EAR MARK. 



EARTHS. 



consequently, he has a complete power over | 

 the muscles attached to them, and can turn 

 them in every direction. It is probable that 

 the organ of hearing is the safeguard of the 

 horse in his natural state. He is ill adapted for 

 combat; his swiftness of foot and his acute- 

 ness of hearing are therefore requisites to him 

 of the utmost importance. 



EAR MARK. A mark on the ear by which 

 shepherds know their sheep. Cattle, hogs, and 

 other animals are sometimes marked in the 

 same way, by notching, clipping, or slitting 

 the ear. 



EARNEST (Sax. eojinerr; Fr. arrhes; Dan. 

 ermiz f'ge). In commercial law, the sum ad- 

 v;mrr<J by the buyer of goods in order to bind 

 the seller to the terms of the agreement. As to 

 what amounts to sufficient earnest, Blackstone 

 lays it down, that " if any part of the price is 

 paid down, if it is but a penny, or any portion 

 of the goods is delivered by way of earnest, it 

 is binding." To constitute earnest, the thing 

 must be given as a token of ratification of the 

 contract, and it should be expressly stated so 

 by the giver. (Chilly's Com. Lmr, vol. iii. p. 289 ; 

 JM k Cnflodk'l Com. Dirt.) 



EARS of Corn (Sax. *hhep.). The spike 

 or head containing the seeds of wheat, Ac. 



In the United States the term ear as applied 

 t> -jrain, refers almost exclusively to that of 

 Indian corn. 



EARTH (Sax. capo.). This word was an- 

 ciently employed to signify one of the four 

 elements of which all matter was supposed to 

 be funned ; namely >,/</T, tt-mn; and earth. In 

 the present period, the word in common lan- 

 guage has two meanings ; it implies either the 

 globe we tenant, or the soil on which plants 

 vegetate. In this work it has reference to the 

 latter. The soil, as well as the rocks, &c., of 

 which our planet is formed, is composed of a 

 variety of substances, such as lime, silica, 

 alumina, magnesia, &c., to which chemists 

 long since gave the name of earths ; and 

 although by the researches of Sir H. Davy and 

 others, these earths have been shown to be, in 

 reality, metallic oxides that is, metals united 

 with oxygen yet the term earth is so well and 

 so extensively known, that I should, even if 

 this was intended to be a chemical dictionary, 

 retain it. The following is the composition of 

 the four earths most commonly met with by 

 the farmer in his land, or in the crops which it 

 supports : 



Lime: a compound of a peculiar metal called 



Calcium 

 Oxygen 



Part*. 

 71-42 

 26-58 



loo 



Alumina (clay) : a compound of, 

 Aluminum ------ 



Oxygen ...... 



43-105 

 100 



Magnesia : a compound of the metal 



Magnesium 

 Oxygen 



100 



Silica, which is by modern chemists c.assed 

 with the acids, is a compound of a metal called 



Silicon 

 Oxygen 



50112 

 100 



In this place, however, our business is with 

 the earths only so far as their uses to vegeta- 

 tion are concerned. 



EARTHS, their Use to Vegetation. In the in- 

 vestigation of the use of the earths to vegeta- 

 tion, not only as regards their position as 

 necessary portions of all cultivated soils, but 

 as forming the essential constituents of most 

 vegetable substances, several very important 

 circumstances will present themselves to the 

 notice of the cultivator. The order and the 

 regularity with which these earths are found in 

 pl-ints is most remarkable; the harmony, too, 

 with which the various chemical ingredients 

 are arranged, the uniform manner in which 

 they are absorbed by the roots of the plant and 

 distributed in its juices, cannot escape our at- 

 tention, nor fail to excite our gratitude for the 

 benevolence and the wisdom displayed in the 

 contrivance. Thus we shall find, as we pro- 

 ceed in our researches (to give only a .single 

 instance), that the earth silica (flint) abounds 

 in the straw of the wheat plant, where its pre- 

 sence helps to impart the requisite degree of 

 strength and hardness to the stem; but scarce- 

 ly a chemical trace of this earth is discoverable 

 in the flour of the seeds of the same plant, for 

 there its presence in our food would be worse 

 than useless. 



Let not, however, the reader, when he is 

 considering the discoveries of vegetable che- 

 mistry, feel surprised that more has not been 

 accomplished by the chemical philosopher in 

 that important branch of science. There are 

 many reasons why the discoveries in this 

 branch of chemistry have been gradual, and 

 only by slow degrees : he may be assured that 

 the difficulties which attend the chemist when 

 he is investigating the properties of organic 

 matter, are more than usually numerous ; for 

 the living plant, in many instances, seems en 

 dowed with powers that appear even to neu 

 tralize the effects of chemical attraction and 

 repulsion : thus the earths and alkalies, to give 

 one instance only, are often found in juxtapo- 

 sition with uncombined vegetable acids. The 

 roots of most plants, also, are endowed with a 

 remarkable capacity of absorption ; not only 

 do they absorb water, the gases of the atmo- 

 sphere and those formed by putrefaction, but 

 they take up earths, alkalies, and saline sub- 

 stances ; and, besides doing this with a regu- 

 larity which is almost unvaried, they exercise 

 a power of absorbing certain saline bodies 

 when dissolved with others in water, and of 

 leaving the others in solution, which shows 

 them to be endowed with properties of a very 

 remarkable nature. Some curious experiments 

 were long since made by M. Saussure on this 

 interesting question. " When various salts 

 were dissolved at once in the same solutions,* 

 says Dr. Thomson, "and plants made to vege 

 tate in them, it was found that different propor 

 tions of the salts were absorbed. The follow 



427 



