DEFINITION OF TERMS, 



73 



Centripetal force — That force by which 

 a body is every where impelled, or any 

 way tends toward some point as a centre, 

 such are gravity, or that force whereby 

 bodies tend toward the centre of the earth. 

 Magnetical attraction whereby the load 

 stone draws iron, and that force whatever 

 it be, whereby the planets are continually 

 drawn back from right lined motions and 

 made to move in curves. 



Ceruse or Ceruss — White lead, a sort 

 of calx of lead made by exposing plates 

 of that metal to vapor of vinegar. 



Charcoal — According to modern che- 

 mistry is an oxide of carbon; but as a por- 

 tion of carburetted hydrogen is obtained 

 after it ceases to yield carbonic acid at a 

 strong heat; it is thought to contain hydro- 

 gen also, and is therefore concluded to be 

 a triple compound composed of carbon, 

 hydrogen and oxygen. 



Chemistry — Is that branch of science, 

 the object of which is to ascertain the sim- 

 ple substances or elements of bodies, the 

 properties of these and their action on each 

 other. 



C^hord — In geometry is a right line 

 •drawn from one extremity of an arch of a 

 circle to the other. 



Chrysalis or Jiurelia — In natural his- 

 tory. a state of rest and seeming insensi- 

 bility, which butterflies, moths, and sever- 

 al other kinds of insects must pass tlirough 

 before they arrive at their winged or most 

 perfect state. 



Chyle — In animal economy, a milkey 

 fluid secreted from the elements by means 

 of digestion. 



Clay — Is a mixture of alumina and si- 

 lica in various proportions; besides these 

 clay often contains carbonate of lime, of 

 magnesia, barytes, oxyde of iron, ^'C spe- 

 cific gravity is from 1. 8 to 2.68. A speci- 

 men of potters clay from Dreux analyzed 

 by Vauquelin contained 

 43.5 Silica. 

 33.2 Alumina. 

 3.5 Lime. 

 1,0 Iron. 

 18.0 Water. 



99.2 

 Indurated clay does not diffuse itself in 

 water but falls to powder. Discovers but 

 little ductility, colors, gray, yellowish, 

 bluish, greenish, reddish, brownish. 



Cochineal — This article is esteemed a 

 great cordial, suJorifiio, alexipharmic, and 

 febrifuge, and much used by dyers and 

 painters, the high crimson color it affords 

 being scarcely equalled by any thing, and 

 making according to their different ma- 

 nagement of it all the degrees and kinds 

 of red. 



Cohesion — The force called cohesion is 

 inherent in the particles of all bodies, ex- 

 cept caloric and light, for all bodies ex- 

 cept these constantly exist in masses com- 

 posed of an indefinite number of particles 

 united together. 



Combustion — In every case of com- 

 bustion oxygen combines with the burn- 

 ing body. 



When a combustible body is raised to a 

 certain temperature, it begins to combine 

 with the oxygen of the atmosphere, and 

 this oxygen during its combination, lets 

 go the caloric and light with which it is 

 combined while in the gaseous state. 

 Hence their appearance during evei*y com- 

 bustion. Hence also the change which 

 the combustible undergoes in consequence 

 of combustion. 



Concentric — In mathematcs some- 

 thing that has the same centre with ano- 

 ther, it stands in opposition to excentric. 



Cone — In Geometry, a solid figure hav- 

 ing a circle for its base, and its top termi- 

 nated in point or vertex. 



Conic Sections-Are curved lines form- 

 ed by the intersections of a cone and a 

 plane; some of the uses of which are as 

 follows. Any body projected from the 

 surface of the earth describes a parabola, to 

 which the direction wherein it is project- 

 ed is a tangent and the distance of the 

 directrix is equal to the height from which 

 a body must fall to acquire the velocity 

 with which it is projected: hence the pro- 

 perties of the parabola are the foundation 

 of gunnery. A thorough understanding 

 of conic sections is considered of great im- 

 portance in learning the mathematics. 



Convex — Is a name given to the exteri- 

 or surface of gibbous or globular bodies, in 

 opposition to the hollow inner surface of 

 such bodies which are called concave. Thus 

 we say, convex lens, mirror,superfices,4'c. 



Copal — A substance of great impor- 

 tance as a varnish obtained from the rhais 

 copalinum, a tree in North America, speci- 

 fic gravity of copal varies from 1.045 to 



