ON THE DECOMPOSITION OF THE EARTHS. 379 



On the first view of the subject, it appeared probabl-^, that It might be sup- 

 llus silex had been formed by the union of the acid and the P^^^^'^^J'^y^*^ 

 alkaline matter in the two cones, and that the experiment composed, *n4 

 demonstrated a decomposition and recomposition of silex; L^ed'^^'^'*"*" 

 but before such a conclusion could be made, many points 

 were to be determined. 



It was possible, that the acid might be nitric acid, produced 

 ^s in other electrical experiments of a similarnature, and that 

 this acid might have dissolved silex, which was precipitated by 

 the alkaline matter at the other pole, which might be either 

 potash used for dissolving the silex, which had adhered to it, 

 notwithstanding the processes of lixiviation in acids, or am* 

 monia produced in consequence of the presence of the at- 

 mosphere; or if potash was present, it was likewise possi- 

 ble, that the silex might have been carried over in solution, 

 with this alkali, from the positive to the negative surface. 



Minute experiments were instituted and completed in the but this not 

 same manner as those detailed in the Philosopliical Transac- * ^ '^^^' 

 fions for 1807, p. 7*, which soon proved, that there was no 

 reason to suppose, that the silex had been changed in these 

 lexperiments. 



The acid proved to be nitric acid, Avhich under the elec-The acid -was 

 trical action seemed to have dissolveil the silex; the alkali"'"''" 

 turned out to be principally fixed alkali; and that it was Alkali not from 

 merely an accidental ingredient, and not a constituent of^^^^ 

 the silex, appeared from this circumstance, that when the 

 same portion of silex was long electrified, by degrees it lost 

 its power of affording the substance in question t. 



This 



* Journal, vol. xviii, p. 325. 



f If silex, tiiat has been carefully washed, after precipitation Common che- 

 hv muriatic acid fioni liqupr silicum, be moistened, and acted on";. "i«'^'o«* 

 py mercui^Y negatively electrified, the mercury soon contams a no- bodies imper- 

 table quantity of potassium. Well washed alurnine, that has been feet, 

 precipitated from alum by carbonate of soda, affords by the saine 

 treatment sodium and potassium, so that the powers of electroche- 

 mical analysis are continually demonstrating the imperfection of the 

 common chemical methods of separating bodies from each other. 

 The purest boracic acid, which can be obtained from borax by 

 chemical decomposition, by electrical analysis is shown to contain 

 ^cth socia, andtlie decomposing acid empjoyed in the process; and 



henge 



