CHLORITE CHOLERA. 



203 



gen ; and it has been found useful, among such per- 

 sons as are obliged to frequent places where conta- 

 gious effluvia are constantly developed, to bathe the 

 hands and arms with its solution. Chlorine, united 

 with hydrogen, forms an important compound, called 

 muriatic, or hydrochloric acid gas. (See Muriatic 

 Acid). With oxygen, it gives rise to four distinct 

 compounds, which are remarkable for the feeble at- 

 traction of their constituent elements, notwithstand- 

 ing the strong affinity of oxygen and chlorine for 

 most elementary substances. These compounds are 

 never met with in nature. Indeed, they cannot be 

 formed by the direct combination of their constitu- 

 ents; and their decomposition is effected by the 

 slightest causes. Notwithstanding this, their union 

 is always regulated by the law of definite proportions, 

 as appears from the following tabular view, illustra- 

 tive of their composition. 



Chlorine. Oxygen, 



Protoxide of chlorine 

 Peroxide of chlorine 

 Chloric acid 

 Perchloric acid 



Chlorine forms, along with nitrogen, one of the 

 most explosive compounds yet known, and was the 

 muse of serious accidents to M. Dulong, its discov- 

 erer, and afterwards to Sir H. Davy. The chloride 

 of nitrogen is formed from the action of chlorine on 

 some salt of ammonia, chlorine and nitrogen being 

 incapable of uniting, when presented to each other 

 in their gaseous form. Its formation is owing to the 

 decomposition of ammonia (a compound of hydrogen 

 and nitrogen) by chlorine. The hydrogen .of the 

 ammonia unites with chlorine, and forms muriatic 

 acid ; while the nitrogen of the ammonia, being pre- 

 sented in its nascent state to chlorine, dissolved in 

 the solution, enters into combination with it. The 

 chloride of nitrogen has a specific gravity of 1-653; 

 it does not congeal by the intense cold produced by 

 a mixture of snow and salt. At a temperature be- 

 tween 200 and 212 it explodes ; and mere contact 

 with most substances of a combustible nature causes 

 detonation at common temperatures. The products 

 of the explosion are chlorine and nitrogen. Three 

 distinct compounds of chlorine and carbon have of 

 late been made known by Faraday ; but for an ac- 

 count of these, as well as of the chlorides of sulphur 

 and of phosphorus, and the chloro-carbonic acid gas, 

 the reader is referred to the larger treatises on che- 

 mistry, it being incompatible with the plan of the pre- 

 sent work to enter into those details which are not 

 connected with the useful arts, or which are not ab- 

 solutely necessary in order to afford a correct idea of 

 the mode of reasoning and general theory of the sci- 

 ence.* 



CHLORITE. See Talc. 



CHOC (from the French choc, the violent meeting 

 of two bodies), in military language, signifies a vio- 

 lent attack. It is generally applied to a charge of 

 cavalry. To give such an attack its full effect, it is 

 necessary, 1. that the line be preserved unbroken, so 

 that the attack shall take effect at all points at the 

 same tune ; 2. that the horses be strong and heavy, 

 that their momentum may be great; 3. that the 

 charge be made as swiftly as possible, not merely for 



* A letter of M. Dauvergne to M. Oay-Lttssac, in the 

 Ann de C'himie, recently published, states the effect of 

 chlorine as an antidote of hydrocyanic acid. A cat, to which 

 two drops of hydrocyanic acid were given through the lach- 

 rymal gland, was affected most violently by the poison. 

 While the animal wan in this condition, some chlorine was 

 put into her mouth, and, one hour after, she was able to 

 make a few -tottering steps : the next morning the animal 

 was quite well. It has alxo been lately stated, in the pub. 

 lie journals, that the French physicians have found chlorine 

 very effectual in preserving from the plague, if put on the 

 linen, Her,. 



the sake of the physical effect, but also of the moral 

 effect which it has on the enemy. This swiftness, 

 however, must be attained gradually, increasing as 

 the distance diminishes. The charge commences 

 with a short trot ; a long trot follows ; at the dis- 

 tance of 150 paces, this is increased to a gallop ; and 

 50 paces from the enemy, the horse must be put to 

 his speed. A choc, whether successful or not, is of 

 short duration. 



CHOCOLATE. See Cacao. 



CHOCTAWS, or FLAT-HEADS; a tribe of In- 

 dians, residing between the Mississippi and the 

 Tombigbee, partly in Alabama, but mostly in Mis- 

 sissipi. Their territory is bounded N. and N. E. by 

 that of the Chickasaws. The country has a fertile 

 soil, and is traversed by the upper waters of the 

 Yazoo, Big Black, and Pearl rivers. Their number 

 is estimated at about 20,000 or 25,000. They are a 

 hardy, intrepid, and ingenious race, and have made, 

 within the last twenty years, great advances in agri- 

 culture and other arts of civilized life. They raise 

 cotton, and manufacture it into cloth for their ordi- 

 nary use, and often appear well clad in garments of 

 their own making. In 1818, the American board of 

 foreign missions established a mission among the In- 

 dians at Elliot, on the Yalo Busha, a branch of the 

 Yazoo ; and, since that period, eight other similar 

 establishments have been formed. See Indians. 



CHOCZIM (Chotschim) ; an important frontier 

 fortress of Russia, on the right bank of the Dniester, 

 opposite to Kaminiec, in Bessarabia, with 25,000 in- 

 habitants and a considerable trade. The people are 

 entirely employed in furnishing supplies for the army. 

 The Turks caused Choczim to be regularly fortified, 

 in 1718, by French engineers ; but it was taken by 

 the Russians in 1730, 1769, and 1788. As the Pruth, 

 in Europe, is, at present, the boundary of the two 

 empires, the situation of Choczim renders it of great 

 importance as an arsenal and place of rendezvous. 



CHODOWIECKI, DANIEL NICHOLAS, a painter 

 and engraver, was born at Dantzic, 1726, and received 

 from his father, in his leisure hours, his first instruc- 

 tion in miniature painting, which he practised with 

 great assiduity, in order to support his mother, after 

 the death of his father. His first trials excited the 

 astonishment of connoisseurs. A little engraving, 

 the Play at Dice, in 1756, particularly attracted the 

 attention of the academy of Berlin. During the 

 seven years' war, he engraved various subjects con- 

 nected with it ; among others, the Russian Prisoners 

 at Berlin, which is now rare. The history of the un- 

 happy Calas gave him an affecting subject for a pic- 

 ture, which, at the desire of all who saw it, he en- 

 graved on copper. The impressions of the year 1767 

 are particularly esteemed. Almost all the plates to 

 Lavater's Physiognomical Fragments are from his 

 designs. He engraved several of them himself. At 

 last, scarcely a book appeared in Prussia, for which 

 he did not engrave at least a vignette. The number 

 of his engravings is more than 3000 ; but we must 

 observe, that he was in the habit of making changes 

 in his plates, after a number of copies had been struck 

 off, so that all the copies of the same plate are not 

 entirely alike. He must be considered the founder 

 of a new art in Germany that of representing mo- 

 dern figures. He died, Feb. 1, 1801, at Berlin, 

 where he was director of the academy of arts. He 

 was universally esteemed for his integrity. 



CHOIR ; that part of the church where the cho- 

 risters sing. In some old churches, the seats of the 

 choristers, and other parts of the choir, are orna- 

 mented with admirable carved work. See Architec- 

 ture, vol. I, page 343, sect, vii., Gothic style. 



CHOLERA (Celsus derives it from xi and fin, 

 literally, a flow of bile, and Trallian from ^o*. and 



