ELE 



ET-E 



iKiPnded as a cheap hedge. On the 

 other hand, it is a great nuisance on 

 wot hinds, from the rapidity of its 

 growth, but may i)e destroyed by cut- 

 ting down two or three times during 

 the summer, and grubl)ing in the fall. 



ELDER. BOX. A common name 

 for the ash-leaved maple. 



ELECAMPANE. Imtia Hclcnivm. 

 A naturalized composite perennial, 

 yiekling roots with a bitter, aromatic 

 taste. It is of little importance. 



ELECTIVE AFFLMITY. A chem- 

 ical term, meaning the preference ex- 

 erted by a body to combine with an- 

 other in place of one already in union. 

 Thus, potash will unite with sulphu- 

 ric acid, although it be already com- 

 bined with iron ; the iron is separa- 

 ted, and gives place to the potash, 

 which is preferred or elected. It is 

 governed by electrical forces, like all 

 other cases of chemical union. 



ELECTRICITY. A peculiar in- 

 fluence or force, which is made evi- 

 dent by attracting light bodies, pro- 

 ducing a spark, or jarring the body of 

 animals. Some consider it material, 

 although its weight cannot be meas- 

 ured ; hence the term imponderable, 

 applied to electricity, light, and heat. 



"This truly extraordinary power of 

 matter, independent of the interest 

 that always belonged to it, has of 

 late years acquired much importance, 

 from its influence over chemical phe- 

 nomena and its connexion with those 

 of magnetism. When a clean glass 

 tube is rubbed with the dry hand, or 

 with a piece of silk, it attracts and re- 

 pels any light substances — such as 

 feathers, bran, or little pieces of pa- 

 per — which are brought near it ; a 

 stick of sealing-wax rubbed upon dry 

 flannel exhibits the same appearan- 

 ces, and, to a superficial observer, 

 seems to be exactly in the same state 

 as the glass ; and they are said to be 

 electrically excited. But, on more 

 close examination, it is found that 

 when the light bodies are attracted by 

 excited glass, they are repelled by exci- 

 ted sealing-wax, and rice versa, so tiiat 

 the glass and wax are said to he in 

 opposite electric states ; and hence tlie 

 terms vitreous and resinous, or positive 



and negative electricity. But these 

 two states are always coexistent ; 

 thus, when the glass is rubbed by silk 

 the glass becomes positive, but the 

 silk becomes negative ; and in the 

 case of sealing-wax rubbed by flan- 

 nel, the wax is negative, but the flan- 

 nel is positive. 



" A similar excitation of electrici- 

 ty is seen in an infinity of other ca- 

 ses ; as when we rub a cat's back 

 with the hand, or a piece of silk rib- 

 and is drawn briskly between the fin- 

 gers, or a sheet of paper rubbed with 

 India rubber, or a metal rod with a 

 silk handkerchief. These, and other 

 extraordinary phenomena connected 

 with them, are hypothetically refer- 

 red to the presence of a peculiar form 

 of matter, called the electric fluid ; it 

 is supposed to appertain to all mat- 

 ter, but to become evident only when 

 in redundance or deficiency. When 

 glass is rubbed with silk, the equilib- 

 rium of the electric fluid is disturbed, 

 the silk imparts it to the glass ; and 

 hence the former, losing electricity, 

 becomes minus or negative, and the 

 latter, acquiring electricity, becomes 

 plus or positive. This is commonly 

 called ' Franklin's theory,' having 

 been proposed and defended by that 

 celebrated electrician. Others have 

 assumed the existence of two fluids 

 as essential to the explanation of 

 electrical phenomena ; both equally 

 subtile, elastic, and universally diff"u- 

 sed, and each highly repulsive as to 

 its own particles, and attractive of 

 those of the opposite kind. Electri- 

 cal quiescence is referred to the com- 

 bination of these fluids and their con- 

 sequent mutual neutrahzation ; and 

 electrical excitation is the conse- 

 quence of either being free or in ex- 

 cess. It is supposed that they are 

 separated by friction, and by all those 

 other causes which give rise to the 

 appearance of free electricity. Either 

 of these hypotheses may be adopted 

 as facilitating the explanation of elec- 

 trical phenomena, and as conferring 

 meaning (m terms which would oth- 

 erwise be unintelligible: of the two, 

 the simplest, or that which refers the 

 phenomena to one fli^id, js perhaps 



3.51 



