of Electrical a?id Chemical Changes. 195 



valent masses, it would be natural to refer the action of the 

 poles to the repulsions of the substances combined with ex- 

 cess of one fluid, and the attractions of these united to the 

 excess of the other fluid; and a history of the pha^nomena, 

 not unsatisfactory to the reason, might in this way be made 

 out ; but as it is jjossible likewise to take an entirely different 

 view of the subject, on the idea of the dependence of the re- 

 sults upon the primary attractive powers of the parts of the 

 combination on a single subtile fluid, I shall not enter into 

 any discussion upon this obscure part of theory, but I shall 

 endeavour to clear the way for elucidations of it by statins 

 some expernnentai results. 



Some solution of nitrate of potassa was introduced into a 

 glass basin of six inches in diameter, and large slips of paper, 

 tinged with litmus and turmeric, were placed below the fluid, 

 and connected with two pieces of foil of platinum ; so that 

 the indications of the formation of acid and alkali, in any part 

 of the basin, by electricity, would be instant and distinct. 

 The two pieces of foil were now connected with the poles of 

 a voltaic battery : it was found that the alkali was developed 

 only at the point or immediate surface of the negative plati- 

 num, and the acid in the same manner at tiie surface of the 

 positive platinum ; and they then gradually diff'used them- 

 selves through the fluid in a circle round the conductors, and 

 there was no appearance of any repulsions or attractions of 

 the menstrua in the line of the circuit. 



In various repetitions of this experiment the same result was 

 obtained; the alkaline and acid matters were influenced in 

 their direction only by currents produced by the disengaged 

 oxygen or hydrogen, or the inclination of the vessel; in short, 

 by mechanical causes only ; and the same effects were pro- 

 duced on the test papers, as if a spherical piece of acid and 

 an amalgam of potassium had been introduced in the places 

 of the two poles, 



Mr. Herschel has shown, by some elaborate and ingenious 

 experiments in the last Bakerian Lecture, that an amalgam 

 of potassium, containing so minute a portion as some hundred 

 thousand ))arts of its weight is strongly attracted so as to oc- 

 casion violent mechanical motion, by the negative pole in a 

 voltaic arrangement: and if it be supposed that die fluid is 

 divided into two zones, directly opposite in their powers to 

 the poles of the battery, the virtual change may be regarded 

 as taking |)lace in the two extremities of these zones nearest 

 the neutral point ; so that by a series of decompositions and 

 recomjiositious, the alkaline matters and hydrogen separate at 

 one sidi', and oxygen, pure or in union, at the other. 



2 C 2 In 



