18J5.] in Oie Physical Sciences. 3 



employing galvanism as an instrument of analysis, and tlie proba- 

 bilitv bv means of it of decomposing many bodies which had pre- 

 viously resisted all the efforts of chemical experiment. 



In this dissertation the author showed that bodies which nave 9 

 chemical affinity for each other are in different states of electricity ; 

 the one being negative, and the other positive. Thus when quick- 

 lime and oxalic acid are brought in contact, and separated, the 

 acid is found to be negative, and the lime positive. Hence the 

 reason why oxygen and acids are attracted by the ikgative pole of 

 the battery. They are charged positively ; and it is a law in elec- 

 tricity that bodies" in different states are attracted by each other. 

 Hydrogen, alkalies, eartlis, and oxides, arc in a positive state of 

 exc-itemeat ; therefore they are attracted to the negative pole of the 

 battery. Sir H. Davy conceives, with Volta, that there is a pecu- 

 liar state of electricity, cither positive or negative, which beiongs 

 to everv body ; that bodies which have an affmity for each other are 

 in different states, and tliat the degree of affinity is proportional to 

 the intensity of tlie^e different states : or, in other words, the more 

 positive one body is, and the more negative another, the greater is 

 the affinity between them. If we bring them into the same state, 

 that is, render ihcni both positive or i)oth negative, they will no 

 longer remain in combinaVion, but will separate from each other. 

 Ileace the reason why common electricity and the galvanic battery 

 decompo.<;es bodies; and it is probable that by its means most bodies 

 may be decomposed, IjecaUse the affinity between all bodies must 

 be deOnite, whereas the galvanic inten>ity may lie increased at 

 pleasure almost to any amount. According to this view of the 

 subject, chemical affinity is the same jiov/er with the attraction 

 which exists between bodies in different states of electrical excite- 

 ment ; and if any means can be fillen upon to measure this power, 

 we shall at the same time have a measure of chemical affinity. 



Such is an outline of the hypothesis of Sir Humphry Davy. 

 Every one, I conceive, who has considered It with atteniiun, must 

 admit the great importance of it as a means of advancing our 

 knowledge of the constituents of bodies, and be aware that it was 

 in consequence of it that Sir H. Davy was led to attempt the de- 

 composition of the alkalies and earti)s, and to obtain the splendid 

 success with which these fortunate attemjjts were attended. He will 

 recollect also the facts advanced in sui)pi>rt of it liv Volta and Mr. 

 IJrande, and the hajjpy facility with vviuLb it enables us to explain 

 many things that formerly appeared exceedingly ol.scure. 



1 am far from j)retrnding to call in question tlie probability that 

 this hypothesis may ultimately turn out accurate, and think it 

 entitled to tlie closest attention of every chemist and electrician ; 

 but if it be correct, I conceive that the tiieory of electricity, which 

 at present prevails, will not be able to stand lis ground. If iingalice 

 and jtositiDe clectrliity be qualities inherent in bodies, and conti- 

 nuing in them after ihcy unite together, 1 cannot lor my part con- 

 ceive the one to con/ibl in a dijicicnaj of electric matter, and the 



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