370 



availed myself of the opportunity to ascertain one of the physical 

 properties of this extraordinary metal, which it does not appear 

 has been yet determined, viz. its order in the voltaic series. The 

 following are the results of my experiments. 



Solution of potass acts more energetically and with a greater evo- 

 lution of hydrogen gas upon aluminum than it does on zinc, cadmium 

 or tin. In this liquid aluminum is negative to zinc, and positive to 

 cadmium, tin, lead, iron, copper and platina. Employed as the po- 

 sitive metal, the most steady and energetic current is obtained 

 when it is opposed to copper as the negative metal ; all the other 

 metals negative to it which were tried became rapidly polarized, 

 whether above or below copper in the series. 



In a solution of hydrochloric acid aluminum is negative to zinc 

 and cadmium, and positive to all the other metals above named. 

 With this liquid also copper opposed to it as the negative metal gave 

 the strongest and most constant current. 



Nitric and sulphuric acids are known not to act chemically in any 

 sensible manner on aluminum. With the former acid diluted as 

 the exciting liquid aluminum is negative to zinc, cadmium, tin, lead 

 andiron. The current with zinc is strong; with the other metals 

 very weak, and it is probable that their apparent negative condition 

 is the result of polarization. When aluminum is immersed in dilute 

 sulphuric acid, this metal appears negative to zinc, cadmium, tin 

 and iron, but with lead, on which sulphuric acid has no action, the 

 current is insensible. In both these liquids copper and platina are 

 negative to aluminum, and notwithstanding the apparent absence 

 of chemical action on the latter metal, weak currents are produced. 



It is rather remarkable, that a metal, the atomic number of which 

 is so small, and the specific gravity of which is so low, should occupy 

 such a position in the electromotive scale as to be more negative 

 than zinc in the series. 



VI. ' ' An Experimental Inquiry into the nature of the metamor- 

 phosis of Saccharine Matter, as a normal process of the 

 animal economy." By FREDERICK W. PAVY, M.D. Lond. 

 Communicated by G. O. REES, M.D., F.R.S. 

 This paper was in part read. 



