are produced. Insoluble cliromates fused with nitre yield soluble yellow potassium chromate, K 2 CrO 4 . This salt is prepared on a large scale by oxidizing chrome-iron ore in a furnace, in the presence of carbonate, sulphate, or chloride of potassium, and chalk or lime. The red bichromate or acid chromate of potassium, K 2 O 2 O 7 , is made by acidifying a solution of the neutral salt, or by Jacquelin s process, an which chrome-iron ore is ignited with chalk to obtain the neutral chromate of calcium ; this is then converted by sulphuric acid into calcium bichromate, which by double decomposition with potassium carbonate yields the potas sium bichromate. It melts at a red heat, and at a white heat evolves oxygen, as also when warmed with sulphuric acid. Heated with sulphur or charcoal it deflagrates. The solution gives with sulphydric acid a precipitate of mixed chromic oxide and sulphur. Ammonium bichromate is decomposed on the application of heat into nitrogen, vater, and chromic oxide. The oxides and salts of chromium give, in both the inner and outer blowpipe flames, a green bead with borax. Chromium unites with iron and aluminium; and can be obtained combined with mercury by treating a solution of a chromic salt with sodium amalgam. Chromium is estimated gravimetrically in the form of the sesquioxide, or of a lead or barium salt ; v-olumetrically, by the oxidizing effect of a chromate
on oxalic acid, hydriodic acid, or potassium ferrocyanide.
The alloy termed chromeisen, containing about three parts by weight of chromium to one of iron, is hard enough to serve for cutting glass. An extremely soft steel can be made by em ploying it instead of spiegeleisen in Siemens s steel process. Chromium compounds are in request for a great diversity of purposes. Free chromic acid and potassium bichromate are used in calico-printing, and in bleaching tallow and palm oil. The bichromate is also employed for the volumetric estimation of ferrous salts, in the printing of photographs, and in galvanic batteries ; it has even been used with lead chromate for the adulteration of snuff. It is itself sometimes adulterated with a mixture of sulphate and chloride of sodium, coloured with a strong solution of bichromate. Potassium bichromate in contact with the skin produces dangerous ulcers, and internally it acts as a violent poison. Fused lead chromate is of value in organic chemistry as an oxidizer, and the unfused salt is the well- known pigment chrome-yelloiv. Chrome-red is a basic lead chromate, Pb 2 CrO 5 . Other pigments are the sesquioxide of chromium, or chrome-green, used in glass-staining, porcelain- painting, and in the printing of bank-notes ; Pannetier s emerald green, a hydrate of the composition H 4 Cr 2 O 5 ; Leune and Castelhaz s green, another hydrate ; Guignet s pigment vert, a basic chromic borate ; and Plessy s green, which is a phosphate of chromium. Casali (Gazzetta Chimica Italiana, 1874) recommends for the preparation of an intense green pigment to calcine an intimate mixture of 1 part of potassium bichromate and 3 parts of baked gypsum ; the mass obtained is boiled with water, or treated with hydrochloric acid. The pigment used to pro duce a pink colour on earthenware is made by heating to redness a mixture of 30 parts of peroxide of tin, 10 of chalk, and 1 of potassium chromate, the product being powdered and washed with hydrochloric acid.
(f. h. b.)
CHRONICLES, Books of. In the Hebrew Canon the Chronicles form a single book, entitled O^Pfn ^lljn, Events of the Times. The full title would be D n nm iDD, Boole of Events of the Times; and this again appears to have been a designation commonly applied to special histories in the more definite Shape Events of the Times of King David, or the like (1 Chron. xxvii. 24 ; Esth. x. 2, &c.). The Greek translators divided the long book into two, and adopted the title HapaXfLTro/jieva, Things omitted _scil. in the other historical books]. Jerome, following the sense of the Hebrew title, suggested the name of Chronicon instead of Paralipomenon primus et secundus. Hence the English Chronicles.
The book of Chronicles begins with Adam and ends abruptly in the middle of Cyrus s decree of restoration. The continuation of the narrative is found in the book of Ezra, which begins by repeating 2 Chron. xxxvi. 22, 23, and filling up the fragment of the decree of Cyrus. A closer examination of those parts of Ezra and Nehemiah which are not extracted word for word from earlier docu ments or original memoirs, leads to the conclusion that Chronicles-Ezra-Nehemiah was originally one work, dis playing throughout the peculiarities of language and thought of a single editor, who, however, cannot be Ezra himself as tradition would have it. Thus the fragmentary close of 2 Chronicles marks the disruption of a previously- existing continuity, due, presumably, to the fact that in the gradual compilation of the Canon the necessity for incorporating in the Holy Writings an account of the establishment of the post-Exile theocracy was felt, before it was thought desirable to supplement Samuel and Kings by adding a second history of the period before the Exile. Hence Chronicles is the last book of the Hebrew Bible, following the book of Ezra-Nehemiah, which properly is nothing else than the sequel of Chronicles.
While the original unity of this series of histories can hardly be questioned, it will be more convenient in the present article to deal with Chronicles alone, reserving the relation of the several books for the article Ezra and Nehemiah. The author used a different class of sources for the history before and after the Exile ; and thus the critical questions affecting the Chronicles are for the most part quite distinct from those which meet us in the book of Ezra. Besides, the identity of authorship in the two histories cannot be conclusively demonstrated except by a comparison of results drawn from a separate consideration of each book.
can be determined by internal evidence. The colour of the language stamps the book as one of the latest in the Old Testament, but leads to no exact determination of date. In 1 Chron. xxix. 7, which refers to the time of David, a sum of money is reckoned by claries [E. V., drams], which certainly implies that the author wrote after this Persian coin had been long current in Judea. But the chief passage appealed to by critics to fix the date is 1 Chron. iii. 19, sqq., where the descendants of Zerubbabel seem to be reckoned to six generations (so Ewald, Bertheau, &c.). The passage is confused, and the Septuagint reads it so as to give as many as eleven generations (so Zunz, Noldeke) ; while on the other hand those who plead for an early date are disposed to assume an interpolation or corruption of the text, or to separate all that follows the name of Jesaiah in ver. 21, from what precedes (Movers, Keil). But it seems impossible by any fair treatment of the text to obtain fewer than six generations, and this result agrees with the probability that Hattush, who, on the interpretation which we prefer, belongs to the fourth gene ration from Zerubbabel, was a contemporary of Ezra (Ezra viii. 2). Thus the Chronicler lived at least two generations after Ezra. With this it accords very well that in Nehemiah five generations of high priests are enumerated from Joshua (xii. 10, sqq.), and that the last name is that of Jaddua, who, as we know from Josephus, was a contem porary of Alexander the Great. That the chronicler wrote after the fall of the Persian monarchy has been argued by Ewald and others from the use of the title King of Persia (1 Chron. xxxvi. 23). What seems to be certain and important for a right estimate of the book is that the
author lived a considerable time after Ezra, and stood