SCIENCE, EDUCATION, RELIGION 



Acetic Acid. An acid produced by the 



oxidation of common alcohol, and of many other 



organic suh-tances. Pure acetic acid has a very 



sour id pungent smell, bums the skin, 



and is poisonous. From freezing at ordinary 



58 or 59^) it is known as glacial 



acetic arid. Vinegar is simply dilute acetic acid, 



ami is prepared by subjecting wine or weak 



t to tin* action of the air; also from malt 



which has undergone vinous fermentation. 



ic acid, both concentrated and dilute, is 



ly used in the arts, in medicine, and for 



i -urposes. 



Acetylene. A gaseous hydro-carbon; it 

 constituent of coal-gas, and burns with a 

 it, smoky flame. A method of preparing 

 ylene in large quantities has been recently 

 1, by the use of carbide of calcium, form- 

 erly a rare and expensive product, but now 

 manufactured cheaply and abundantly in the 

 el.-ctric furnace. When this substance is thrown 

 into water a rapid chemical transformation takes 

 place, and acetylene is given off as one of its 

 products. It has also been discovered that if 

 is be passed through pipes and burned at 

 ! aperture, like ordinary illuminating gas, 

 it yields an intense white flame, surpassing in 

 brilliancy any light known but the arc electric 

 liirht. By compression, acetylene can be re- 

 duced to the liquid state, and if permitted to 

 -lowly into pipes, can be burned for house 

 illumination. 



Arid. A class of compounds whose general 

 'ies are: solubility in water; sour taste; 

 of reddening litmus; faculty of decom- 

 _ carbonates with effervescence ; and the 

 power of neutrali/inir alkalies and bases, form- 

 ing salts. The progress of modern chemistry is 

 gradually rendering the term m-/V/x less definite; 

 and it is not improbable that it will be dropped 

 altogether in strictly scientific writing, although 

 nary language it will be retained as a 

 convenient term for expressing a very wide class 

 \11 the above characteristics are 

 M'ldom possessed together, many acids having 

 only one or two of these properties, and some 

 nces which are not ; : all of 



it arid is not soluble in water, 

 has no sour taste, and does not redden litmus. 

 V roii sties (a-kou'*tik*). The SCUM, 



It teacb MB, nature, and phe- 



i of such vibrations of clastic bo,, 

 be oruan of hearini: ; tin- manner in which 

 sound is produced, if through air 



and other media, the doct: l.'Cted HOlind 



the properties and effects of different 

 including musical sounds or not* 

 the structure and tin- organ of 1. 



I lie propagation of sound is analogous to 



liirht., both being due to vibrations which 



ce successive waves, and Newton was the 



-how that its propagation tlirom 

 ; depended upon the elasticity of that 



medium. Regarding the intensity, reflection, 

 and refraction of sound, much the same rules 

 apply as in light. In ordinary coses of hearing 

 the vibrating medium is air, but all sub- 

 capable of vibrating may be employed to propa- 

 gate and convey sound. When a bell is struck 

 its vibrations are communicated to the particles 

 of air surrounding it, and from these to particles 

 outside them, until they reach the ear of the 

 listener. The intensity of sound varies inversely 

 as the square of the distance of the body sound- 

 ing from the ear. Sound travels through the 

 air at the rate of about 1,090 feet per second; 

 through water at the rate of about 4,700 feet. 

 Sounds may be musical or non-musical. A mu- 

 sical sound is caused by a regular series of ex- 

 actly similar pulses succeeding each other at 

 precisely equal intervals of time. If these con- 

 ditions are not fulfilled the sound is a noise. 

 Musical sounds are comparatively simple, and 

 are combined to give pleasing sensations accord- 

 ing to easy numerical relations. The hudnc^s 

 of a note depends on the degree to which it af- 

 fects the ear; the pitch of a note depends on the 

 number of vibrations to the second which pro- 

 duce the note; the timbre, quality, or character 

 of a note depends on the body or bodies who-e 

 vibrations produce the sound, and is due to the 

 form of the paths of vibrating particles. The 

 gamut is a series of eight notes, which are called 

 by the names, Do, Re, Mi, Fa, Sol, La, Si, Do, ; 

 and the numbers of vibrations which produce 

 these notes are respectively proportional t <> - 1 . 

 27, 30, 32, 31 i. Ki. i:,. 48. The numerical value 

 of the interval between any two notes is given 

 by dividing one of the above numbers corre- 

 sponding to the higher note by the numK 

 responding to the lower note. The in 

 from Do to each of the others are called a ft 

 a major third, a fourth, a fifth, a sixth, a ft 

 and an octave, respectively. The interval from 

 La to Do 2 is a minor third. An interval of f is a 

 major tone; yis a minor tone; {f is called a 

 limma. The properties of sound he- 



matically investigated by Bacon and (Jalileo, 

 l>ut it remained Tor Newton, Lagrange. Kuler, 

 I.aplace. Helmholtz, etc.. to bring the MM- 

 '.ts present state. 



Aerolite. A stone falling from the air or 

 atmospheric regions; a meteoric >tone; p 

 suppose them to !><> projected ly 1 . 

 anoes, by oth< thought 'to In- for 



in the air by the union of simpler form* of matter 

 volatilized from the earth's surface; l>ut 

 are doubtless cosmical btwiies of the mine na 

 as shooting-stars, revolving round the earth, 

 falling when they come within its attraction. 

 Analyzed, they are found to consist of 

 iwo of the elements found in terrestrial minerals, 

 he mo-t prominent being malleable metallic 

 n>n and ni< 



Agricultural Colleges. Educational 

 institutions, chiefly under government patron- 



