258 



♦ KNOWLEDGE ♦ 



[May I, 1883. 



olofjantly, perhaps, by showing that the globule would not 

 pass an electric current. 



It was also shown that solids, in liquefying in a hot 

 metallic capsule, pass into the spheroidal state, as in the 

 case of iodine. So also liquids become spheroidal if dropped 

 upon a hot plate contained in an exhausted receiver. 



It had long been known in the iron forgo that a highly- 

 heated bar of iron or of steel, plunged suddenly into water, 

 will continue so for some short time, without perceptibly 

 alTecting or being affected by the water. Boutigny shewed 

 an eflTcct of this kind by raising to a red heat a solid cylin- 

 der of silver, and lowering it into a beaker of water; 

 although it must lie admitted that when I saw him attempt 

 this experiment a second time, the beaker suddenly ex- 

 })loded. A copper vessel was lieated by means of a spirit- 

 lauip, water was dropped into it, and the neck tightly 

 corked. On withdrawing the heat, the water came into 

 contact with the hot metal, flashed into steam, and drove 

 out the cork with explosive violence. Boutigny imagines 

 that some steam-boiler explosions may thus be produced. 

 If, for example, during dinner-hour the water shall have 

 entirely evaporated, the bottom of the boiler may become 

 red hot, so that on readmitting water it may pass into the 

 spheroidal state, and coming in contact with the heated 

 metal may flash into steam, beyond the capacity of the 

 valve to remove it before an explosion takes place. 



Another wonderful illustration of the spheroidal state 

 was introduced by Boutigny, and repeated by Professor 

 Williamson at one of the meetings of the British Associa- 

 tion, viz., passing the moist hand to and fro through a 

 stream of molten iron from a cupola furnace. It has been 

 supposed that some of the persons subjected to the fiery 

 ordeal of the Middle Ages may have owed their safety to 

 some such principle. At the Polytechnic Institution, 

 some years ago, a boy with naked feet stepped rapidly over 

 pieces of iron hot enough to explode gunpowder. I was 

 informed at the time that his feet had been wetted with a 

 solution of sal-ammoniac. There is also a well-known 

 conjuring trick, in which a man licks a bar of red-hot iron, 

 the moisture of the tongue preventing any ill-effects. 

 Here, too, we may refer to an old observation by Macquer, 

 that gold spins when melted into a globule, and that minute 

 fragments of grit on its surface are powerfully repelled. 

 When the metal is fused by the action of a large lens, fine 

 powder on the surface is dispersed, as if by a powerful 

 blast of the breath. 



Boutigny adopts the theory of a repulsive force between 

 the hot surface and the liquid, or that the tension of the 

 vapour keeps the globule at a distance, so that the liquid 

 is not heated by contact, but only by radiation, water 

 being diathermanous, the rays of heat pass through 

 without raising its temperature. It may also be added 

 that the vapour is a bad conductor of heat, and that 

 evaporation from the surface of the globule carries off' the 

 heat as it arrives. 



!Mr. Perkins, the engineer, also showed that water can 

 be dropped upon a red-hot metal colander without passing 

 through ; and even that water will not pass through a 

 red-hot metal pipe. 



In connection with the spheroidal state, Eisenlohr re- 

 marks that if boiling water be covered with lycopodium, 

 the finger can be passed into it with impunity ; but this, I 

 imagine, arises from the fact that the powder prevents the 

 finger from being wetted. 



With respect to the spheroidal state of liquids at common 

 temperatures, I have had abundant opportunities of 

 observing it in the course of my researches on the Cohesion 

 Figures of Liquids. I may briefly refer to some re- 

 sults obtained by me in 18G;!. Essential oils were 



used, and it was found that the duration of the spheroidal 

 state formed an approximative method of determining 

 their purity. Three glass vessels were used, each 

 about 2.\ in. in diameter ; they were nearly filled with 

 water, on which a film was formed from turpentine pro- 

 cured from a colour-shop. The mean of twenty-four 

 experiments gave 15^- seconds for each drop, placed on the 

 film, and assuming the spheroidal state. The turpentine 

 was next distilled ofi" caustic potash, and a similar .series 

 of observations made with the fresh distillate, when the 

 mean duration of the globule in the spheroidal state was 

 now 36^ seconds, or about 7 to 3. 



The spheroid, whether rolling about or stationary, dis- 

 plays active motion among its particles. If a little lyco- 

 podium powder be shaken over the globule, and this rude 

 treatment do not cause it to break up, the powder will 

 display the convective currents of the gloV>ule, streaming 

 rapidly down its outer surface, and ascending liy the central 

 vertical axis, to separate again at the top, and sti-eam over 

 the surface again to the bottom. 



An essential oil does not readily assume the spheroidal 

 state on the film of another oil, and a drop of a fatty oil 

 does not readily become spheroidal on a film of a fatty 

 oil ; but by raising the temperature of the surface, globules 

 of various liquids can be readily formed, as already noticed. 



In Professor Tyndall's work on "Sound" (1867), he de- 

 scribes (p. 154) a method of producing some of Chladni's 

 figures by drawing a fiddle-bow over the edge of a glass 

 goblet containing ether or alcohol ; and he gives to M. 

 Melde the credit of "this beautiful experiment." The 

 experiment is really due to me, and v.as described with a 

 figure in Thomson's " Records of General Science," vol. iv., 

 p. 14, published in July, 1836. It was also shown that 

 fi.xed oils do not show the usual beautiful crispating figures 

 under the influence of the fiddle-bow, but do so readily 

 when heated. 



In the appendix to my " Cyclopoedia," published in 

 1866, a number of spheroidal figures are gi^•en in the 

 form of a four, six, or eight-rayed star formed by pouring 

 turpentine on water at about 150" F. in a goblet, so as to 

 form a thin layer, and drawing the fiddle-bow against the 

 edge. The curved spaces outside the circle represent 

 portions of liquid often beautifully reticulated, that ascend 

 the glass in a vertical direction while the crispating fans 

 are on the surface of the liquid, and the spheroidal stars in 

 the centre, their rays pointing to nodal lines. 



A BR.\ss cannon, 6 ft. long, has been found by an agri- 

 culturist, whilst ploughing, at Coorum, near Soopa, in the 

 Bhimthudy talooka. This cannon, it is said, was manufac- 

 tured by Michael Burgerhays, and is d.ated 1640. 



The Society of German Railway Administration has 

 resolved upon opening every three years prize competitions 

 of a total amount of 30,000 marks, for important inven- 

 tions in railway matters, namely : — (1) For inventions and 

 improvements in the construction of railroads — 1st prize, 

 7,500 marks ; 2nd prize, 3,000 marks ; 3rd prize, 1,500 

 marks. (2) For ditto in the means of transportation, and 

 their use — prizes the same as at 1. (3) For ditto respect- 

 ing the general administration of railroads, railroad statis- 

 tics, and prominent subjects of railroad literature — 1st 

 prize, 3,000 marks ; 2nd and 3rd prizes, 1,500 marks each. 

 The award of a prize is not to prevent the inventor from 

 patenting his in\entiou or his sale of the patent. The first 

 competition of this kind has been made public, and applica- 

 tions are to be sent in between Jan. 1 and July 15, 1884, 

 to the managing director of the society at Berlin. 



