EASTER DUBS. 



EBULLITION. 



enough M far as 8000. On the ma<hernttoal part of the calendar full 

 information will be found in Delambre's Hirtoire de I'Astronouiie 

 Modeme,' and Lalande's ' Astrooomy.' 



With regard to the faulty explanation In the act of parliament, w* find 

 that it was copied literally from the Book of Common Prayer. In this 

 work it appeared for the first time in loAz, directly after the convoca- 

 tion which mat at the Restoration of the monarchy had made the 

 alteration mentioned in Lm nor. The explanation was therefore 

 added by this convocation. Supposing the calendar moon to be spoken 

 of, it would have been correct if the second clause had been omitted. 

 For the calendar full moon i* always the fifteenth day, and it is clear 

 that - the Sunday after the fourteenth, or the next Sunday if the 

 fourteenth tall on Sunday," is the same thing as " the Sunday after the 

 fifteenth, or the fifteenth itself, if it be Sunday." Finding definitions 

 of Easter by the fifteenth, in the second of the two ways just men- 

 tioned, to nave occurred in times anterior to the Restoration, we 

 suppose that the explanation of 1662 was the result of a confusion 

 of the 



EASTER DUES. [OffMOM.] 

 EAVES. [UocsEi.] 

 EBB. [TIDES.] 



KHIONITES, a sect of Christian Jlws, which existed in Palestine 

 and other parU of the East in the 1st and 2nd centuries of our era. 

 Like the Nazarenes, with whom they have been often confounded, 

 they continued to observe the precepts and ceremonies of the Mosaic 

 law; they kept both the Sabbath and the Sunday, made their ablu- 

 tions, used unleavened bread in the celebration of the Eucharist, and, 

 moreover, abstained from eating flesh. Still they do not seem to have 

 formed a distinct sect till after the second destruction of Jerusalem by 

 Hadrian, when they became separated from the rest of the Church by 

 their dogmas as well as by their external practices. Origen, Epiphanius, 

 Eusebius, and other early fathers, distinguish two sorts of Ebionites, 

 namely, those who denied the divinity of Jesus Christ, asserting 

 that he was the son of Joseph and Mary, though endowed with a pro- 

 phetic gift ; and those who maintained that he was born of a virgin, 

 but denied his lire-existence as God. The Ebiouites in general acknow- 

 ledged only one gospel, namely, the Hebrew one, which goes by the 

 name of St. Matthew, and that one mutilated. They discarded the 

 Acts of the Apostles, and especially the Epistles of St. Paul, whom 

 they considered as an apostate from the old law. They had several 

 apocryphal books ; among others, a life of St. Peter. The earlier 

 Ebionites lived a regular life, and many of them observed celibacy, 

 which they held in great esteem. The later Ebionites became much 

 more lax in their morals. The name, of Ebiouites is said by Eusebius 

 Origen, and Ireiueus, to be derived from a Hebrew word of contempt 

 meaning " poor low people," which the Jews applied to those of their 

 countrymen who had embraced Christianity. Others have derived it 

 from a philosopher of the name of Ebion, whose existence however is 

 doubtful. Epiphanius speaks at length of the Ebionites, but he con 

 founds them with other sects, and his account cannot be trusted. The 

 Ebionites never rose into much importance, and exercised but little 

 influence on the spread of Christianity. (Mosheim, Iiutituta of Eeda 

 Ilutiiry, with nnt<i by Dr. Murdoch ; Neander, KirdiengttcMchte.) 



EBULLITION (ebaUto, to boil). Under BOILINO OF LIQUIDS were 

 given the chemical and physical aspects of ebullition. Under the 

 present head we propose to notice what is called the tpheroidtd state of 

 liijuiilii, which has of late years attracted considerable attention. 



