234 Analyses of Books. [March 



protochloride of tin, chloride of silver, but water acidulated with 

 sulphuric acid, solution of muriatic acid, solution of sulphate of 

 soda, fused nitre , and the fused chloride and iodide of lead, were 

 not affected by a single pair of plates excited only by dilute sulphuric 

 acid. All these substances were, however, readily decomposed by 

 adding a little nitric acid to the dilute sulphuric acid. It is suffi- 

 ciently obvious that the addition of the nitric acid operated by in- 

 creasing the intensity or power of the current. 



By the reference which is thus made of the intensity of the electric 

 current to the intensity of the chemical action, the conclusion is 

 drawn that by using bodies such as fused chlorides, salts, &c, which 

 may act upon the metals with different degrees of force, effects 

 would be obtained due to different intensities, which would serve to 

 assist in the construction of a scale, so as to supply the means of 

 determining relative degrees of intensity accurately in future re- 

 searches. The bodies which have been examined are decomposed in 

 the following order, the first being disunited by the current of the 

 lowest intensity. Iodide of potassium (solution.) Chloride of silver 

 (fused.) Protochloride of tin (fused.) Chloride of lead (fused.) 

 Iodide of lead (fused.) Muriatic acid (solution.) Water acidulated 

 with sulphuric acid. 



Another proof that metallic contact has nothing to do with the 

 production of electricity, and that electricity is only another mode 

 of the exertion of chemical forces, is the production of the electric 

 spark before the metals are brought in contact, and by the influence 

 of pure chemical agency in an experiment where the spark is obtained 

 by placing in contact a plate of zinc and a plate of copper, and plung- 

 ing them in dilute sulphuric acid. 



The principles which the author endeavours to establish in the 

 course of his researches are, that the electricity of the voltaic pile is 

 not dependent either in its origin or its continuance to the contact of 

 the metals with each other. It is entirely due to chemical action, 

 and is proportionate in its intensity to the intensity of the affinities 

 concerned in its production, and in its quantity to the quantity of 

 matter which has been chemically active during its evolution. The 

 production of electricity is a case of chemical action, while electric de- 

 composition is simply a preponderance of one set of chemical affinities 

 over another set which are less powerful. The scource of the elec- 

 tricity exists in the chemical action which takes place directly between 

 the metal and the body with which it combines, and not in the 

 subsequent action of the substance so produced with the acid present. 

 Thus if zinc, platinum, and muriatic acid are employed, the elec- 

 tricity depends upon the affinity of the zinc for the chlorine, and 

 circulates in proportion to the number of atoms of the zinc and 

 chlorine which unite. But for this direct action upon the metal 

 itself, it is essential that the oxygen or other body be in the state of 

 combination, and limited to the state of an electrolyte, that is a 

 body which is decomposed when the electric current is transmitted 

 through it. 



Some bodies there are which are capable of exerting chemical 

 action upon the metals which arc not electrolytic ; but these must 



