334- Dr. Faradaj^'s Experimental Researches in Electricity, 



Sulphate of zinc with saline "| [" Sulphate of zinc with sulphate of 



water, Ivieldi potash. 



Sulphate of water with sul- y | Sulphate of water with saline 

 phate of potash, J L water. 



In the sulphate of zinc and potash, the whole six atoms of 

 water are retained with considerably greater force than in the 

 sulphate of zinc itself; but even the double salt becomes an- 

 hydrous at 250°, and, indeed, the water retained falls below a 

 single atomic proportion, when the salt is dried in vacuo over 

 sulphuric acid, at a temperature not exceeding 78° Fahren- 

 heit. The sulphate of potash in the double salt has not the 

 effect of neutralizing the acid reaction of sulphate of zinc, ac- 

 cording to my observations ; nor has it that effect in the case 

 of any other double salt. 



I subjoin a table of observations, made on the quantity of 

 water retained by this double salt, in different circumstances. 

 In the first two columns, the composition of the quantities ac- 

 tually examined is stated in grains. 



[To be continued.] 



LVI. Experimental Researches in Electricity. — Eighth Se- 

 ries. By Michael Faraday, D.C.L.F.R.S.Fullerian Prof. 

 Chem, Royal Institution, Corr. Memh. Royal and Imp. Acadd. 

 of Sciences, Paris, Petershurgh, Florence, Copenhagen, Ber- 



tin, 6)C. Sfc. 



[Continued from p. 279.] 



f iii. On associated Voltaic Circles, or the Voltaic Battery. 



989. "PASSING from the consideration of single circles 



-■• (875. &c.) to their association in the voltaic battery, 



it is a very evident consequence, that if matters are so arranged 



