ELE 



ELM 



eter consists of two very small pith 

 balls suspended from a small con- 

 ductor by very fine wire or tliread ; 

 upon the ))rmciple that bodies simi- 

 larly electrified repel each other, these 

 diiicrffc upon the reception of very 

 minute quantities of electricity. Two 

 thin slips of gold leaf are also simi- 

 larly applied ; and, to prevent the in- 

 fluence of the agitation of the air upon 

 them, they are suspended in any con- 

 venient way under a glass shade. 

 The other forms of electrometers 

 generally act upon the same princi- 

 ple, being respectively adjusted to 

 the varying degrees of quantity and 

 intensity. 



ELECTROPHORUS (from v^iSK- 

 Tf)ov, and <pepu, I carry). This instru- 

 ment consists of a flat, smooth cake 

 of resin. A, which is rendered nega- 

 tively electrical by friction ; a plate 

 of brass with a glass handle is then 

 placed upon it, and be- 

 comes electropolar by in- 

 duction. The brass plate, 

 •^ having been touched by 

 the finger while lying 

 upon the resin, is afterward lifted off 

 by its glass handle, and gives a spark 

 of positive electricity. The same 

 operation may be indefinitely repeat- 

 ed. This instrument is sometimes a 

 convenient substitute for the electri- 

 cal machine, and is elegantly applied 

 to inflame a jet of hydrogen gas in 

 Volla's inflammable air lamp. 



ELECTROPOLAR. A term ap- 

 plied to conductors, one end or sur- 

 face of which is positive, and the oth- 

 er negative : a state which they com- 

 monly exhibit when under the influ- 

 ence of induction. 



ELECTROSCOPE {iromnleKTpov, 

 and oKOTTEu, I sec). An instrument 

 for rendering electrical excitation ap- 

 parent by its effects. The gold leaf 

 electrometer and other similar ar- 

 rangements are electroscopes. 



ELECTUARY. Any medicine of 

 a thick or solid consistence, made up 

 with sugar. 



ELEMENTS. In chemistry, bod- 

 ies which have never been decompo- 

 sed or resolved into their components 

 by means we possess. Hydrogen, 

 256 



oxygen, sulphur, nitrogen, phospho- 

 rus, chlorine, and the metals are the 

 commonest elements. There are 54 

 already known. 



ELEVATION. In architecture, 

 the representation of the vertical view 

 of any building, &c. 



ELLAGIC ACID. The insoluble 

 gray powder which subsides from an 

 infusion of galls ; it is isomeric with 

 gallic acid, C7 H3 O3.— (Pe/oure.) 



ELM. Ulmus. The principal spe- 

 cies are, the Americana, white ; and 

 fulva, slippery ; the Thomas, U. race- 

 mosa ; river, nemoralis, and Whahoo, 

 alata, are also indigenous. Mr. Nutt- 

 al mentions a species resembling 

 the sub-evergreen C/unensis, found on 

 the Red River. The Chinese is an 

 ornamental tree, to be had at the nur- 

 series. 



The white elm is found from Nova 

 Scotia to Georgia, delighting in rich, 

 wet lands ; in perfection, it reaches 

 100 feet, with a stem of 4J feet diam- 

 eter. The bark is gray and deeply 

 furrowed. The tree is of great beau- 

 ty and stateliness, the heart wood 

 dark brown, and ornamental, but so 

 brittle as to be of inferior value. It 

 is used improperly for naves, and oc- 

 casionally in Maine for keels. The 

 bark, soaked in water and pounded, 

 furnishes bass for the bottoms of 

 chairs. 



The slippery, red, or moose elm is 

 commonly diffused, prefers a rich but 

 dry soil ; it may attain 60 feet, by 18 

 or 20 inches m diameter. The wood 

 is of a dull red, and consists in a 

 great measure of heart : it is coarse, 

 and splits, but is highly esteemed for 

 blocks, railings, and building purpo- 

 ses, as it stands moisture tolerably 

 well. The bark is brown, and, boiled 

 in water, yields a nmcilaginous solu- 

 tion used in medicine and as a drink. 

 It resembles the European Dutch elm, 

 but neither this nor the preceding pos- 

 sess the admirable qualities of the V. 

 campcstris of Europe. 



The Whahoo is smaller, and a 

 Southern tree ; the wood is deep 

 chocolate, fine, hard, and durable ; it 

 is esteemed for naves. It is remark- 

 able, as well as the Thomas elm, for 



