757 



CHAPTER-HOUSE. 



CHARIOT. 



dral and conventual churches are buildings for the meeting of the 

 chapter, called chapter-houses. The buildings of this kind connected 

 with Westminster Abbey and York Minster, are octagonal and of 

 singular beauty. [CHURCH.] 



The members of the College of Arms, that is, the heralds and pur- 

 suivants, are said to hold a chapter when they sit together to confer on 

 the business of their office. 



CHAPTER-HOUSE. [CHURCH.] 



CHARACTERISTIC (of a logarithm). The whole number, positive 

 or negative, which precedes the decimal point of a logarithm. The 

 reason of this number having a separate name is, that in Brigg's system 

 it is so easily found as not to form a part of the tables. [LOGARITHM.] 

 In truth, it ought to be called the characteristic of the primitive 

 number of the logarithm; and the following theorem should be an- 

 nounced, The characteristic of a number is the integer portion of its 

 logarithm. 



CHARADE, a species of riddle, in which a word consisting of several 

 syllables is indicated, first by an enigmatical description of each 

 syllable, taken separately, and then by a similar description of the 

 whole. It does not seem to be necessary that the word should consist 

 only of two syllables, according to the definition given in most of our 

 English dictionaries and cyclopaedias. To have anything of wit or 

 ]x)int, a charade should be so contrived, that the ideas employed to 

 denote or suggest the several syllables, and the entire word, shall be all 

 in some way connected together, or arise naturally the one out of the 

 other. This however is often neglected. The following, which we 

 find in the late editions of the dictionary of the French Academy, is 

 not a bad example of a true charade : " My first makes use of my second 

 to eat my whole;" the translation being the word tliiendent (dog's 

 grass). The word charade is said to be derived from the name of the 

 inventor of this particular species of enigma. Some of the best speci- 

 mens of this kind of exercise of ingenuity were written in verse by the 

 late Winthrop Mackworth Praed, and appeared originally in Knight's 

 ' Quarterly Magazine,' where they were called enigmas. The term 

 appears to be originally French, and not to have come into use till 

 towards the end of the last century. 



CHARCOAL is the impure carbon obtained by the decomposition 

 of vegetable matter by heat without free access of air ; during this 

 operation the more volatile elements of the woody fibre are expelled as 

 new compounds, while the carbon the fixed ingredient, remains, mixed 

 however with some saline matter, presently to be noticed, which 

 render* it impure. 



What occurs during the preparation of charcoal will be readily 

 understood by referring to the analysis of woody fibre by MM. Gay 

 Lussac and Thdnard, who found, whatever be the kind of wood 

 employed, that after drying at 212 Fahr. it yielded upon an average 



Carbon 52 



Hydrogen 5-3 



Oxygen 427 



100-0 



Now as the oxygen and hydrogen are almost exactly in the propor- 

 tion!) required to form water, it would appear that if these only could 

 be expelled by heat, the products of the decomposition would be 

 carbon and water. We shall, however, presently mention, that owing 

 to the combination of a part of the carbon with these elements, and 

 also of the oxygen of the air, the compounds which arise from the 

 decomposition of wood are much more complicated, and are of very 

 great importance. 



The making of charcoal for domestic uses, and probably also for such 

 manufacturing or metallurgic processes as the ancients were acquainted 

 with, is of high antiquity. Pliny (lib. 16, c. 6) mentions that the 

 wood was formed into a pile, the top of which was covered with clay ; 

 evidently to prevent the access of too much air, by which, as expe- 

 rience had no doubt taught, it was found that the wood was converted 



: rely into ashes. 



i coal is now prepared by two different methods : one, resembling 

 in principle that just mentioned, consists in piling the wood in a heap, 

 which is covered with turfs and sand to allow of the entrance of such 

 a pdrtion only of atmospheric air as is sufficient to carry on the imper- 

 fect combustion required. The heap is fired at several holes left near 

 the bottom, and a draught of air is obtained by at first leaving an 

 orifice at the top of the heap ; this is afterwards covered, and when it 

 is found that the flame has pervaded the heap entirely, the bottom 

 are also closed. When the mass has cooled, the charcoal remains. 



Within a comparatively few years another method of obtaining 

 charcoal has been adopted, by which the article obtained is said to be 

 better adapted for the purpose of making gunpowder. This is done 

 liy putting the wood into iron cylinders, which are set in brickwork 

 and surrounded by fire ; the wood in the cylinders has no communica- 

 -.nth the external air, and they have only a small opening to allow 

 of the escape of the gaseous products arising from the decomposition of 

 the wood, and the new compounds derived from the combination of its 

 oxygen and hydrogen with a portion of the carbon. 



These products, or at least those which arc condensible, are chiefly 

 water, tar, impure acetic acid, usually called pyioligneous acid [Ac'ETic 

 Ann), creoot [CBEOSOTz], pyroxylic spirit [PYROXYIIC SPIRIT], and 



empyreumatic oil. One hundred parts of oak wood dried in the air 

 yielded 43 of pyroligneous acid, about 4'5 parts of carbonate of potash, 

 M-06 parts of empyreumatic oil, and 2C'2 of carbon; different woods 

 yielded somewhat varying proportions of these substances, but the oak 

 ;ave the largest quantity of charcoal. 



