EUD 



EVE 



De Marti, by experiments in Spain, ob- 

 tained the same uniformity of composition 

 (between il and 20 of oxygen in the hun- 

 dred parts) in the air, at places at a dis- 

 tance from each other; and he adds also, 

 as established by his experiments, that in 

 every state of the atmosphere, whether 

 with regard to temperature, to pressure, 

 as indicated by the barometer, to winds, 

 to humidity, to the season of the year, or 

 the hour of the day or night, the results 

 were precisely the same. (Journal de 

 Physique, t. iii. p. 173.) and more late- 

 ly the researches of Humboldt and Gay 

 Lussac, made with the view of determin- 

 ing this question, have established the 

 same conclusion. (Journal de Physique, 

 t. Ix. p. 152.) 



The instruments for subjecting atmos- 

 pheric air to such changes as may indi- 

 cate its proportion of oxygen have been 

 called eudiometers. When a mixture of 

 nitrous gas is to be made with atmosphe- 

 ric air, the most convenient apparatus con- 

 sists in a glass tube, closed at top, and 

 graduated by a diamond into cubic in- 

 ches and parts. The lower aperture may 

 be widened, in order that the gases may 

 more easily be passed up, and likewise to 

 afford the facility of its standing alone 

 upon the pneumatic shelf. It is likewise 

 usual and advantageous to fit a stopper 

 in the mouth by grinding ; a cubic inch 

 measure will be required fordetermining 

 the quantities poured up. A bottle will 

 do for this purpose, and the instrument 

 may be made very well by a chemist, 

 who is obliged to work for himself, by 

 taking any small bottle whatever, and 

 pouring its contents of water, by succes- 

 sive times, into the tube placed mouth up- 

 wards. By this means he will obtain a 

 graduation, which, whether of the cubic 

 inch or not, will answer the purposes of 

 eudiometry. 



When air is to be exposed to a liquid 

 sulphuret, which absorbs the oxygen, the 

 eudiometric tube may be immersed in the 

 liquid. Professor Hope, of Edinburgh, 

 has contrived a very simple, elegant, and 

 accurate apparatus for this purpose, an- 

 nounced in " Nicholson's Journal," iv. 

 210. It consists of a small bottle, of the 

 contents of about three ounces, intended 

 to contain the eudiometric liquid; into the 

 neck a tube is accurately fitted by grind- 

 ing, which holds precisely a cubic inch, 

 and is divided into a hundred equal parts, 

 and on one side the bottle, near its bot- 

 tom, there is a neck, into which a stopper 

 is ground in the usual manner. In the 



VOL. V, 



use of this apparatus, the bottle is first 

 filled with the liquid employed, which is 

 best prepared by boiling a mixture of 

 quick lime and sulphur with water, fil- 

 tering the solution, and agitating it for 

 some time in a bottle half filled with com- 

 mon air. The tube, filled with the gas 

 under examination, or with common air, 

 if that be the subject of the experiment, 

 is next put into its place, and on invert- 

 ing the instrument, the gas ascends into 

 the bottle, where it is brought extensively 

 into contact with the liquid, by brisk agi- 

 tation. An absorption of oxygen, if pre- 

 sent, ensues, and, to supply its place, the 

 stopper in the side of the bottle is opened 

 under water, a quantity of which rushes 

 into the bottle ; the stopper is then re- 

 placed under water, the agitation renew- 

 ed, and these operations are alternately 

 performed, till no farther diminution takes 

 place ; the tube is then withdrawn, 

 while the neck of the bottle is under 

 water, and after the tube has been 

 kept in this situation for a few mi- 

 nutes, the quantity of the diminution will 

 be seen by the graduated scale upon the 

 tube. 



Tubes fitted up for exploding a mix- 

 ture of hydrogen or other inflammable 

 gases with oxygen gas, have been call- 

 ed the eudiometers of Volta ; they are 

 usually made very strong, and are pro- 

 vided with two wires, which pass through 

 sockets cemented in holes drilled through 

 the glass, near the top, which is not per- 

 forated. The electric spark being pass- 

 ed between these wires gives fire to the 

 gases, not without some risk of blowing 

 out the confined liquid, or breaking the 

 glass. 



EVEN number, in arithmetic, that 

 which can be divided into two equal 

 parts : such are 4, 10, 40, &c. A num- 

 ber is said to be evenly even, when, being 

 even itself, it is measured by an even 

 one an even number of times: such is 32, 

 as being measured by the even number 8, 

 an even number of times 4. Evenly odd 

 number is, that which an even number 

 doth measure by an odd one ; such is 

 30, which 2 or 6, both even numbers, do 

 measure by 15 or 5, odd ones. 



EVERGREEN, in gardening, a species 

 of perennials, which continue their ver- 

 dure, leaves, &c. all the year : such are 

 hollies, phillyrias, laurustinus, bays, 

 pines, firs, cedars of Lebanon, &c 



EVERLASTING pea, the name of a 

 perennial plant of the vetch kind, which 

 grows naturally in some places, is easily 





