98 Sir H. Davy on the Relations 



kind, tlie well known phaenomena of the development of 

 chlorine and oxygen and acid matter at the positive, and hy- 

 drogen, alkaline matter, &c. at the negative pole, takes place. 



Acid and alkaline matters, when perfeclly dry and non- 

 conducting, become on contact negative and positive ; as I 

 have shown is the case with oxalic acid and lime; but this 

 effect is similar to that of glass and silk, and the result is a 

 common electi'icity of tension. And when acids and alkalies 

 combine, their union being apparently the result of the same 

 attractive powers acting on the particles which would pro- 

 duce their electrical relations as masses, they exhibit no phjE- 

 nomena of electro-motion ; and such phaenomena, when they 

 occur in combinations in which acids and alkalies unite, al- 

 ways depend upon the contact of the metal with the acid and 

 alkaline matter, change of temperature, evaporation, &c. and 

 never on the combination of the acid and alkali. 



As a different opinion has been lately started, on high au- 

 thority*, I shall give the jiroofs of the truth of this my early 

 view, which appear to me of the strictest demonstrative nature. 



A solution of niti'e, which is a substance neutral to the con- 

 tact of noble metals, was introduced into a glass cup contain- 

 ing a plate of platinum connected with the multiplier ; pure 

 concentrated nitric acid was placed in another cup, in which 

 there was another plate of platinum joined to the other wire 

 of the multiplier, and the connexion was made by a piece of 

 asbestus wetted in a solution of niti'e. At the moment of 

 contact, the needle indicated a strong electrical action, nega- 

 tive on the plate plunged in the acid, and which occasioned a 

 permanent deviation of about 60°. 



This arrangement was removed from the mul'dplier, and 

 another substituted for it, in which strong solution of potassa 

 occupied the place of the nitric acid, being in contact with 

 platinum in one cup, and solution of nitre in the other, with 

 the same communications. The deviation was now much 

 weaker, about 10 degreesj and the platinum in the .solution of 

 potassa was |)Ositive. 



The nitric acid and the solution of potassa were now con- 

 nected in the arrangement by a piece of clean asbestus, mois- 

 tened in a concentrated solution of nitre; the deviation of the 

 needle was to about 65°. In this instance there was no che- 

 mical action of the fluids on each other; for they had no ten- 

 dency to mix rapidly with the solution of nitre, which being 

 of less specific gravity than either of the other solutions, re- 

 mained in the asbestus ; and there was no effect beyond that 

 of the metallic contact of the platinum with acid and alkali. 



• That ofM. Becquerel. 

 hi; A Apiece 



