IQASURIC ACID. 



IMMORTALITY. 



or of character*, manner*, and sentiments ; or of tbaic in c.-n[ 



with the appearances of nature. The epitaph, the inscription, the 



, and moit of the apiatlss of poet* writing in their own persons, 

 belong to thi. class." ( Preface' to Wordsworth's Poems.') In Greek 

 the bucolic poem* of Theocritus are called idylls ; awl all buculio 

 poetry [Br roues] may be included under thU luuue; though the 

 indents did not, any more than ourselves, confine the name to bucolic 

 poetry, at may be seen by referring to the ' Idyll* ' of Ausoulus. In 

 English poetry, the ' Seaaoo* ' of Tbomaon, Shenstones ' School- 

 mistress,' the 'Cotter's Saturday Night' of Burns, the ' Allegro ' and 

 Psnseroso' of Milton, BeattUi 'Minstrel, 1 Goldsmith's 'Deserted 

 Village,' Ac. belong to IhU class ; Mr. Tennyson in his ' Idylls of the 

 King.' has applied the term Idyll in a still more extended sense. 



IOA8UBIC Ai'lh. [Nix VOMK A, ALKALOIDS or.] 



luvM'RIXK. [Xtx Voxicji.AUnlouUnf.] 



I..MS FATI'l's. a meteor resembling a flame, said to Boat in the 

 atmosphere at a few feet above the surface of the ground. It is stated 

 to be generally ubsenred by night, either stationary or in motion, over 

 manhee or burial grounds; but in the ' Philosophical Transact!. .MS.' 

 for 1894, there is an account of some ricks of bay being burnt at 

 Dolgellv, in the preceding year, by a vapour like a weak blue flame 

 which came from the sea. Derham (' Phil. Trans.' 1729) relates that 

 be observed about a decayed thistle a flame in motion, which receded 

 from him as he advanced towards it ; and Beccaria states that be saw 

 one which seemed fixed to a spot about two feet above some stones 

 near a river: this philosopher observes that such meteor* are moat 

 usually witnessed during a fall of rain or snow ; he adds that they 

 often appear on clayey soils, and that they have been seen to give out 

 sparks. Trebra (' Deutscber Merkur,' Oct. 1788) mentions that he saw 

 at Zellerfeld a meteor which at first approached him and afterwards 

 needed from him to a distance of 500 paces ; he adds that it then 

 disappeared, and at the end of half an hour it again became visible. 



Occasionally such meteors have been observed to follow or advance 

 towards a spectator ; but in general they appear to recede on being 

 approached, and it has happened that from their resemblance to the 

 flame of a distant lamp, they have led the unwary traveller into dan- 

 gerous swamps. Little confidence can be placed in the description* 

 given of them, as few persons have been able to examine them with 

 due attention ; and commonly they have been observed under the 

 influence of an ill-regulated imagination rather than a philosophical 

 spirit. 



A plausible hypothesis which has been proposed in order to account 

 for this phenomenon is that a phosphuretted or a carburetted hydro- 

 gen gas, produced by the decomposition of animal or vegetable sub- 

 stances, rises from the ground or from stagnant water, either small in 

 quantity and occupying a single spot, or in great abundance and then 

 becoming a train or a horizontal column of vapour of variable dimen- 

 sions : such gas may take fire by electricity or spontaneously, at a spot 

 where the atmosphere is particularly free from moisture; and the 

 flame communicating itself successively to other parts of a line or 

 column, the latter being in a state of undulation from the agitation* of 

 the atmosphere, will give rise to the appearan'* of a motion from place- 

 to place. The brightness of the meteor will change with the varying 

 quantity or purity of the gas ; and its temporary disappearance may 

 be caused by the quantity being in some places too small to render tin- 

 Hum- visible. Phusphurettod hydrogen would inflame spontaneously 

 on coming into contact with atmospheric air, but no hydroc.irl.un. u 

 must be objected, is spontaneously inflammable. There is a great 

 dearth of satisfactory observations on moving lights seen in nature, 

 an<l the entire subject w at present in obscurity. Electrical excitation, 

 true phosphorescence, spontaneous inflammation, combustion otherwise 

 occasioned, may all produce such lights, but whether such causes are 

 really so operative, ami whether their effect* have been described as 

 iffnri/ntni, remains to be proved. 



iri>\: INrAXI.KM'KXrK. These terms refer to that 

 nrnuei Ij of bodies, by which they (five out light, when raised to certain 

 high temperature*, the quantity of light increasing with the U'iii| 1.1 

 tore within certain limits. At first it is of a dingy red, or worm-red as 

 it i sometimes called ; then bright red, indicating what is called a 

 dkeny-rrd heat ; at a higher temperature we have an OTYIIK/-- or yellow- 

 lint, and lastly a irAiCr heat, when the light is painful to the n 

 Humphry Davy's experiments placed the degree of incipient lumi- 

 nosity in the dark at about 810*, but a dull red visit 1.- in daylight is 

 probably equal to 1000', a full red heat 1200, an orange heat 1700", 

 a white beat 8000, and the high white heat of a good wind furnace 

 (according to Daniel 1 1 about 8300*. These remarks apply to bodies 

 which can be raised to these high temperatures without changing their 

 state. Most bodies are dissipated or destroyed before they attain the 

 temperature necessary for ignition, and if heated in the air they inflame 

 and undergo mmlm-tnm. 



