72 Mr Kemp oti a New Kind of' Galvanic Pile. 



eighth of an inch ; the whole is then rendered water-tight by a coating of wax, 

 care being taken to keep the projecting point of the wire quite free from wax. 



A quantity of mercury, merely sufficient to cover the bottom, is poured 

 into the cup, which is in contact with the zinc plate EF, through the me- 

 dium of the wire- Over this is poured as much diluted muriatic acid as will 

 nearly fill the cup. In this manner we have obtained one complete plate, 

 consisting of zinc, mercury and acid ; and, by a continuation of the series, they 

 may be increased to any extent. 



In erecting this pile, after the mercury and acid have been poured into the 

 cups as stated, they are to be placed above each other, as appears in Fig. 4. 

 Plate II. ; the zinc plate of the one will then be in contact with the acid 

 contained in that immediately under it ; the cup itself resting on a small 

 check cut round the lower part of the rim. In this manner, any number of 

 plates may be arranged, and, if requisite, kept in their proper places by means 

 of glass-rods inserted into the base. This, however, is only necessary when 

 the pile is of small diameter ; for, in one of a larger diameter, a sufficient 

 number may be raised, or they can be arranged in two or more columns, and 

 connected as in the common pile. 



For the purpose of experimenting with this apparatus, a small brass socket 

 G passes into the base, and communicates with the mercury in the under- 

 most cup ; into this socket a hole is drilled for inserting the wire. Another 

 is attached to the capital or uppermost plate of the pile, from which a wire 

 can be brought to complete the circuit, and varied according as the experi- 

 ment requires. 



The zinc plate is made convex, in order to allow the hydrogen formed at 

 its under surface to escape, which would otherwise collect into a globule, and 

 displace the acid ; the use of the projecting edge on the cups is to prevent 

 the running over, and forming a communication between the different parts 

 of the pile, and destrojdng its action. 



In this arrangement, as the zinc is the metal acted upon by the acid, it 

 very soon becomes corroded, and, in this respect, is liable to the same objections 

 as the ordinary galvanic apparatus. 



And in a battery where the negative metal is liquid, and the positive so- 

 lid, no increase of power is obtained over the ordinary apparatus, — a circum- 

 stance which would seem to indicate that the negative liquid metal acts mere- 

 ly the part of a conductor ; nor can it, while the positive remains solid, trans- 

 mit the full effect of larger batteries, but must necessarily reduce it in the 

 same proportion as a solid pile ; the effect, however, would be very different, 

 were the positive plate liquid, and the negative solid. This I have endea- 

 voured to accomplish by the following arrangement, in which the positive 

 plate is an amalgam of mercury and zinc. 



The form of it is the same as that of the pile already described, with this 

 material difference, that, instead of pure mercury, copper is used as the ne- 

 gative plate, and instead of zinc, an amalgam of zinc and mercury as the po- 

 sitive one ; and whether we take into consideration the new field it opens up 

 for tracing the laws which govern galvanic action, — its powerful effects on 

 the magnet, and in the combustion of the metals,— or the rapidity with which 



