NATURAL PHILOSOPHY. 



Ill 



will be the power with which it moves. This fact, then, that the 

 force with which an electric current of a given quantity acts is the 

 same at any velocity of motion, bears no analogy to the case of steam, 

 but would indicate that the dynamic result obtainable from a given 

 electric current might be infinitely great, and so it would be, were it 

 not that the part moved always tends to induce a current in the w T ire 

 in a reversed direction ; and this inducing influence, which increases 

 with the velocity of motion, conflicts with the original current and re- 

 duces its quantity, and consequently the power of the motion and the 

 consumption of materials in the battery. Some have imagined that 

 possible alterations in the machine, or in its mode of action, would 

 avoid the evil, or even cause the indirect current to flow with the pri- 

 mary current instead of against it. The impossibility of this, though 

 not readily proved in detail, can be so at once by reference to general 

 principles. If true, it would be a creation of dynamic force, or the 

 evolving of an unlimited force from a limited one. The tendency to 

 an opposing induced current in the primary wire is involved in the 

 very principle of the system, so that no ingenuity can ever get rid of 

 the retarding influence of the induced action. The only way to over- 

 come its power, so as to prevent the primary current from falling be- 

 low a given rate or quantity, when the machine is allowed to attain 

 rapid motion, is to increase the electro-motive power of the battery, 

 the intensity (not the quantity) of the current, so that it shall be less 

 affected by the opposing induction. From a want of a clear appre- 

 hension of these principles, inventors have misapprehended the direc- 

 tion in which improvements were to be made, and much ingenuity 

 and means have been thus wasted. 



IMPROVEMENTS I.\ BATTERIES. 



PROF. H. REINSCH describes a new voltaic battery of considerable 

 power without the use of any exciting metal. A common porous cell 

 is filled with powdered coke, into which is fixed a rod of coke for con- 

 ducting the current. This porous cell is placed in a jar or glass, 

 which is then filled with coarse bruised coke, to which is also con- 

 nected a rod of the same material. The coke in the inner cell is 

 moistened with nitric acid, that in the external one with a saturated 

 solution of common salt. Conducting wires being attached to the 

 coke cylinders, a tolerably strong current is indicated. A small elec- 

 tro-magnet has thus been made to sustain half a pound, but a large 

 one was not affected. The spark and shock have been very decidedly 

 obtained from a single compound cell. London Athenawn, July. 



Carbon from Gas Retorts as the Negative Plate of the Battery. At 

 the meeting of the Royal Society on March 7, a paper was read by 

 C. L. Dresser, Esq., on "the application of carbon deposited in gas 

 retorts as the negative plate in the nitric-acid voltaic battery." In re- 

 torts used for the destructive distillation of coal to obtain the carburet- 

 ted hydrogen gas, after a certain time, a deposition of carbonaceous 

 matter takes place, which finally becomes so thick as to fill up a por- 

 tion of the retort with solid substance, and to line the whole with 



