156 MR CONNELL ON THE VOLTAIC DECOMPOSITION OF 



both of solution and of voltaic action, with those in aqueous solutions of the same 

 substances. 



When a saturated solution of well-dried iodide of potassium in alcohol of 0.7918, 

 at 66 F., was thus acted on by 50 pairs of 2-inch plates in the bent tube, p. 153, 

 oxide of zinc, after a short time, separated at both poles, without any appearance 

 of iodine,* and without effervescence at the positive. These appearances can 

 only be explained on the idea of the secondary origin of the iodine, Avhich appears 

 when, instead of zinc, platinum is employed ; and are conformable to the view of 

 the direct decomposition of the water of the absolute alcohol ; and the appearance 

 of oxide of zinc at the negative pole, whether it could only have come by solution 

 and voltaic transference, leads, I conceive, to the view that, even in alcoholic solu- 

 tions of haloid salts, at least those of moderate strength, the salt decomposes the 

 water of the absolute alcohol, and exists in solution as a hydracid salt. But to 

 this latter matter I shall afterwards recur. 



When a solution of chloride of lithium, the salt having been heated until it 

 began to rise in vapour, and then dissolved by heat in alcohol of the above 

 strength, was acted on in the same manner, oxide of zinc separated after a little 

 at the negative pole, with effervescence from that pole, but none from the posi- 

 tive ; and it was somewhat uncertain whether any separation of the oxide took 

 place on the positive side ; but little doubt could exist that the oxide originated, 

 as in the case of iodide of potassium, by the action of the oxygen of water on the 

 zinc, and subsequent solution and transference of the oxide formed. The princi- 

 pal condition of the deposition of oxide of zinc at the positive pole, whether in 

 aqueous or alcoholic solutions, appears to be a pretty rapid formation from brisk 

 action ; and the less powerful the acid, and the less its quantity drawn to the 

 positive side, the more of the oxide separates previous to solution and trans- 

 ference. 



When an alcoholic solution of fused chloride of calcium was employed, there 

 was a slight appearance of deposition on the negative side, but none on the po- 

 sitive, and no effervescence at the latter pole ; the whole action being retarded by 

 the coating of lime which the negative foil soon acquired. With an aqueous so- 

 lution of chloride of calcium, oxide of zinc separated at both poles. 



In regard to alcoholic solutions, therefore, I have seen no reason to depart 

 from the general rule formerly proposed respecting them. 



With respect to pyroxylic solutions, I hav^e made few experiments ; because, 

 if the general rule holds good in regard to alcohol, there can be little doubt that 

 it will embrace pyroxylic spirit, since, as I formerly shewed, the decomposition 

 of its water is much more readily effected than that of alcohol. I found, experi- 



* The zinc pole usually gets slightly blackened both in alcoholic and aqueous solutions, but 

 this darkish matter was carefully examined and found to be merely oxidated zinc. 



