ELECTRICITY. 



405 



bv insensible gradations into the latter. The 

 form of .the negative spark differed greatly from 

 that of the positive, being destitute of rays, 

 generally circular in shape, and often made up 

 of a number of minute circles placed without 

 symmetry. For like distances it was also larger 

 than the positive, and never nearly so well de- 

 fined. Moreover, there is a general resemblance 

 between the positive and negative figures as 

 thus obtained, and the figures of the correspond- 

 ing sorts obtained by Lichtenberg and Riess by 

 ._' the sparks to a surface sprinkled with 

 powdered sulphur and red lead, and known as 

 ' Lichtenberg's figures." " Aruer. Jour, of Sci- 

 ence," March, 1862. 



Production of Vibrations and Musical Sounds 

 ly Electrolysis. If a large quantity of electri- 

 city be made to pass through a suitable good 

 conducting electrolyte into a small surface of 

 pure mercury, especially when the latter is dis- 

 posed in a narrow band or ring, strong vibra- 

 tions will occur, the surface of the mercury 

 being thrown up into numerous crispations or 

 minute ridges running in a radial direction, 

 this appearance being often accompanied with 

 definite musical sounds,- and which can some- 

 times be heard to a distance of 50 feet. The 

 best electrolyte or liquid employed to conduct 

 the current (while undergoing decomposition 

 by its action), is formed by dissolving 10 grs. 

 of cyanide of mercury and 100 grs. of hydrate 

 of potash, in 2J oz. of aqueous hydrocyanic 

 acid, containing .05 of the anhydrous acid. The 

 vibrations and sounds occur only at the surface 

 of the mercury, which serves as the electrode. 

 The only liquids giving the phonetic vibrations 

 were solutions of alkaline cyanides, containing 

 dissolved mercury (in combination), and these 

 only when the electrodes, or at least the cath- 

 ode (positive pole) was of mercury. The vi- 

 brations and sounds vary considerably accord- 

 ing to the size and number of the voltaic ele- 

 ments. With a few cups only in the battery 

 and the plates of large size, the vibrations were 

 rapid and the tone high; with many pairs of 

 small plates, the vibrations were less frequent 

 and the tone low. The most suitable number 

 of elements appeared to be 2 of Grove ? s, or 5 

 of Smee's battery. By interposing in the cir- 

 cuit made a coil of stout copper wire, the. 

 sounds became more bass, still more so upon 

 thrusting an iron coil suddenly within this; 

 but if, in either case, a secondary coil with its 

 ends united were made to surround the former, 

 the sound returned to the higher pitch and pre- 

 served it so long as the outermost coil remained 

 in place. A strong electro-magnet placed in 

 various positions in the neighborhood of the 

 vibrations had no influence in the way of chang- 

 ing or arresting them. The phenomena were 

 readily produced by connecting with the posi- 

 tive pole of the battery a circular pool of mer- 

 cury 1 to 3 inches in diameter, and surrounding 

 this with a ring of the same metal about \ in. 

 wide, connected with the negative pole; the 

 liquid metal being contained in suitable glass 



or gutta percha vessels, and covered with the 

 solution to the depth of half an inch. Mr. G. 

 Gore, by whom these investigations have been 

 conducted, regards the vibrations as having an. 

 electro-chemical origin, and as resulting from 

 an attraction between the mercury of the ne- 

 gative electrode and the mercury of the elec- 

 trolyte. 



- Experiments in Electro-Magnetism. M. 

 Leroux, of the Polytechnic School, Paris, hav- 

 ing a platinum wire about ^^ of an inch in 

 diameter, and 7 inches or more in length, ren- 

 dered incandescent by being made part of an 

 electrical circuit, presented the wire in this 

 state and properly flexible to the poles of a 

 powerful magnet or electro-magnet : the wire 

 assumed a series of configurations, depending 

 on the direction of the current and whether 

 the line joining its extremities has a position 

 axial or equatorial with reference to the mag- 

 net. Such a wire was attracted by a mass of 

 iron, especially if the latter presented a large 

 surface, a counterpart of Arago's experiment 

 that a wire traversed by a current attracts iron 

 filings. Leroux also showed how a fine con- 

 junctive wire could be made to coil itself spon- 

 taneously around the pole of a magnet. Hav- 

 ing fixed" upon one of the poles of a horse-shoe 

 magnet an armature of soft iron, about 4 inches 

 in length, turned and polished, he attached to 

 this armature the extremity of a silver wire, 

 holding the other extremity in his hand, but so 

 loosely that the wire could constantly obey the 

 forces which solicited it. When this wire was 

 then traversed by a current, it coiled itself 

 around the armature, and there formed a helix 

 wound in a direction opposite to that which 

 would be required to give to the armature the 

 same magnetism it already possessed. This ex- 

 periment is more conveniently performed by 

 having the wire at first coiled on a small me- 

 tallic bobbin suspended above the magnet ; and 

 the more constant the length of wire traversed 

 by the current, the less is the risk of burning 

 it. Thus is found a new kind of motion ob- 

 tained by the action of the pile. To prevent 

 the undue acceleration of this motion, a smaller 

 cylinder may be fixed on the axis of the bob- 

 bin, from which a small weight at the end of a 

 silk thread draws in the direction opposite to 

 that given to the bobbin by the uncoiling wire. 

 For these experiments a current of about 10 

 Bunsen's elements was employed. 



Electricity Developed during Evaporation and 

 Effervescence.. Prof. Tait and Mr. Wanklyn 

 have, by use of the extremely sensitive and ac- 

 curate divided ring electrometer of Prof. Thom- 

 son, investigated the phenomenon of develop- 

 ment of electricity by evaporation of certain 

 liquids, during the few moments in which on 

 quitting the " spheroidal state 1 ' in a heated cap- 

 sule or dish, and coming again in contact with 

 its surface, they emit the well-known " fizzing 1 ' 

 sound attending their rapid evaporation at that 

 period. By conducting wires suitably arranged, 

 in course of which the electrometer was placed, 



