570 Intelligence and Miscellaneous Articles. 



most series there are other fossils which occur in the Bannisdale 

 Slates and Kirby-Moor Flags, thus giving further indications of a 

 northward migration. 



16. "On some Superficial Deposits in the Neighbourhood of 

 Evesham." By the Rev. A. H. Winnington Ingram, M.A., F.G.S. 



17. "Descriptions of Palaeozoic Corals from Northern Queens- 

 land, with Observations on the Genus Stenopora." By Prof- H. A. 

 Nicholson, M.D., D.Sc, F.G.S., and E. Etheridge, Jun., F.G.S. 



LXIX. Intelligence and Miscellaneous Articles. 



ON A PILE WITH CHLORIDE OF LIME. BY ALF. NIAUDET. 

 ^THE pile which I submit to the Academy has for its positive elec- 

 ■*■ trode a plate of zinc, and for its negative electrode a block of carbon 

 surrounded by carbon fragments. The zinc is immersed in a solu- 

 tion of chloride of sodium, the carbon in chloride of lime in a porous 

 vessel of porcelaine degourdie or of parchment paper. Chloride of 

 lime is, as is known, a mixture of lime and hvpochlorous acid ; this 

 substance appears very suitable for depolarizing the carbon elec- 

 trode, since both of its elements can combine with hydrogen to form 

 water and hydrochloric acid. This acid attacks the zinc and forms 

 chloride of zinc, or the lime and forms chloride of calcium ; these 

 two salts are highly soluble and are very good conductors. 



It will be seen that all the combinations produced are soluble ; 

 moreover, if salts be formed, or substances of complex composition, 

 as happens in nearly all piles, they are soluble, as experiments 

 dating from three years since have shown me. 



Zinc in presence of chloride of lime is not attacked appreciably : 

 consequently the piles in which they are associated can be left for 

 an indefinite time at rest without wear ; the action commences only 

 when the circuit is closed. This property is, as is known, of capital 

 importance for a great number of applications. 



"We must also justify the employment of sea-salt : its being less 

 expensive is not the only advantage it presents ; it is one of the 

 most conductive liquids known. Besides, we have tried other 

 chlorides — particularly sal-ammoniac and chloride of lime, — and 

 other liquids, hydrochloric and sulphuric acids for instance : they 

 have all given less satisfactory results and less powerful electromo- 

 tive forces than sea-salt. The reasons of these inferiorities are 

 doubtless various ; as regards sulphuric acid, they appear to depend 

 on the formation of insoluble sulphate of lime, which interferes 

 with the ulterior reactions. 



The electromotive force at the commencement was found to be 

 above 1*6 volt ; it was more than 1*5 after the pile had been left 

 for several months. 



The depolarization produced by the chloride of lime is not com- 

 plete as in the pile with sulphate of copper : if the current be made 

 to pass continuously with a weak external resistance, the electro- 

 motive force diminishes, as happens with almost all piles. But that 

 force resumes its first value in a short time, as seen in the follow- 

 ing experiment : — The" current-circuit of one element was closed 

 during 40 minutes, with an external resistance of 1 ohm ; the elec- 