In 1756 Leidenfrost called attention to the fact that, when water is 

 allowed to fall upon a red-hot iron plate, it does not boil, but forms 

 into drops, which roll or jump about for a considerable time. This 

 experiment lias attracted the attention at various times of such men as 

 K l.iproth, Count Rumford, Pouillet, and Dumas ; and it came to be 

 shown as a class experiment, in which case a small platinum crucibl 

 is strongly heated by means of a copious flame from the spirit-lamp 

 ami water is dropped into it from a pipette : the water does not boi 

 but the drops coalesce and roll about with considerable activity. In this 

 way about one-fourth or one-third of the crucible may be filled ; ant 

 provided the heat be well maintained, the water does not only not boi 

 but evaporates very slowly. If, however, the heat be withdrawn, th 

 water remains quiet for about half a minute, and then suddenly burnt. 

 into steam and disappears. In 1837, Mr. Tomlinson ('Mechanics 

 Magazine,' No. 703) showed that other liquids might be substitute* 

 for water in the above e\pri iment, such as pyroxilic spirit, spirits o 

 wine, sulphuric ether, and even mercury ; but the last is quickly diss 

 pated. Such fluids as come into immediate contact with the hot meta 

 such as oil of turpent ine. olive oil, and sulphuric acid, were immediate! 

 deoonipiwcd and failed to produce the effect. The same writer (' Sti 

 dent/T Manual of Natural 1'hilosophy,' 1838) also showed that man 

 dine solutions could bo used instead of water ; but the most curiov 

 result obtained by him was the use of a hot liquid surface instead o 

 a metallic one, such as a fixed oil, raised toi.the temperature of 450 o 

 600. Some care U required in this experiment : the liquid, mich : 

 water, alcohol, or ether, must be delivered from a pipette, with a stead 

 hand, directly on to the sun '..-. . ,i the hot oil; not allowed to fal 

 otherwise the liquid may sink under the surface, y itn wit 



explosive violence, and scatter about the hot oil. If, while a globu] 

 of water be rotating on the lint oil, a globule of ether be also placed <i 

 it the two drop* will coalesce and continue to rotate as one globu 



ether forming the outer surface of the drop. Tur|ventine forms a 

 lac on the hot oil, and quickly disappears by evaporation ; hut pyrox- 

 ic spirit and bisulphide of carbon form globules. Sulphuric ether 

 bo forma a globule on the surface of hot water and hot mercury, 

 ulphuric acid heated to about 400* may also be used as the heated 

 surface for ether and alcohol ; but turpentine and naphtha form disci 

 which quickly blacken the acid. Mr. Tomlirison refers to an experi- 

 uient by Perkins, in which a platinum capsule, pierced with a multitude 

 f holes like a coffee-strainer, which would not of course hold water 

 while cold, retained it when strongly heated in consequence of water 

 assuming the spheroidal state. 



The physicists who had examined this phenomenon were pretty well 

 agreed that the water, when in the globular or spheroidal state, was 

 wlow its boiling point. Of this there could, of course, be no doubt ; 

 but what the exact temperature was had not been determined, any 

 more than why the liquids, in the midst of so high a temperature, 

 should be so little influenced by it Rumford supposed it to be due 

 ' to the reflection of caloric operating on the surface of the drops of 

 water." Pouillet supposes that " the calorific rays emanating from the 

 vessel traverse the water too easily when they are very hot. ' Dumas 

 ' Chimie Appliquee aux Arts,' i. 32), while admitting the fact, thinks 

 ' it ought to caution us against the accidents which a steam-boiler is 

 iable to produce, when raised accidentally to a high temperature ; for 

 t might happen that it ceases to furnish steam, and, nevertheless, a 

 reduction of temperature would cause an explosion. Plates of fusible 

 metal are especially useful in ' preventing accidents' of this kind, since 

 hey limit the temperature that can be attained by the boiler ; for it is 

 evident that a valve would not be raised at the moment when this 

 singular phenomenon should display iUelf." 



