476 



dilute nitro-sulphuric acid and nitre, produces a more powerful 

 voltaic current than platina does when excited by nitric and 

 sulphuric acid. In consequence of the small quantity of acid 

 contained in the lead cell, its power declined sooner than that 

 of the platina. From the results of several experiments made 

 with the platina and lead batteries, I have come to the con- 

 clusion that the expense of doing a given amount of work by 

 the former, excited by nitric and sulphuric acid, would be 

 about three times as great as if the work were done by the 

 latter, excited by a mixture of nitre and sulphuric acid. 1 have 

 tried a mixture containing one part of sulphuric acid and three 

 parts of water, in which a little sulphate of soda and nitre was 

 dissolved. When the platinized lead was excited by this mix- 

 ture, the power of the battery was very great, but not so great 

 as when the mixture contained as much sulphuric acid as 

 water. I have not as yet tried any other sulphate as a sub- 

 stitute for the sulphuric acid. When the platinized or gilded 

 lead is taken out of the cell, it should be rinsed in water, and 

 dipped into a weak solution of chloride of gold or platina. By 

 this means, and by amalgamating the lead plates with mer- 

 cury, before they are gilded or platinized, the platina or gold 

 powder may be kept on them for a long time. 



" The reason why the platinized or gilded lead produces so 

 powerful a voltaic current is, that the acting metals are not lead 

 and zinc, but platina or gold powder and zinc. It appears to 

 me that the current produced by zinc and platina, or gold 

 powder, is more powerful than that which is produced by zinc 

 and platina, or gold. Perhaps by depositing on lead a powder 

 of some of the metals, such as tungsten, arsenic, &c., which 

 are more negative, compared with zinc, than platina or gold 

 is, a battery may be yet made which will be more powerful 

 than the platina or platinized lead battery. 1 have tried an- 

 timony, but it did not answer." 



