of the Voltaic sustaining Battery, ~39 



deposit led to the consequences already described, but by 

 working through the membrane it destroyed its texture, 

 causing it to leak, and thus rendered the battery unfit for use 

 till a new membrane was supplied, which necessarily caused 

 the entire arrangement to be disturbed. Under these circum- 

 stances I determined to find a substitute, if possible, for the 

 membrane, which should be free from the defects alluded to, 

 and afford me a more perfect and permanent instrument of 

 research. I will not here enter into a detail of the various 

 substances experimented upon ; suffice it to say, that I used 

 different sorts of wood, parchment, different sorts of paper, 

 unglazed earthenware as recommended by Daniell, &c. but 

 without being satisfied with the results. However, in conse- 

 quence of some remarks made upon the action of the battery 

 when I employed the wooden partitions, I resolved to give 

 them a second trial ; but upon this occasion I perceived the 

 expediency of purifying the wood before it was used, and ac- 

 cordingly after the partition had been constructed, I im- 

 mersed it in boiling v/ater containing a small proportion of 

 sulphuric acid, and kept it therein for about an hour; it was 

 then placed for some time in cold water, and on trying it sub- 

 sequently in the battery, I found that in the first instance it 

 answered expectation so far as affording a free passage to the 

 electric current ; and after a lengthened trial my anticipations 

 were fully realized by the fact, of all metallic deposit upon the 

 ititerposed substance being prevented, 



I thus obtained a substance which as a medium of conduc- 

 tion answered all the purposes of membrane or other sub- 

 stances, while it possessed the important advantages of at- 

 tracting no metallic particles, of non-liability to fracture or 

 other injuries, of being always fit for use*, no matter how 

 long it may have been previously employed, and last, not 

 least, of being infinitely cheaper than membrane or earthen- 

 ware. I have been using batteries with these partitions for 

 nearly two years, and have every reason to feel satisfied with 

 their action. I will now describe the voltaic arrangements 

 which I at present use, and wish previously to remark, that 

 continued investigation supports my estimation of closed cop- 

 per cylinders in preference to my original employment of 

 open ones. 



In the first form, I use a thin copper cylinder about six 

 inches in height and three in diameter ; the bottom and other 



* It may be well to state, that previously to employing the wooden 

 cylinders, it is necessary to make them thoroughly moist by placing them 

 for a couple of hours in a vessel of water, with which a very small quantity 

 of sulphuric acid or of common salt has been mixed. 



