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DISSYLLABLE, among grammarians a word consisting onlyof two syllables; such are nature, science, &c.

DIS i AIT', an instrument about which liax is 4ied in order tobe spun.

DIS TANCE, in general, an interval between two things, eitherwith regard to time or place. See Metaphysics.

Distances, Accessible, in geometry, are such as may bemeasured bv thecham, Sec. See Chain, Theodolite .

Distances, Inaccessible, are such as cannot be measured bythe chain, Sec. bv reason of some river, or the like, w hich obstructsour passing from one object to another. See Geometry and'Trigonometry-

Distance, in navigation, the number of minutes or leagues aship has sailed from any given place or point. See Navigationami Mensuration.

Distance, in astronomy. The distance of the sun, planets,and comets, is only found from their parallax, as it cannot befound either by eclip-es or their dilTerem piiases : for from thetheory of the motions of the earth arid planets we know, at anytime, the proportion of the distances of the sun and plaints Iromus; and the horizontal parallaxes are in a reciprocal proportion tothese distances. See Astronomy.

Distance, Curtate, in astronomy, is the distance of the pla-net’s place, reduced to the el liptic , from the sun.

Distance of the Bastions , in fortification, is the side of theexterior polygon.

Distance of the Eye , in peispective, is a line drawn fromthe eve to the centre of the picture. See Perspective.

DISTEMPER is frequently used in the same sense as disease,but is particularly applicable to cattle. This term implies a spe-cies of contagious fever, attended with an inflammation, which issucceeded by a gangrene in the lungs, liver, or intestines. It isalways preceded by a shivering and trembling of the limbs, whichare followed by various febrile symptoms, such as difficulty ofbreathing, a sinking in the flanks, and a dryness on the tongue,together with a loathing of the usual food and drink, great heavi-ness and debility. Animals affected with the distemper, frequentlyshed tears; their eyes appear sometimes sparkling and inflamed,but at intervals dull and languid. Their food remains crude inthe stomach for several days after it has been eaten, from theirinability to digest it. This contagion spread most rapidly in theearly part, ami about the middle of last century, over several pro-vinces in France , whence it reached this country, and destroyedgreat numbers of cattle. Various causes of this malady have beenassigned, but that most generally admitted, is the turning of cat-tle into rank grass, especially after heavy and frequent showers.Different remedies were then adopted, the best of which appearsto be bleeding the infected animal in the earlier stages of the dis-order; ami the internal use of the Peruvian hark and red wine;or, if the-e should fail to procure relief, a mixture of that drug andof burdock, about half an ounce of each, pulverized, mav begiven twice nightly, for two or three succeeding nights, in warmwater, which will seldom fail of effecting a cure.

Distemper, in painting, a term used for the working up of co-lours with something besides water or oil. If the colours are pre-pared with water, that kind of painting is called limning; and ifwith oil, is called painting in oil, and simply painting, ll the co-lours are mixed with size, whites of eggs, or any such proper glu-tinous or unctuous matter, and not wi h oil, then they say it is donein distemper.

Distension, [ditUnsio, Lat.] among ancient musicians, is usedin a synonymous sense with interval, bee Interval.

DIS'l It 11, [3‘eix”>3 a couplet of verges making a completesense. 'Thus hexameter and pentameter verses are disposed indislichs.

DISTICUIASIS, in surgery, a disease of the eye-lids, whenunder the ordinary eye-lashes there grows another extraordi-nary row of hair, wh.ch frequently eradicates the former, andpricking the membrane of the eye, excites pain, and brings ona deflexion.