Although the charcoal thus procured is preferable for making gun- 

 powder, yet it is stated that it is not so well liked for many other 

 purposes ; it is also said to be much lighter than that made in the 

 usual way, and this appears to occasion some variation in the degree 

 of heat required for its consumption in a given time, and thus 

 influences many operations. The densest charcoal gives the most heat 

 while burning. 



The general properties of charcoal are, that it is black, sonorous, and 

 brittle, and retains the form of the wood from which it is obtained ; 

 it is insoluble in water ; infusible and fixed in the most intense heat 

 ever produced. It is a very bad conductor of heat, but conducts 

 electricity. Its property of condensing various gaseous bodies has 

 been already noticed, as well as the compounds which it forms with 

 some other elements. It has considerable antiseptic powers. [CABBO^.] 



It has been mentioned that certain impurities exist in the charcoal 

 of wood ; thus when 100 parts of old oak wood are entirely burnt, 

 there remain about 5 parts of ashes, and different woods furnish very 

 different proportions of them ; these ashes are principally carbonate of 

 potash [POTASSIUM], unquestionably derived from the decomposition 

 of some salt containing a vegetable acid, as the tartaric or malic. It 

 has been thought that the spontaneous combustion which charcoal has 

 been known occasionally to undergo, has been occasioned by a portion 

 of potassium having been reduced to its metallic state, and the sub- 

 sequent action of moisture upon it. For an account of the different 

 quantities of charcoal and ashes obtained from different kinds of wood, 

 see Dumas, ' Traiti; de Chimie,' tome i. p. 558 ; and see also in ' Phil. 

 Mag.,' vol. iii., a paper by M. Mushet, on the same subject. 



CHARCOAL, ANIMAL. [BONE BLACK.] 



CHARGE, in the practice of artillery, denotes the quantity of 

 powder placed in a gun, howitzer, or mortar, for the purpose of ex- 

 pelling the shot or shell by its explosion. 



The service-charge varies from one-sixth to one-third of the weight 

 of the projectile : the lower charges being used in the field, or in naval 

 actions ; and the higher in breaching the walls of fortresses. It is 

 evident that extensive ranges and great velocities of shot are not 

 required when artillery is directed against an enemy's columns or lines ; 

 and it is found by experiment that a ball which just pierces the 

 timbers of a ship will fracture them more than if it passed rapidly 

 through them. On the other hand, the greatest momentum is neces- 

 8ai-y on commencing the formation of a breach in a rampart faced with 

 brick or stonework, as the depth to which the shot will penetrate 

 is thereby increased; and therefore the highest charges are then 

 required. 



According to Dr. Hutton (Tract 34), different charges of powder, 

 when the weight of the ball remains the same, produce velocities which 

 are as the square roots of the weight of powder ; and when the weight 

 of powder is the same while that of the ball varies, the velocities are 

 inversely proportional to the square roots of the weight of the balls. 

 The Doctor states, also, that the greatest velocities are produced in 

 guns, the lengths of whose bores are equal to fifteen, twenty, and 

 thirty calibres, or diameters, by charges occupying f f) , ,, and ^ of the 

 lengths of the bores respectively ; and he adds, that by increasing the 

 quantity of the charge, the velocities increase till they amount to a 

 certain value, after which they decrease till the bore is quite filled with 

 powder. The charge producing the maximum velocity is greater as 

 the gun is longer ; but it does not increase in so high a ratio as the 

 length of the gun. 



CHARGE' D'AFFAIRES, one who transacts diplomatic business at 

 a foreign court during the absence of his superior, the ambassador. 

 The agents that bear this name also form a separate class, being the 

 chosen envoys or residents at the states to which other states do not 

 appoint diplomatist* of the higher grades. In this capacity the Charges 

 d' Affaires act for themselves, represent their country, and are inde- 

 pendent of any ambassador. In the ordinary routine and course of 

 promotion, the secretary of legation, or secretary of embassy, becomes 

 a Charge 1 d'Affaires. For their privileges and duties see AMBASSADOR. 

 In this year (1859) the British Charges d' Affaires on the diplomatic 

 list are all those to the various republics of South America, and to the 

 empire of Morocco. 



CHARIOT, a light sort of coach ; also, a car (currus), in which 

 men of arms were placed in fight. The name is derived from the 

 French word rhaii'ctte. Cars or chariots are of very early use. Tho 

 invention of them was attributed by the Greeks to Minerva (Horn. 

 ' Hymn, in Ven.' v. 12), on which account she was venerated at Athens 

 and various other places in Greece under the name of Hippia : nil'! 

 the honour of the invention was shared by Krichthonius, who, accord- 

 ing to Virgil, was supposed to have first harnessed horses to a car. 

 and to have introduced chariot-races at the P.-inathenffia which were 

 established by him. The ancient chariot had but two wheels, and 

 was open overhead. It appears to have been usually drawn bytwn 

 horses, but in races three and even four horses were not uncommonly 

 yoked to it. Of the Roman biga, or two-horsed chariot, a representa- 

 tion is given under BIOA. The three-horse chariot woo e&lM n 