I I.KI'S, or ILIAC PASSION, Is a name given to a severe form of 

 telsstiml disease, characterised by violent griping pain around the 

 th* uml>ilicn*. s|>mm and retraction of the muscles of tin- al-l-i... n. 

 obstinate eostiveoeas, and vomiting. These symptoms are however 

 common to several very different conditions of the bowels ; they occur 

 fa ^evere cases of colic [CoLic] from spasm, or as some suppose, 

 paralysis of a portion of the intestinal canal, but more commonly they 

 are the result of some mechanical obstruction of the canal, as by intus- 



susception, internal hernia, unnatural adhesions between adjacent folds 

 of intestine, Ac. [Hiiuna.] The treatment must therefore vary accord- 

 ing as one or other of these conditions is presumed to exist In the 

 first class of cases the remedies adapted for colic, combined with 

 active purgatives, should be employed, while in thoss attended with 

 mechanic*! obstruction, in which there is always great tendency to 

 inflammation of the intestines, bleeding should be had recourse to, 



together with purgatives combined with opium, stimulant enemata, and 

 anodynes. 



ILICIN, a neutral crystalline vegetable principle, obtained by pre- 

 cipitating a decoction of holly-leaves (/fer <K/i/Wi'inn) by di -acetate of 

 lead, evaporating the filtered liquor, and treating the residue with 

 boiling absolute alcohol; by spontaneous evaporation there are pro- 

 duced transparent brownish-yellow crystals, which are bitter, and 

 readily soluble in water, but not in ether. The solution is not pre- 

 cipitated by metallic oxides. This substance has been recommended 

 as a powerful remedy in dropsy and intermittent*. 



ILLEGAL CONTRACT. [AoREEMEST; POBLIC POUOT.] 



ILLUMINATING. [PALEOGRAPHY.] 



IL.MENIC ACID, [tuanrat] 



ILMENIUM (II). A mineral first called Ura*o-ta*lalH has long 

 been known in the neighbourhood of the Ilmen Mountains, in Siberia ; 

 but from the fact that it contains no tantalic acid, M. Rose has 

 altered its name to Kanuumtilf, it being principally found at Samanki. 

 M. Hermann, however, gives to this mineral the name Yllro-il 

 asserting that it contains the oxide of a new metal analogous to tanta- 

 lum, and to which he has given the name Jlmraiitin. 



l/m-itic XriW(IlO,),the binoxide of ilmeniiim, is the form, according 

 to Hermann, in which the new metal exists in ytt.ro ilmonite. M. Rose, 

 however, insists that the so-called ilinenic acid is only niobic acid, with 

 a small quantity of tungstic acid, and that a mixture of these latter 

 acids exhibits all the re-actions assigned by M. Hermann to ilinenic acid. 



The existence of ilmeniiim, therefore, as a separate and distinct 

 metal, is not at present satisfactorily established. 



IMABEN ZILE (C,,H,,NO,). An ammoniacal derivative of benzile. 

 10 OBOCP, Benalt.] 



1MAGKS, I.I.KCTRIC, OPTICAL, THERMOORAPHIC, Ac. 



[ItllKATH-FUiVRKs; ELECTRICAL IMAGES; LEH8 ; LlOHT.] 



1 M AGINARY. [NEGATIVE AND IMPOSSIBLE QUANTITIES.] 



I M A t i I X ATION denotes in its widest sense that faculty of the mind 

 by which it produces at will thoughts or ideas as materials for every 

 other mode of the mental activity. It is often employed in a narrow 

 acceptation as synonymous with fancy, which properly is only a par- 

 ticular species of imagination combined with judgment. Still narrower 

 is the domain of this faculty according to the definition of Dr. Reid, 

 who confines it to a lively . of the objects of sight, and 



makes the imagination to differ from conception only as a part from the 

 whole. And r-itnilarly Addison teaches that " the pleasures of imagi- 

 nation are such as arise from visible objects, since it is the sense of 

 sight that furnishes the imagination with its ideas." In its widest 

 signification however imagination is coextensive with invention, fur- 

 nishing the writer with whatever is most happy and appropriate in 

 language, or vivid and forcible in thought. In the same manner it 

 is the imagination that suggests to the scientific inquirer those bold 

 conjectures of analogy or difference which lay open the secrets of 

 nature and multiply ita usefulness to man. Indeed, to adopt the 

 language of Dugald Stewart, " All the objects of human knowledge 

 supply materials for her forming hand ; diversifying infinitely the 

 work "she produces, while the mode of her operation remains essentially 

 uniform." 



It is in thin illimitable activity that imagination differs from con- 

 coption, which also is a reproductive faculty, but apparently mere 

 passive potentiality to bring forth certain given and particular ideas ; 

 while the former, when once awakened by the presentation of a 

 thought, produces out of its storehouse of ideas all the manifold varia- 

 tions of similar and dissimilar. In this procedure, while it is bound 

 indeed by the general Isws of association, it is yet free to choose- the 

 1 of its combinations. Accordingly every nge and every sex, 

 every form of government and of religion, is said to have its special 

 succession ; and what is colled a knowledge of men consists in nothing 

 else than a knowledge of the train in which their ideas respectively 

 succeed to each other. 



A disordered imagination exhibits itself under various forms or 

 characters; as the fantastic, the fan.-itic, and the enthusiastic. 



<>n the particular character of the imagination d< pends much of the 

 happinem or mi-, ry of the individual. Acting upon human hopes 

 and fears, it assumes the name of sensibility, and by the l.ri 

 sombre images with which it nils the distant prospect of life U 

 a double relish to every enjoyment or gives a keener edge to sorrow 

 and misfortune. 



IM \SARATIC ACID. [IxDioo.l 



IMASATIX. [Ixi.ioo.] 



IMI'.KCILITY. [IxsAMTT.] 



IMKSATIX. [iNKKio.] 



IMIDKS. I On., AXIC BASES.] 



IMITATIONS, in Music. [KootJE.] 



IMMATEKIALISM [MATERIALISM; BERKELEY, in Bioo, Div.] 



IMMORTALITY. [MATERIALISM.] 



