TRANSACTIONS OF THE SECTIONS. 53 



Tn oi'der to produce a large surface within a small space, and with little material, 

 positive and negative wives are coiled round a small lengthy piece of wood in such a 

 manner that thej' run parallel to each other at very small distances hut without in- 

 termediate contact. At each extremity of the wooden core the end of one of the 

 wires is bent into a gilt eye (the other end being fixed in the wood), so that at one 

 extremity of the wood, the eye from the positive wire at the other extremity, that 

 from the negative wire projects beyond the core ; the whole forming the metallic 

 part of a galvanic element, with space between the wires for the fluid. A number of 

 such elements linked together on the principle of the voltaic pile, therefore, con- 

 stitutes the metallic part and arrangement of a battery, permanently connected, flexible 

 in all directions, of considerable surface (quantity), in pi'oportion to its size, and 

 of an intensity only limited by the mtmber of elements employed. 



When this chain is immersed for a moment into any dilute acid, the capillary 

 attraction between the parallel wires and the absorption of the wooden core, on the 

 removal of the chain from the liquid, retains a quantity of fluid sufficient to excite 

 the battery from one to two hours. To account for the surprising power and con- 

 stancy of these small batteries, it must be considered — 



First. That the acting surface is very considerable in proportion to the substance 

 of the metal, the wires being excited on the whole of their surface. 



Secondly. That the resistance of the fluid to conduction of the electric current is 

 reduced to a minimum, the layer of fluid between all parts of the wires being very thin. 



Thirdly. That no adherence of gas to the negative wire takes place, owing to the 

 facility afibrded for its escape by the thinness of the layer of fluid interposed ; for the 

 same reason the counter polarization of the negative plate by the deposition of me- 

 tallic zinc upon it (which is a necessary consequence of the action of any other single 

 fluid circle) is effectually prevented. 



For experiments in which an intermitting current is required, M. Pulvermacher 

 has contrived two instruments : — 



First. The interrupting cylinder, consisting of a spiral spring fixed in a small glass 

 tube so as to produce by every motion of the instrument an intermittent connexion 

 between two metallic hooks at the extremities of the tube ; this is principally used 

 for physiological and medical effects, as the shock given to a person holding the chain 

 communicates constant and continuous vibration to the instrument sufficient to prO" 

 duce the requisite intermission in the connexion. 



Second. The portable interrupting clock-work (size five cubic inches), by which the 

 current is made more rapidly and regularly intermittent. 



The following are some of the properties and uses noticeable in this form of battery:— - 

 A galvanic battery of 120 elements, permanently connected and therefore ready for 

 instantaneous use, only occupies the space of an ordinary pocket-book. In the labo- 

 ratory it will form, no doubt, a very useful instrument of research, when it is borne 

 in mind that the read)', and, in some cases, instantaneous application of electricity 

 (even were it attained onlj- with instruments of small power) is one of the greatest 

 desiderata of the present day and in the present state of science ; the general useful- 

 ness of this instrnment will then immediately become apparent. 



With the application of it to these ends then only in view, the follovcing points 

 of interest present themselves, viz. that it is a good and instantaneous means 

 of testing solutions in which either acids or bases are suspected to exist in small 

 quantities ; that it affords a ready and almost instantaneous means of coating metallic 

 and other conducting surfaces with thin films of metals, either in the most minute 

 state of division, in a crystalline manner, or in a reguline form ; that as the intensity 

 of this arrangement may be said to be unlimited, it decomposes the oils and hydro- 

 carbons with facility, thus opening a wide field of research. 



Eight elements charged with distilled water decompose distilled water, and other 

 most unequivocal proofs of enormous power in this respect are given : it is also capable 

 of giving all the results of common statical electricity, still combining the admirable 

 continuity of action of an hydro-electric arrangement, with the sharp effects of that 

 derived from the frictional machine. 



The heating effects of this arrangement will not be without their uses, both in 

 exploding gases and other materials. It has also been suggested, that for the easy 

 communication, by electricity, from a train on the line to any station, or at by-stations 



