Mr. Mullins on the Construction of Voltaic Batteries. 283 



valleys which stretch between the Kyarcla-dun and the valley of Pinjor, in 

 the Sivalik or sub-Hintalayan belt of hills, associated with bones of the 

 fossil Elephant, Mastodon, Rhinoceros, Hippopotamus, &c. So far as our 

 researches yet go, the Sivatlierium was not numerous. Compared with the 

 Mastodon and Hippopotamus {H. Sivalensis, Nobis, a new species charac- 

 terized by having six incisors in either jaw, ) it was very rare. 

 Nort/ieni Dodb, Sejjl. 15, 1835. 



LVIII. Observations on the Construction of Voltaic Batteries ; 

 •with a Description of a Battery exhibited at the Uoijal In- 

 stitution of Great Britain, June 3, 1 836, in "which an uniform 

 and po-wcrful current is sustained for amj period required. 

 By Fred. Wm. Mullins, E'.q., M.P., F.S.S., S>-c.* 



IIJ AVING for some years devoted all the time I could spare 

 -*- -*• from other avocations to researches in voltaism and elec- 

 tro-magnetism, I frequently experienced considerable incon- 

 venience from the impossibility of keeping up an equally pow- 

 erful current of electricity for a period sufficiently long to 

 answer my purposes ; and in one particular instance, which I 

 shall more especially refer to in a future paper, as con- 

 nected with a very important discovery, the obstruction to 

 the inquiries 1 was then making was so great, that I resolved, 

 if possible, to conquer the difficulty, and conceived that not- 

 withstanding the disappointments that had previously attended 

 similar attempts, some means might still be discovered by 

 which those consequences of chemical action on the metals 

 employed in the galvanic circuit, and which Sir Humphry 

 Davy and other distinguished philosophers had decided to be 

 the chief cause of the decline of electric power, might be pre- 

 vented, or, at all events, considerably diminished. I therefore 

 commenced a series of experiments on this subject, in the 

 course of which it struck me that a conducting substance in- 

 terposed between the two metals would effectually protect 

 both metals from the injurious effisct of the gases and oxides 

 formed while the battery was in action, while the electric cur- 

 rent would find a free passage, and a surface of copper, or 

 whatever other metal performed its functions, in the fittest 

 state to receive it from the electrolyte. I hatl been previously 

 in the habit of using membranous substances as conductors 

 of voltaic electricity, in a course of experiments in which 

 I had been engaged with the view of obtaining a new mode 

 of developing voltaic power ; and having found that thin 

 membranes, when moistened in alkaline or acid solutions, af- 



• ConuDiniicated by the Author. An abstract of Professor DaniclTs 

 paper on the Constant Voltaic Battery, recently constructed by him, will be 



found in our last volume, p. 421. 



2 K2 



