles, and numerous books are mentioned as sources and authorities which are not extant, or have not been admitted into the canon. The chief source appears to have been a "Book of the Kings of Judah and Israel," which however cannot have been our canonical book of Kings. The design of the book seems to have been, by a review of the history of the theocracy, to prove that Levitical worship had been maintained and favored by all pious kings, and that adhe- rence to it or departure from it had been the condition of fortune or misfortune to the Jew- ish people. The discrepancies between the books of Chronicles and of Kings have occasioned an important discussion on the trustworthiness of the history of the former. Prominent among those who have denied to the accounts pecu- liar to the book of Chronicles any claim to credibility are De Wette, Beitrage eur Einlei- tung ins Alte Testament (1806), and Gram- berg, Die Chronik nach ihren geschichtlichen Character und ihrer Glaubwurdigkeit neu ge- pruft (1828). Among the most successful writers in vindication of the Chronicles are Movers (Kritische Untersuchungen uber die Bi- blische Chronik, Berlin, 1833) and Keil (Apolo- getischer Versuch uber die Chronik (Berlin, 1883). Of more recent commentaries, the most valuable is that of Bertheau, Die Bucher der Chronik erkldrt (Leipsic, 1854; 2d ed., 1860; English, Edinburgh, 1857). See also the intro- ductions to the Old Testament by Havernick, Davidson, and Bleek, and Ewald's Geschichte des Volkes Israel. CHRONOLOGY (Gr. ^povoAoyfa, from xp^of, time, and A<5yof, discourse), the science of estab- lishing historical dates, by arranging events in the order of their succession, and determin- ing the interval between each and some fixed period in time. We are so accustomed to the facility with which this is accomplished by means of the Gregorian calendar and the con- ventional fixed point of the Christian era, that we can hardly appreciate the obstacles which have been overcome in order to bring the sci- ence to its present state. It was necessary at the outset to find some tangible standard by which to measure the intangible element of time. The most obvious measure is the day, or regular interval between one apparent ris- ing or setting of the sun and another. This, though exact as far as we can know, is so short as to be inconvenient when applied to