GLOSSARY. 301 



Chemical, relating to chemistry. " 



Chemical action, the action of one body upon another, by which it 

 alters its character ; as the decomposition of limestone by acids. 



Chemical union, the union of different substances, by a chemical pro- 

 cess, so as to form a different substance from either. 



Chit, the shoot of corn from the end of the grain. 



Chloric, relating to chlorine ; formed with chlorine. 



Chloride, a compound of chlorine and some other substance. 



Chlorine, a simple substance, formerly called oxymuriatic acid. In 

 its pure state, it is a gas, and, like oxygen, supports the combustion 

 of some inflammable substances. 



Chord, a line connecting the ends of an arc. 



Circle, a round figure, every part of which is equally distant from its 

 centre. The outer line i^ called its Circumference. A line drawn 

 from the centre to the circumference is the Radius, or Semi-diam- 

 eter. Two or more of these lines are called Radii. A right line, 

 drawn from one part of the circumference to another, through the 

 centre, is the Diameter. If the circle is divided into four equal 

 parts, by lines crossing each other in the centre, each part, or quar- 

 ter of the circle, is called a Quadrant. Any part of the circumfer- 

 ence is called an Arc. The space between two radii is an Angle. 

 The angle of a quadrant is a Right angle. If less than a quadrant, 

 it is an Acute angle. If greater than a quadrant, it is an Obtuse 

 angle. A line, drawn from one end of an arc to the other, is the 

 Chord of that arc. A line, drawn from one end of an arc, to the 

 radius proceeding from the centre to the other end of the arc, and 

 perpendicular to ihaj; radius, is called the Sine. A right line, touch- 

 ing the circumference of a circle and not cutting it, is called a Tan- 

 gent. A radius, continued beyond the circumference, till it meets 

 the tangent, is called a Secant. A line, drawn from the sine of an 

 arc, to the radius which is parallel to that sine, is called the Co-sine. 

 A line, drawn from the end of the radius to the secant, and parallel 

 to the co-sine, is the Co-secant. A circle is divided into three hun- 

 dred and sixty equal parts, called degrees. A half circle is one hun- 

 dred and eighty degrees, A quadrant is ninety degrees. The dif- 

 ference between an arc and a quadrant is called its complement ; 

 thus, of an arc of sixty degrees, the complement is thirty. 



Citric acid, the acid of lemons. 



Class, Order, Genus, Species, Family, &c. In Natural History, 

 animals, plants, minerals, &c., are arranged in different divisions, 

 for convenience in systematizing them. The objects are first ar- 

 ranged in Classes, each Class is divided into Orders, each Order 

 into Genera, each Genus into Species, and each Genus and Species 

 sometimes into Subgenera or Subspecies. The term Family is 

 sometimes used instead of Genus, and objects are often arranged 

 in Families. 



Clayey Soils. This term, Sir Humphrey Davy says, should not be 

 applied to soils which contain less than one sixth of impalpable mat- 

 ter. They are called argillaceous, and often aluminous soils. 



Cleaving, reverse ploughing, levelling down ridges. 



Closeharrow, a harrow with the teeth slanting forwards. 



26 F. c. 



