ACLINIC LINE 



25 



ACRE 



gen and oxygen are deadly poisons. Sul- 

 phuric acid, nitric acid and hydrochloric acid 

 are manufactured on a large scale, and are very 

 useful products in manufactures and elsewhere ; 

 some of their uses are related in detail in this 

 work in articles bearing those titles. See 

 CHEMISTRY; HYDROGEN; LITMUS; ACETIC ACID; 

 CITRIC ACID; CARBOLIC ACID; NITRIC ACID; SUL- 



I'Hl'RIC ACID. JJ.S. 



ACLINIC, aklin'ic, LINE, or the magnetic 

 equator, an imaginary irregular curved line 

 circling the earth in the neighborhood of the 



by a woody cup. The inhabitants of some 

 countries use acorns for food. Squirrels and 

 many birds, especially the jay, store them away 



ACLINIC LINE 



geographical equator. This line marks the 

 zero point, or perfect balance, in magnetic at- 

 traction between the north and south magnetic 

 poles. At all points along this line the mag- 

 netic needle always will balance itself horizon- 

 tally, having no dip. See DIPPING NEEDLE; 

 M \<;NKTISM. 



ACONCAGUA, ah kon ' kah gua, an extinct, 

 craterless volcano in Argentina, in the south- 

 ern part of the Andes Mountains. It is the 

 highest mountain in America, its height being 

 between 23,000 and 24,000 feet. A river of the 

 same name, 200 miles in length, rises on the 

 southern slope of the mountain and enters the 

 Pacific Ocean twelve miles north of Valparaiso, 

 Chile. 



ACONITE, ack' onite, a group of hardy 



plants of the buttercup family, consisting of 



about sixty species, all of which are poisonous. 



if ul medicines are made from their roots 



and leaves. Applied to the skin, these cause 



a feeling of numbness, and are used to deaden 



pain in some forms of rheumatism and neural- 



It taken internally they cause the heart 



to beat more slowly, and too large a dose kills 



by stopping the heart action. 



\V. 11 -known examples of aconite plants are 

 H-vane and monk's-hood. The blue or yel- 

 low flowers of these plants bear sepals of un- 

 equal size and shape, the upper one having 

 th> form of ;i helmet or hood. JJfA. 



ACORN, a' korn or a' hrn. th fruit of the 

 oak tree, consisting of a rounded nut covered 



VARIETIES OF ACORNS 

 a Bur oak c Chestnut oak 



b Live oak d Red oak 



as food for the winter, and many oaks have 

 grown from the acorns dropped by these little 

 harvesters. Such expressions as "Mighty oaks 

 from little acorns grow" are often used as fig- 

 ures of speech to show what may result from 

 small beginnings. The tree is described under 

 the title OAK. 



ACOUSTICS, akow' stiks or akoo' stiks, 

 from a Greek word meaning to hear, is a term 

 applied to that quality of a room or hall which 

 determines how easily sounds produced in it 

 may be heard. A room containing large, smooth 

 surfaces on the walls, floor or ceiling is said to 

 have bad acoustic quality, because these sur- 

 faces reflect successive sound waves sent out 

 by a speaker's voice, so that the words over- 

 lap and confusion results (see ECHO). The most 

 remarkable example of the acoustic properties 

 of a large room is to be found in the Mormon 

 Tabernacle at Salt Lake City, Utah, where a 

 whisper can be heard distinctly in all parts of 

 the room. See SOUND. 



ACRE, ah' kur or a' kur, or AKKA, a city 

 and seaport of Syria, at the foot of Mount 

 Carmel. In medieval times it was a place of 

 i importance, being the key to the Holy 

 Land, and in consequence it is famous for 

 many sieges. In 1104 it was taken by the Cru- 

 saders (see CRUSADES). In 1187 the Saracens 

 recaptured it, but it was recovered by Richard 

 Coeur de Leon, who gave it to the Knights of 

 Saint John of Jerusalem. In 1291 it was again 

 taken by the Saracens. Napoleon attempted 

 unsuccessfully to take Acre in 1799, when he 

 was approaching the years of his wonderful 



ACRE, a' ker, a measure of land consisting of 

 100 square rods, or 4340 square yards. In the 

 English system a square of land 208.7 : 

 each direction is equivalent to an a< 

 the metric system (which see) one hectare it 

 equal to 2.471 acres. The acre is used as a 