In 1845-6 M. Boutigny exhibited some remarkable experiment* on 

 his subject before the British Association, and in several institutions 

 of the metropolis ; among others, in the laboratory of King's College, 

 where the writer had an opportunity of seeing them. The most 

 remarkable effect was the freezing of water in a red- or white -hot 

 crucible, for which purpose advantage was taken of the low boiling- 

 mint (that is, 140 Fahr.) of liquid sulphurous acid. This assumes 

 hi' spheroidal state a little below 14; and if water be dropped into 

 ,he crucible, it immediately falls considerably below its freezing-point, 

 and a lump of solid ice can be turned out of the glowing vessel 

 .nto the hand. Faraday has even carried the matter further, by 

 freezing mercury under similar circumstances, substituting for the 

 sulphurous acid a solution of solid carbonic acid in ether. By means 

 of this mixture, a degree of cold has been obtained ' equal to about 

 166 ; and as mercury freezes at 39, we can understand how the 

 mixture will assume the spheroidal state in the red-hot crucible, and 

 mercury be readily frozen. Boutigny also placed iodine on an ignited 

 platinum capsule, when it melted, formed a spheroidal black-looking 

 mass, which rolled about and gave off but little vapour. But when 

 the source of heat was withdrawn, an abundant evolution of vi"!> t 

 coloured fumes took place. A thick cylinder of silver was heated to 

 redness, and lowered by means of a wire into a glass of water, where it 

 quietly remained for a considerable time. But perhaps the most 

 remarkable result was the impunity with which M. Boutigny passed 

 his hand backwards and forwards through a stream of cast iron as it 

 issued from the furnace, thus showing that the old ordeal by fire was 

 not so formidable a trial as would at first sight appear. The above 

 phenomena admit of explanation : First, on the fact that, wli 

 the liquids are thrown upon strongly-heated surfaces, a portion of the 

 liquid is immediately converted into vapour, upon which the globule 

 rests as on a cushion. Now as this vapour is a bad conductor of heat, 

 it shields the globule from the conducting powers of the heated - 

 In the second place, the evaporation from the surface of the globule. 

 carries off the heat as fast as it arrives, and thus maintains the globule 

 at a temperature below that of its boiling-point. The spheroidal form 

 of the drop is a joint effect of gravity and cohesion among the lluM 

 particles. There must also be taken into account the repulsive 

 exerted by heat under the circumstances. So necessary is the condition 

 that the liquid in the spheroidal state shall be below boiling, that if a 

 liquid actually in the state of ebullition be introduced into the roil -hot. 

 crucible, its temperature sinks from 5 to 7 below its l>i>iling-]Hiiiit. 



According to Boutigny, all liquids are capable of assuming this state 

 but in all cases the heated surface must liear a r. rt.iin relation to tho 

 boiling-ixiint of the liquid: if the latter be low, the former niunt. !" 

 comparatively low also. The required temperature depends partly < >u 

 the conducting power of the plate, an.l partly on the latent heat of 

 the vapour : as this is small, the heat of the plate may approximate 

 more nearly to the boiling-point of the liquid. The lowest heat of the 

 plate required to throw water into the xphuroidal state is said to be 

 840 Fahr. ; alcohol, 278; ether, 142. The temperature of eaeh 

 liquid in the spheroidal state i> Kiipixwed to be as definite as its 

 boiling-point. Boutigny gives 205'7 Kahr. as the temperature of the 

 M lal state of water, 107'.' !'" tli.it of aleohol. <i;i-(i j for that of 

 i-tliiT. and I ;H for that of tsnlphurons acid. The spheroidal state may 

 lie pi. dneeil in vacuo. In the e\peiimeiit in which the moist hand in 

 made to cut a stream of molten inm, the moisture of the hand f. am-' 

 the cushion of steam which prevents the metal from coming in contact 

 with the skin. 

 An ingenious application of the spheroidal condition of liquid , i 



