CHE 



CHL 



Marine charts are constructed in two 

 ways. 1. A plane chart represents the 

 meridians, as well as the latitudes, by 

 equidistant and parallel straight lines ; 

 and, consequently, the longitudes and 

 latitudes appear equal, differing from the 

 fact. 2. A Mercator's chart represents 

 the meridians as well as the circles of 

 latitude by parallel straight lines; but 

 the distances of the latter increase in a 

 determinate ratio from the equator to the 

 poles. 



CHEILO'GNATHA (xelAor, a lip, 

 fvdOoi, a jaw). An order of Myriapods 

 or Centipedes, in which the two man- 

 dibles and the tongue are united to form 

 a large lower lip. 



CHEILO'PODA (xelXor, a lip, wow, 

 iroSos, a foot). A family of insects, of 

 the class Myriapoda, or Centipedes, in 

 which the lower lip is formed by a pair 

 of feet. 



CHEIRO'PTER A (xeip, a hand, irrepov, 

 a wing). An order of mammiferous 

 quadrupeds, which have their extremities 

 connected together by a wing-like expan- 

 sion of the integuments, for the purpose 

 of flight, as in the bat. 



CHELE' ixh'^^)- A claw; particularly 

 applied to the bifid claw of the Crustacea, 

 the scorpion, &c. 



CHELI'CERA (x'7^^»1. a claw, Kepa^, a 

 horn). The prehensile claws of the 

 scorpion, which are the homologues of 

 antennae. 



CHELIOSO'MIDiE. A tribe of bi- 

 valved mollusca, which have a cartila- 

 ginous covering, analogous to that of the 

 chitons and the tortoises. 



CHELO'NIA ixeXwvf], a turtle). An 

 order of Reptiles, which have their ribs 

 immoveable, comprising the tortoises, 

 the turtles, &c. The body of these ani- 

 mals is enclosed in a shell, the upper and 

 arched portion of which is termed the 

 carapace; the lower plate is called the 

 plastron. 



CHELO'NID^ (xeXtii/rj, a turtle). The 

 Turtles ; a family of Chelonian reptiles, 

 distinguished by tlie incompleteness of 

 their shelly covering, and by the pecu- 

 liar modification of the feet for swim- 

 ming. 



CHEMICAL ATTRACTION. Elec- 

 tive attraction or affinity. These terms 

 denote the action by which the particles 

 of one class of bodies, when presented to 

 those of certain other classes, unite to 

 form new compounds, making a choice, 

 or election, of those with which they 

 unite. 

 75 



CHEMICAL COMBINATION. An 



intimate union of two or more substances, 

 which forms a compound differing in 

 one or more of its essential qualities 

 from those of its constituent bodies. 



CHEMISTRY. A term, of Arabic 

 origin, signifying the knowledge of the 

 composition of bodies, and of the changes 

 of constitution produced by their mutual 

 action on each other. 



CHENOPODIA'CEiE. The Goosefoot 

 tribe of Dicotyledonous plants, comprising 

 beet, mangel wurzel, spinach, &c. Her- 

 baceous plants or undershrubs, with 

 leaves alternate ; flowers small ; stamens 

 inserted into the base of the calyx ; ovary 

 superior ; fruit membranous. 



CHERT. A silicious mineral, nearly 

 allied to chalcedony and flint, but less 

 homogeneous and simple in texture. A 

 gradual transition from chert to lime- 

 stone is not uncommon. 



CHIAROSCU'RO (chiaro, light, o«- 

 curo, dark). In painting, the judicious 

 arrangement and combination of light 

 and shade, and of bright and dark 

 colours. 



CHIA'STOLITE. A mineral found 

 imbedded in clay-slate, resembling stea- 

 tite. Chiastolite-state, or rather clay- 

 slate, is a division of the Cumbrian group 

 of rocks; it is dark-coloured, and gene- 

 rally soft, containing crystals of the mine- 

 ral chiastolite. 



CHI'LDRENITE. A mineral found 

 in Devonshire, consisting of a phosphate 

 of alumina and iron. 



CHINA-CLAY. Kaolin. A variety 

 of clay prepared from decaying granite. 



CHINA GLAZE. A preparation for 

 printing blue frit, made from ten parts 

 of glass, two parts of lead, and three or 

 more of blue calx. 



CHINCHI'LLID^. The chinchilla 

 tribe ; a small family of the Rodentia, in- 

 digenous in South America, and valuable 

 in commerce for their furry skins. 



CHI'TINE (xiTwv, a tunic). A prin- 

 ciple discovered in beetles and other in- 

 sects, also called entomoline, and consist- 

 ing of the base of their external skeleton. 



CHITO'NID^. A family of Gastero- 

 pods, named from the genus Chiton, and 

 characterized by the presence of a pro- 

 tecting tunic-like shell, formed of many 

 portions, which are often in contact and 

 overlap one another. 



CHLORATES. The salts of chloric 

 acid, formerly called hyper-oxy muriates. 

 The principal are those of potash and 

 baryta. 



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