DIS'I I LLATION, a chemical process employed to separateliquids Iron ) tho‘e parts of hod.es whic h are more fixed, whethersolid or liquid ; the process by which the sol.d parts of bodies areseparated is called sublimation. See Chemistry. The appara'ux !employed for disliilalton are of several varieties, suited to the nature j

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j of the volatile body. That employed for the distillation of water,

| alcohol, and essential oils, is called a still. It-is chiefly made ofcopper, and ought to be so < onstrueted, that as great an evapora-l>le surface as possible may be exposed. The vapour which comesfrom the still, is condensed by causing it to pass through a spirallube, fitted into the inside of a tub, which is tilled with cold wa-ter, and so contrived, that the product of the distillation shallhave no commuuic ilion w ilh the external water. 'This tub, whichis called a worm tub, should be supplied with cold water at thebottom, while the warm water, caused by the condensation of thevapour, should be made to run off at the lop. 'The apparatus em-ployed lor distilling bodies more easily condensable, consist oftwo pails, one called the retort, containing the substance to bedistilled, and the other the receiver, because it receives the sub-stance raised from the retort. In the distillation of bodies whichatlorcl permanent gasses as well as condensable matters, in additionto the receiver, a number of connected vessels are employed, con-stituting what, from its invention is called a Woulfc’s apparatus, inwhich, what is not condensed, or absorb d in the first bottle,passt-s forward to the second, and so on to the third and fourth,till at length the absolutely incondensable part is received into avessel called a gasometer. Before the invention of this apparatus,this kind of distillation was attended with great danger, both tothe apparatus and the operator; the receiver being very liable toburst, and the fumes being intolerably suffocating. Both theseinconvenieneies are completely obviated bv the invention of the\V null’s apparatus. See Chemistry. Sometimes an apparatuscalled an alembic is used for distillation; it is generally of glass,and is used for experiments in the small way ; it consists of a bot-tle holding the substame to be distilled, having a dome-like head,furnished with a channel to convey the condensed vapour. Thereare various modes of applying heat in distillation, depending uponthe nature of the apparatus employed, as well as upon the sub-stance to be distilled. The common still, which is of metal,is immediately exposed to the naked fire, since from its tenacity,and its property of conducting heat with facility, it is not liable tocrack, which is not the case with glass and earthenware. If thevessel holding the substance to he distilled, be of the latter kind,it is essential to apply the heat very gradually and uniformly, andafter the process, to suffer it to cool in a similar manner. This iseffected in d iVerent ways; the most common of which is the sand-bath. In experiments in the small way, the lamp will answerevery purpose of the sand-bath, as the sliding rest containing theretort, admits of its being placed at any given distance from theflame. In addition to this, the Argand lamp can be adjusted bythe rack, to almost any degree of intensity below its maximum.Another method of defending the retort from the too rapid effectof the heat, consists in coating the outside w ith a mixture of horse-dung and clay, or loam. When a limited degree of heat is re-quired in distillation, recourse is had to a bath of some liquid,whose boiling point will give the degree ot heat required, such aswater, oil, or mercury. If the different bodies subjected to dis-tillation had no chemical affinity for each other, it is probable thateach substance would put on its elastic form, only at that tempe-rature at which it would, in a separate state, be converted into va-pour. But we frequently find, that one volatile substance willcarry along with it other bodies of considerable fixity. From theaffinity which water has to air, we observe the evaporation of theformer to take place at all temperatures below its boiling point ; andthough it lias been thought that water might he heed Irom salinematter by distill..lion, it is found hv experiment, that several saltsare carried over along with the vapour of the water, which intheir dry state would undergo decomposition before they wouldlie induced to assume the elastic form. Hence water, by thecomim n mode ot distillation, cannot he rendered pure. From thecircumstance, that the air is capable of raising water and other li-quids at a low temperature, we are enabled to peiform the distil-lation of stub liquids, by making the slightest degree of differenceof temperature between the retort am. the feceivrr. Water andalcohol may be obtained perfectly pure, by pi -1 ing the retort in thetemperature ot 100°,and the receiver in tluitnt50°»l Farcii licit’s scale.The salts most liable to ri e with water in distillaiiou are carbonateammonia, muriatesof lime and magnesia, and nitrate of soda. Indeedthis tendency appears to he directly, as the solubility of the salt orrather as its deliquescent property, which is as ils affinity for wafer.

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