CHROME- CHRONICLE. 



225 



The word chromatic has been adopted, as it is be- 

 lieved, because the Greeks were in the habit of desig- 

 nating this genus by characters of various colours, or, 

 as some say, because the chromatic genus is a mean 

 between the other two, as colour is a mean between 

 white and black (this seems to be a very poor explana- 

 tion) ; or, lastly, because the chromatic genus, by its 

 semitones, varies and embellishes the diatonic, thus 

 producing an effect similar to that of colouring. In 

 modern music, the word chromatic simply means 

 a succession of semitones, ascending or descending. 

 Thus the expressions chromatic semitone (the interval 

 which is found between any given note and that 

 same note raised by a sharp or lowered by a flat), 

 chromatic tcale, chromatic modulation, are terms in 

 use. 



CHROME ; the name of a metal, which, combin- 

 ed with oxygen so as to be in the state of an acid, 

 was discovered by Vauquelin, in an ore of lead from 

 Siberia. This metal has since been found combined 

 with iron in America, and at Unst, one of the Shet- 

 land isles. It appears also to be the colouring prin- 

 ciple of the emerald and the ruby, and has received 

 its name from its property of assuming brilliant colours 

 in the combinations into which it enters. Chrome, 

 which has hitherto been procured in very small quan- 

 tities, owing to its powerful attraction for oxygen, 

 may be obtained by mixing the oxide of chrome with 

 charcoal, and exposing the mixture to the most in- 

 tense heat of a smith's forge. It is brittle, of a gray- 

 ish-white colour, and very infusible. Its specific gra- 

 vity is 5*9. Clirome unites with oxygen in three 

 proportions, forming two oxides and one acid. The 

 protoxide is of a green colour, exceedingly infusible 

 by itself, but with borax, or vitreous substances, it 

 melts, and communicates to them a beautiful emerald- 

 green colour. The protoxide is employed at the manu- 

 factory of Sevres, in France, to give a fine deep- 

 green to the enamel of porcelain. It is applied 

 without a flux, and melted with the enamel. Chro- 

 mic acid, however, is the most important of the 

 compounds formed by this metal along with oxygen. 

 It is usually prepared for chemical purposes by mix- 

 ing solutions of nitrate of barytes and chromate of 

 potash, and digesting the chromate of barytes that is 

 formed in dilute sulphuric acid. This abstracts the 

 barytes, and the chromic acid is procured, by eva- 

 poration, in crystals of a fine ruby-red colour. It is 

 very soluble in water, has a sour, metallic taste, and 

 all the characters of & strong acid. It combines 

 with the alkalies, earths and metallic oxides, forming 

 salts, many of which have very rich colours. The 

 alkaline chromates are soluble and crystallizable. 

 They are of a yellow or red colour, the neutral 

 chromates being commonly yellow, and the bi-chro- 

 mates, red or deep orange. The best known of 

 these is the bi-chromate of potash, which is one of 

 the most splendid, and, at the same time, one of the 

 most useful salts. The manner in which it is form- 

 ed is as follows : Cliromate of iron, or rather fer- 

 ruginous oxide of chrome, reduced to fine powder, is 

 mixed with lialf its weight of nitrate of potash, and 

 heated strongly for an hour or two in crucibles. The 

 resulting masses are then repeatedly digested with 

 water, and the coloured liquids, which are slightly 

 alkaline, saturated with nitric acid, and concentrated 

 by evaporation, till no more crystals of nitre can be 

 obtained from them. The yellow liquid, being now 

 set aside for a week or two, deposits a copious crop 

 of crystals, whose form is that of a four-sided prism, 

 terminated by dihedral summits. Their colour is an 

 intense lemon-yellow, with a slight shade of orange, 

 100 parts of water at 00 dissolves about forty-eight 

 parts ; but boiling water dissolves almost any quan- 

 tity. Its solution in water decomposes most of the 

 ii. 



metallic salts ; those of mercury, of a fine red ; cop- 

 per and iron, of a reddish brown ; silver, dairk red, 

 and lead, of a beautiful yellow colour, now mufch used 

 as a pigment, under the name of chrome yellow. 

 Chrome yellow is largely manufactured in the United 

 States, at Baltimore, near which place is found one 

 of the most remarkable deposits of ferruginous oxide 

 of chrome in the world. The process consists in 

 adding a solution of acetate of lead (or sugar of lead) 

 to the rough solution of chromate of potash, from 

 which the nitrate of potash has been just separated 

 by crystallization. The acetate of lead is added as 

 long as any sediment falls. The liquid is then filter- 

 ed, and the yellow precipitate left on the filters, 

 dried for sale. 



CHROMIC ACID. See Chrome. 



CHRONIC (from xfoes, time) ; a term applied to 

 diseases which are of long duration, and mostly with- 

 out fever. It is used in opposition to the term acute, 

 which is applied both to a pungent pain, and to a 

 disease which is attended with violent symptoms, 

 terminates in a few days, and is attended with dan- 

 ger. On the other hand, a chronic disease is slow in 

 its progress, and not so generally dangerous. 



CHRONICLE, strictly speaking, is a history di. 

 gested according to the order of time. In this sense, 

 it differs but little from annals. The term is mostly 

 used in reference to the old histories of nations, writ- 

 ten when they were comparatively rude. Chronicles 

 belong to the sources of history, and many have been 

 handed down from early ages ; for instance, the two 

 books of the Chronicles of the Hebrews, which be- 

 long to the Old Testament. With many nations, 

 such chronicles were written under the authority of 

 government ; and priests, being the only men of learn- 

 ing among uncultivated tribes, were intrusted with 

 this office. In the early Christian ages, also, clergy- 

 men were generally the authors of the chronicles ;*' 

 e. g., Eusebius, bishop of Caesarea, collected from 

 other historical works his Chronicle of ancient his- 

 tory. Hieronymus of Stridon translated it into Latin, 

 in the fourth century, and others continued it. Many 

 historical works of the Byzantines (q. v.) are also 

 chronicles. We might mention, likewise, the Alex- 

 andrine chronicle ( Chronicon paschale), published by 

 Du Fresne ; also the chronicles written by monks, 

 particularly by the diligent Benedictines, in the mid- 

 dle ages, some of which embraced the whole history 

 of the world, from its beginning to their own time 

 (as the Chronicle of Rhegino, of Otto of Freisingen, 

 &c.) ; others, the history of a certain period (as Luit- 

 prand's History of his Time, from 891 to 946), or of a 

 single nation ( as the History of the Franks, by Gre 

 gory of Tours ; that of the Lombards, by Paulus 

 Diaconus ; the English Chronicles, by Stow, &c.), or 

 the history of single provinces, cities, and institutions 

 (as the Chronicle of the Abbey of St Denis ; the 

 Chronicle of Cologne) ; also the history of individuals 

 (as Eginhard's History of Charlemagne), and of single 

 events. They have been published partly in large 

 collections (for instance, Scriptores Rerum Germani- 

 carum), and, until the 13th and 14th centuries, were 

 mostly written in Latin. Of many of them the au- 

 thors are not known. In this case, they are called 

 after the place where they were written or where 

 they were found. 



These chronicles bear the impression of their time, 

 displaying the ignorance and credulity of their 

 authors, find abounding in religious and moral reflec- 

 tions. We must admit, in their favour, however, that 

 they are not filled with political disquisitions and su- 

 perficial reasoning, of which modern histories afford 

 so many instances. The chronicles of the middle 

 ages were not written with the purpose of support- 

 ing certain principles, but generally give simple facts ; 



