80 The Rev. Dr. Gallants Eoeperiments on the 



of platiiia or cast iron, into a porous cell containing nitrosul- 

 phuric acid. Each of the three acted far more powerfully than 

 the lead plate. The plate coated with the alloy containing the 

 largest proportion of lead acted better than the one whose coat- 

 ing contained least lead, but not so well as the plate on which 

 sulphur was burnt. This last plate produced a galvanic current 

 very nearly equal to that of a platiua or cast-iron plate. I after- 

 wards put into concentrated nitric acid a piece of the tin which 

 was coated mth the alloy of lead and tin, and with sulphur, a 

 piece of one of the alloys of lead and tin and a piece of lead, and 

 left them in the acid for about twenty hours. On taking them 

 out of the acid, I found that a good deal of the lead had been 

 dissolved, but the piece of coated tin and the alloy were merely 

 blackened on the surface. From the results of these experi- 

 ments, it is evident that tin plates, coated with an alloy of lead 

 and tin, in which the proportion of tin is small, are more passive 

 in nitric acid, less oxidable, and consequently better suited for 

 the electrodes of a voltameter than lead plates. The tin plates 

 are stronger and more elastic than leaden ones, and therefore are 

 not so easily brought into contact with each other. It was in 

 last March or April that I discovered that tin plates, coated with 

 an alloy of lead and tin, are less oxidable than lead. Since that 

 time I have in all my experiments used the coated tin plates as 

 electrodes. I have arranged these electrodes in two ways ; in 

 one way for a battery of low intensity, and in another for bat- 

 teries of high intensity, or of a large number of cells all in one 

 series. In one of the former arrangements there were twenty 

 plates, each 13 inches by 4; they were all parallel, and separated 

 from each other by slips of wood about y^gth of an inch thick. 

 Ten of them were connected with one end of the battery ; these 

 were of course the alternate plates ; the other ten were connected 

 with the opposite end. The acting surface of each electrode, 

 including both sides of each plate, was something more than 

 3 square feet. The electrodes for batteries of high intensity 

 are also parallel and separated from each other, about one-six- 

 teenth of an inch, by a non-conductor. But the two outside or 

 terminal plates only are connected with the battery ; one with 

 the negative, the other with the positive end. The terminal 

 plate, which is connected with the top iron plate of the volta- 

 meter, must be covered on the outside by a non-conductor, other- 

 wise the voltaic current would pass to the side of the iron vessel, 

 and would not pass through the plates and fluid interposed be- 

 tween the two outside or terminal plates. The cells between each 

 pair of plates must be made nearly water-tight, and must be open 

 only on the top, in order that when the terminal plates are con- 

 nected with the battery, the voltaic current may have no way of 



